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Preview: Journal of Antimicrobial Chemotherapy - recent issues

Journal of Antimicrobial Chemotherapy - recent issues



Journal of Antimicrobial Chemotherapy - RSS feed of recent issues (covers the latest 3 issues, including the current issue)



 



Role of cephalosporins in the era of Clostridium difficile infection

2016-12-16T07:03:21-08:00

The incidence of Clostridium difficile infection (CDI) in Europe has increased markedly since 2000. Previous meta-analyses have suggested a strong association between cephalosporin use and CDI, and many national programmes on CDI control have focused on reducing cephalosporin usage. Despite reductions in cephalosporin use, however, rates of CDI have continued to rise. This review examines the potential association of CDI with cephalosporins, and considers other factors that influence CDI risk. EUCLID (the EUropean, multicentre, prospective biannual point prevalence study of CLostridium difficile Infection in hospitalized patients with Diarrhoea) reported an increase in the annual incidence of CDI from 6.6 to 7.3 cases per 10 000 patient bed-days from 2011–12 to 2012–13, respectively. While CDI incidence and cephalosporin usage varied widely across countries studied, there was no clear association between overall cephalosporin prescribing (or the use of any particular cephalosporin) and CDI incidence. Moreover, variations in the pharmacokinetic and pharmacodynamic properties of cephalosporins of the same generation make categorization by generation insufficient for predicting impact on gut microbiota. A multitude of additional factors can affect the risk of CDI. Antibiotic choice is an important consideration; however, CDI risk is associated with a range of antibiotic classes. Prescription of multiple antibiotics and a long duration of treatment are key risk factors for CDI, and risk also differs across patient populations. We propose that all of these are factors that should be taken into account when selecting an antibiotic, rather than focusing on the exclusion of individual drug classes.




Less-drug regimen including atazanavir in maintenance treatment of HIV infection: how, who, when, why?

2016-12-16T07:03:21-08:00

For many patients living with HIV-1, the efficacy of combined ART (cART) has made the infection turn to a chronic disease. Because cART is associated with a risk of long-term toxicity, switching patients with virological success to another therapy remains a major issue. Studies undertaken and published over recent years have shown that switching patients exhibiting virological suppression to less-drug regimens (LDR) is a possible option of maintenance strategy. The use of ritonavir-boosted PIs (PI/r) as the backbone of LDR-based maintenance therapy is consistent with their virological potency and a high genetic barrier of resistance. Atazanavir is the most documented PI/r regarding maintenance in dual therapy, with favourable results in terms of virological suppression, tolerance improvement and absence of emergence of mutations. Furthermore, atazanavir is the only commonly prescribed PI that can be used after withdrawal of ritonavir, with maintenance of virological suppression whatever the backbone of associated NRTIs. Based on clinical studies, and taking into account the characteristics of the patients included, one may consider that for any patient with a virological suppression on cART for at least 12 months, with the nadir CD4 >100 cells/mm3 and an absence of encephalitis, an LDR-based maintenance therapy including atazanavir can be considered. Cumulative genotypes must be available to make sure that the LDR will not jeopardize future therapeutic options. The final decision regarding the most appropriate LDR must be guided by the objectives shared by the physician and his/her patient.




Polymyxin monotherapy or in combination against carbapenem-resistant bacteria: systematic review and meta-analysis

2016-12-16T07:03:21-08:00

Objectives

The objective of this study was to summarize available data on polymyxin-based combination therapy or monotherapy for carbapenem-resistant Gram-negative bacteria.

Methods

This is a systematic review. We included observational studies and randomized controlled trials (RCTs) comparing polymyxin monotherapy versus polymyxin-based combination therapy in adult patients with infections caused by carbapenem-resistant or carbapenemase-producing Gram-negative bacteria. Only named antibiotic regimens were included. The primary outcome was 30 day mortality. Unadjusted OR (uOR) and adjusted OR where available with 95% CI were pooled in random-effects meta-analyses.

Results

Twenty-two studies including 28 comparisons were included. Polymyxin monotherapy was associated with a uOR of 1.58 (95% CI = 1.03–2.42) for mortality compared with polymyxin/carbapenem combination therapy (seven observational studies, 537 patients), without heterogeneity. Subgrouping studies to serious and critical risk of bias resulted in uORs of 0.94 (95% CI = 0.42–2.09) and 1.94 (95% CI = 1.17–3.23), respectively. Mortality was significantly higher with polymyxin monotherapy compared with combination therapy with tigecycline, aminoglycosides or fosfomycin (potentially double-coverage regimens): uOR of 1.57 (95% CI = 1.06–2.32) overall (10 observational studies and 1 RCT, 585 patients, no heterogeneity) and uOR of 2.09 (95% CI = 1.21–3.6) for Klebsiella pneumoniae bacteraemia (7 observational studies, 285 patients, no heterogeneity); very low quality evidence. Two RCTs and one observational study assessing rifampicin/colistin combination therapy for Acinetobacter baumannii infections showed no difference in mortality compared with colistin monotherapy; moderate quality evidence.

Conclusions

The significant association observed in observational studies between polymyxin monotherapy and mortality cannot be taken as proof of combination therapy effects due to the low quality of the evidence. The only three RCTs to date show no effect of rifampicin/colistin or fosfomycin/colistin on mortality for Acinetobacter infections.




Genomic analysis of 495 vancomycin-resistant Enterococcus faecium reveals broad dissemination of a vanA plasmid in more than 19 clones from Copenhagen, Denmark

2016-12-16T07:03:21-08:00

Objectives

From 2012 to 2014, there has been a huge increase in vancomycin-resistant (vanA) Enterococcus faecium (VREfm) in Copenhagen, Denmark, with 602 patients infected or colonized with VREfm in 2014 compared with just 22 in 2012. The objective of this study was to describe the genetic epidemiology of VREfm to assess the contribution of clonal spread and horizontal transfer of the vanA transposon (Tn1546) and plasmid in the dissemination of VREfm in hospitals.

Methods

VREfm from Copenhagen, Denmark (2012–14) were whole-genome sequenced. The clonal structure was determined and the structure of Tn1546-like transposons was characterized. One VREfm isolate belonging to the largest clonal group was sequenced using long-read technology to close a 37 kb vanA plasmid.

Results

Phylogeny revealed a polyclonal structure where 495 VREfm isolates were divided into 13 main groups and 7 small groups. The majority of the isolates were located in three groups (n = 44, 100 and 218) and clonal spread of VREfm between wards and hospitals was identified. Five Tn1546-like transposon types were identified. A dominant truncated transposon (type 4, 92%) was spread across all but one VREfm group. The closed vanA plasmid was highly covered by reads from isolates containing the type 4 transposon.

Conclusions

This study suggests that it was the dissemination of the type 4 Tn1546-like transposon and plasmid via horizontal transfer to multiple populations of E. faecium, followed by clonal spread of new VREfm clones, that contributed to the increase in and diversity of VREfm in Danish hospitals.




Long-term clonal dynamics of Enterococcus faecium strains causing bloodstream infections (1995-2015) in Spain

2016-12-16T07:03:21-08:00

Objectives

To investigate the population structure of Enterococcus faecium causing bloodstream infections (BSIs) in a tertiary Spanish hospital with low glycopeptide resistance, and to enhance our knowledge of the dynamics of emergence and spread of high-risk clonal complexes.

Methods

All available E. faecium causing BSIs (n = 413) in our hospital (January 1995–May 2015) were analysed for antibiotic susceptibility (CLSI), putative virulence traits (PCR, esp, hylEfm) and clonal relationship (SmaI-PFGE, MLST evaluated by goeBURST and BAPS).

Results

The increased incidence of BSIs caused by enterococci [2.3 of attended patients (inpatients and outpatients) in 1996 to 3.0 in 2014] significantly correlated with the increase in BSIs caused by E. faecium (0.33 of attended patients in 1996 to 1.3 in 2014). The BSIs Enterococcus faecalis:E. faecium ratio changed from 5:1 in 1996 to 1:1 in 2014. During the last decade an increase in E. faecium BSIs episodes in cancer patients (10.9% in 1995–2005 and 37.1% in 2006–15) was detected. Ampicillin-susceptible E. faecium (ASEfm; different STs/BAPS) and ampicillin-resistant E. faecium (AREfm; ST18/ST17-BAPS 3.3a) isolates were recovered throughout the study. Successive waves of BAPS 2.1a-AREfm (ST117, ST203 and ST80) partially replaced ASEfm and ST18-AREfm since 2006.

Conclusions

Different AREfm clones (belonging to BAPS 2.1a and BAPS 3.3a) consistently isolated during the last decade from BSIs might be explained by a continuous and dense colonization (favouring both invasion and cross-transmission) of hospitalized patients. High-density colonization by these clones is probably enhanced in elderly patients by heavy and prolonged antibiotic exposure, particularly in oncological patients.




In vitro activity of ceftaroline against clinical Staphylococcus aureus isolates collected during a national survey conducted in Belgian hospitals

2016-12-16T07:03:21-08:00

Objectives

The aim of this study was to estimate the in vitro activity of ceftaroline against clinical Staphylococcus aureus isolates collected during national surveillance in Belgian acute-care hospitals. Ceftaroline-resistant isolates were further investigated for their resistance mechanisms.

Methods

From October 2013 to March 2014, 155 laboratories of Belgian acute-care hospitals were invited to send to the National Reference Centre—Staphylococcus aureus (Belgium) up to five non-duplicate S. aureus including three MRSA and two MSSA from hospitalized patients. Isolates were analysed by spa typing, SCCmec typing (for MRSA) and PCR for detection of 16S-mecA-nuc and 16S-mecC. MICs of oxacillin, cefoxitin and ceftaroline were determined by the broth microdilution method. The nucleotide sequences of mecA, native pbp and gdpP genes of isolates with reduced susceptibility to ceftaroline were analysed for the presence of mutations responsible for amino acid substitutions.

Results

Ninety-nine percent of isolates, including MRSA (n = 284) and MSSA (n = 131), were susceptible to ceftaroline. Only four MRSA isolates showed resistance to ceftaroline (MIC = 2 mg/L). These four isolates belonged to lineages CC5 (n = 1), CC22 (n = 2) and CC8 (n = 1). Two isolates (CC22 and CC8) carried mutations in mecA, as well as in other pbp genes. The remaining isolates carried mutations in native pbp genes or in gdpP.

Conclusions

This is the first Belgian in vitro survey on ceftaroline activity against S. aureus. This antibiotic showed excellent activity against MRSA and MSSA, and only a few MRSA isolates with resistance were found. Reduced susceptibility to ceftaroline seems a complex phenomenon due to the accumulation of mutations in genes involved in β-lactam tolerance.




Report of mecC-carrying MRSA in domestic swine

2016-12-16T07:03:21-08:00

Objectives

We unexpectedly identified MRSA isolates carrying mecC (mecC-MRSA) from a Danish swine farm located in eastern Zealand. The objective of the present study was to investigate the origin of these isolates and their genetic relatedness to other mecC-MRSA isolates from Zealand.

Methods

WGS was used to infer the phylogenetic relationship between 19 identified mecC-MRSA isolates from the swine farm and 34 additional epidemiologically unrelated human isolates from the same geographical region of Denmark. Variations in the accessory genome were investigated by bioinformatics tools, and antibiotic susceptibility profiles were assessed by MIC determination.

Results

mecC-MRSA was isolated from a domestic swine farm, but not from cattle reared at the same farm. Phylogenetic analysis revealed that all mecC-MRSA isolates from both farm animals and workers formed a separate cluster, whereas human isolates from the same municipality belonged to a closely related cluster. Analysis of the accessory genome supported this relationship.

Conclusions

To the best of our knowledge, this is the first report of mecC-MRSA isolated from domestic swine. The investigation strongly indicates that transmission of mecC-MRSA has taken place on the swine farm between the farmers and swine. The close clustering of farm isolates and isolates from the same municipality suggests a local transmission of mecC-MRSA.




A new mosaic integrative and conjugative element from Streptococcus agalactiae carrying resistance genes for chloramphenicol (catQ) and macrolides [mef(I) and erm(TR)]

2016-12-16T07:03:21-08:00

Objectives

To investigate the genetic basis of catQ-mediated chloramphenicol resistance in Streptococcus agalactiae.

Methods

Two clinical strains of catQ-positive chloramphenicol-resistant S. agalactiae (Sag236 and Sag403) were recently isolated, typed (MLST, PFGE pulsotypes, capsular types) and their antibiotic resistances investigated by phenotypic and genotypic approaches. Several molecular methods (PCR mapping, restriction assays, Southern blotting, sequencing and sequence analysis, conjugal transfer assays) were used to determine the genetic context of catQ and characterize a genetic element detected in the isolates.

Results

Sag236 and Sag403 shared the same ST (ST19), but exhibited a different capsular type (III and V, respectively) and pulsotype. Both harboured the macrolide resistance genes mef(I) and erm(TR) and the tetracycline resistance gene tet(M). Accordingly, they were resistant to chloramphenicol, erythromycin and tetracycline. catQ and mef(I) were associated in an IQ module that was indistinguishable in Sag236 and Sag403. In mating assays, chloramphenicol and erythromycin resistance proved transferable, at low frequency, only from Sag236. Transconjugants carried not only catQ and mef(I), but also erm(TR), suggesting a linkage of the three resistance genes in a mobile element, which, though seemingly non-mobile, was also detected in Sag403. The new element (designated ICESag236, ~110 kb) results from recombination of two integrative and conjugative elements (ICEs) originally described in different streptococcal species: S. agalactiae ICESagTR7, carrying erm(TR); and Streptococcus pneumoniae ICESpn529IQ, carrying the prototype IQ module.

Conclusions

These findings strengthen the notion that widespread streptococcal ICEs may form mosaics that enhance their diversity and spread, broaden their host range and carry new cargo genes.




Fosfomycin resistance in Acinetobacter baumannii is mediated by efflux through a major facilitator superfamily (MFS) transporter--AbaF

2016-12-16T07:03:21-08:00

Objectives

To decipher the function of A1S_1331, named AbaF (Acinetobacter baumannii Fosfomycin efflux), one of the primary targets of AbsR25, a small RNA of A. baumannii.

Methods

abaF was cloned in a multicopy plasmid and expressed from its native promoter in an efflux-deficient strain—Escherichia coli KAM32. Drug susceptibility, accumulation and efflux of ethidium bromide (EtBr) were determined in this strain. abaF was disrupted in A. baumannii using homologous recombination and its effect on drug susceptibility, biofilm formation and virulence was studied. Expression of abaF was followed by quantitative PCR in fosfomycin-challenged A. baumannii and fosfomycin-resistant mutants of A. baumannii. Expression of abaF in clinical strains of A. baumannii was determined by RT-PCR.

Results

Expression of abaF in E. coli KAM32 resulted in increased resistance to fosfomycin. Lower accumulation and higher efflux of EtBr from this strain confirmed the role of AbaF as an efflux pump. Disruption of abaF in A. baumannii caused an increase in fosfomycin susceptibility and a decrease in biofilm formation and virulence. The expression of abaF was higher in A. baumannii cells exposed to fosfomycin and in cells resistant to higher concentrations of fosfomycin. The clinically relevant strains of A. baumannii also tested positive for the expression of abaF.

Conclusions

The results of this study suggest that efflux is an important mechanism of fosfomycin resistance and AbaF is involved in fosfomycin resistance in A. baumannii. AbaF also seems to play a role in biofilm formation and virulence of A. baumannii.




Ciprofloxacin selects for RNA polymerase mutations with pleiotropic antibiotic resistance effects

2016-12-16T07:03:21-08:00

Objectives

Resistance to the fluoroquinolone drug ciprofloxacin is commonly linked to mutations that alter the drug target or increase drug efflux via the major AcrAB-TolC transporter. Very little is known about other mutations that might also reduce susceptibility to ciprofloxacin. We discovered that an Escherichia coli strain experimentally evolved for resistance to ciprofloxacin had acquired a mutation in rpoB, the gene coding for the β-subunit of RNA polymerase. The aim of this work was to determine whether this mutation, and other mutations in rpoB, contribute to ciprofloxacin resistance and, if so, by which mechanism.

Methods

Independent lineages of E. coli were evolved in the presence of ciprofloxacin and clones from endpoint cultures were screened for mutations in rpoB. Ciprofloxacin-selected rpoB mutations were identified and characterized in terms of effects on susceptibility and mode of action.

Results

Mutations in rpoB were selected at a high frequency in 3 out of 10 evolved lineages, in each case arising after the occurrence of mutations affecting topoisomerases and drug efflux. All ciprofloxacin-selected rpoB mutations had a high fitness cost in the absence of drug, but conferred a competitive advantage in the presence of ciprofloxacin. RNA sequencing and quantitative RT–PCR analysis showed that expression of mdtK, encoding a multidrug efflux transporter, was significantly increased by the ciprofloxacin-selected rpoB mutations. The susceptibility phenotype was shown to depend on the presence of an active mdtK and a mutant rpoB allele.

Conclusions

These data identify mutations in RNA polymerase as novel contributors to the evolution of resistance to ciprofloxacin and show that the phenotype is mediated by increased MdtK-dependent drug efflux.




Low biological cost of carbapenemase-encoding plasmids following transfer from Klebsiella pneumoniae to Escherichia coli

2016-12-16T07:03:21-08:00

Objectives

The objective of this study was to determine the biological cost, stability and sequence of two carbapenemase-encoding plasmids containing blaKPC-2 (pG12-KPC-2) and blaVIM-1 (pG06-VIM-1) isolated from Klebsiella pneumoniae when newly acquired by uropathogenic Escherichia coli clinical isolates of different genetic backgrounds.

Methods

The two plasmids were transferred into plasmid-free E. coli clinical isolates by transformation. The fitness effect of newly acquired plasmids on the host cell was assessed in head-to-head competitions with the corresponding isogenic strain. Plasmid stability was estimated by propagating monocultures for ~312 generations. Plasmid nucleotide sequences were determined using next-generation sequencing technology. Assembly, gap closure, annotation and comparative analyses were performed.

Results

Both plasmids were stably maintained in three of four E. coli backgrounds and resulted in low to moderate reductions in host fitness ranging from 1.1% to 3.6%. A difference in fitness cost was observed for pG12-KPC-2 between two different genetic backgrounds, while no difference was detected for pG06-VIM-1 between three different genetic backgrounds. In addition, a difference was observed between pG12-KPC-2 and pG06-VIM-1 in the same genetic background. In general, the magnitude of biological cost of plasmid carriage was both host and plasmid dependent. The sequences of the two plasmids showed high backbone similarity to previously circulating plasmids in K. pneumoniae.

Conclusions

The low to modest fitness cost of newly acquired and stably maintained carbapenemase-encoding plasmids in E. coli indicates a potential for establishment and further dissemination into other Enterobacteriaceae species. We also show that the fitness cost is both plasmid and host specific.




Occurrence and characterization of blaNDM-5-positive Klebsiella pneumoniae isolates from dairy cows in Jiangsu, China

2016-12-16T07:03:21-08:00

Objectives

To investigate the epidemiological characteristics and the surrounding genetic structure of the blaNDM-5 gene in Klebsiella pneumoniae derived from dairy cows in Jiangsu Province, China.

Methods

Ten carbapenem-resistant K. pneumoniae were collected from three dairy farms and were screened for the presence of carbapenemase genes using PCR and sequencing. PFGE and MLST were conducted to analyse the genetic relatedness of the blaNDM-5-harbouring K. pneumoniae isolates. The location of blaNDM-5 was identified by S1 nuclease-PFGE and Southern blotting. The transferability and profiles of blaNDM-5-carrying plasmids were analysed by conjugation experiments, and PCR-based replicon typing and RFLP, respectively. The surrounding genetic structure of the blaNDM-5 gene was obtained using WGS and PCR mapping.

Results

All 10 K. pneumoniae from dairy cows harboured the blaNDM-5 gene, exhibited resistance to multiple antimicrobials and belonged to five STs, of which ST1661 and ST2108 were the most prevalent. The blaNDM-5 gene was located on the ~46 kb IncX3 plasmid in all isolates and these plasmids could be conjugated to an Escherichia coli recipient with no additional resistance profiles transferred. All blaNDM-5-carrying plasmids shared similar genetic contexts and were nearly identical to that of the human K. pneumoniae plasmid (pNDM-MGR194) previously reported in India.

Conclusions

This was the first case of blaNDM-5-positive K. pneumoniae identified from dairy cows in China. The IncX3 pNDM-MGR194-like plasmid disseminated among cow farms should be highlighted and its potential role in mediating transmission of the blaNDM gene between bacteria from humans and animals requires further monitoring.




Emergence of meningococci with reduced susceptibility to third-generation cephalosporins

2016-12-16T07:03:21-08:00

Objectives

Reduced susceptibility to penicillin G in Neisseria meningitidis is mainly due to alterations in PBP2 encoded by the penA gene. However, this phenotype was not associated with reduced susceptibility to third-generation cephalosporins (C3Gs). We aimed to study the emergence of meningococci with reduced susceptibility to C3Gs (MIC >0.06 mg/L) in France since 2012.

Methods

Invasive meningococcal isolates were typed by MLST and penA sequencing and their antibiotic susceptibility was tested.

Results

Isolates with reduced susceptibility to C3Gs represented 2% of all invasive isolates from 2012–15, but were absent before. They harboured a new penA allele, penA327, that was also detected in isolates from urethritis cases and in gonococci.

Conclusions

Surveillance of these isolates should be enhanced as they may jeopardize the use of C3Gs in the management of invasive meningococcal disease.




IncN ST7 epidemic plasmid carrying blaIMP-4 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China

2016-12-16T07:03:21-08:00

Objectives

To characterize blaIMP-4-carrying plasmids originating from inpatients in Hong Kong.

Methods

Sixteen blaIMP-4-carrying plasmids identified among Enterobacteriaceae (nine Escherichia coli, four Klebsiella pneumoniae, two Citrobacter freundii and one Enterobacter cloacae) recovered from 15 patients were characterized. The isolates, collected during January 2010 to December 2013, were retrospectively investigated by plasmid sequencing, molecular and fitness studies.

Results

The blaIMP-4-carrying plasmids belonged to the IncN ST7 lineage (~50 kb). Twelve of the 16 plasmids were epidemiologically linked to seven different regions in China. Alignment of the complete plasmid sequences showed identical plasmid backbones and two highly similar resistance regions, each carrying one of two resistance genes (blaIMP-4 and qnrS1). The blaIMP-4 was detected in a class 1 integron (containing blaIMP-4 and intron Kl.pn.13) that is part of an IS6100-IS26 transposon-like structure. The nine E. coli carrying the epidemic plasmid belonged to multiple multilocus STs (six ST542, one ST131, one ST657 and one ST3177). Fitness assays performed on E. coli J53 recipients showed that the presence of the epidemic plasmid did not have a significant biological cost.

Conclusions

This study identified a blaIMP-4-carrying IncN ST7 plasmid disseminated among multiple enterobacterial species originating from patients with epidemiological links to different regions in China.




Identification of bacterial pathogens and antimicrobial resistance directly from clinical urines by nanopore-based metagenomic sequencing

2016-12-16T07:03:21-08:00

Objectives

The introduction of metagenomic sequencing to diagnostic microbiology has been hampered by slowness, cost and complexity. We explored whether MinION nanopore sequencing could accelerate diagnosis and resistance profiling, using complicated urinary tract infections as an exemplar.

Methods

Bacterial DNA was enriched from clinical urines (n = 10) and from healthy urines ‘spiked’ with multiresistant Escherichia coli (n = 5), then sequenced by MinION. Sequences were analysed using external databases and bioinformatic pipelines or, ultimately, using integrated real-time analysis applications. Results were compared with Illumina data and resistance phenotypes.

Results

MinION correctly identified pathogens without culture and, among 55 acquired resistance genes detected in the cultivated bacteria by Illumina sequencing, 51 were found by MinION sequencing directly from the urines; with three of the four failures in an early run with low genome coverage. Resistance-conferring mutations and allelic variants were not reliably identified.

Conclusions

MinION sequencing comprehensively identified pathogens and acquired resistance genes from urine in a timeframe similar to PCR (4 h from sample to result). Bioinformatic pipeline optimization is needed to better detect resistances conferred by point mutations. Metagenomic-sequencing-based diagnosis will enable clinicians to adjust antimicrobial therapy before the second dose of a typical (i.e. every 8 h) antibiotic.




Antimicrobial peptide exposure selects for Staphylococcus aureus resistance to human defence peptides

2016-12-16T07:03:21-08:00

Background

The clinical development of antimicrobial peptides (AMPs) is currently under evaluation to combat the rapid increase in MDR bacterial pathogens. However, many AMPs closely resemble components of the human innate immune system and the ramifications of prolonged bacterial exposure to AMPs are not fully understood.

Objectives

We show that in vitro serial passage of a clinical USA300 MRSA strain in a host-mimicking environment containing host-derived AMPs results in the selection of stable AMP resistance.

Methods

Serial passage experiments were conducted using steadily increasing concentrations of LL-37, PR-39 or wheat germ histones. WGS and proteomic analysis by MS were used to identify the molecular mechanism associated with increased tolerance of AMPs. AMP-resistant mutants were characterized by measuring in vitro fitness, AMP and antibiotic susceptibility, and virulence in a mouse model of sepsis.

Results

AMP-resistant Staphylococcus aureus mutants often displayed little to no fitness cost and caused invasive disease in mice. Further, this phenotype coincided with diminished susceptibility to both clinically prescribed antibiotics and human defence peptides.

Conclusions

These findings suggest that therapeutic use of AMPs could select for virulent mutants with cross-resistance to human innate immunity as well as antibiotic therapy. Thus, therapeutic use of AMPs and the implications of cross-resistance need to be carefully monitored and evaluated.




Short- and long-term effects of oral vancomycin on the human intestinal microbiota

2016-12-16T07:03:21-08:00

Background

Oral vancomycin remains the mainstay of therapy for severe infections produced by Clostridium difficile, the most prevalent cause of healthcare-associated infectious diarrhoea in developed countries. However, its short- and long-term effects on the human intestinal microbiota remain largely unknown.

Methods

We utilized high-throughput sequencing to analyse the effects of vancomycin on the faecal human microbiota up to 22 weeks post-antibiotic cessation. The clinical relevance of the observed microbiota perturbations was studied in mice.

Results

During vancomycin therapy, most intestinal microbiota genera and operational taxonomic units (OTUs) were depleted in all analysed subjects, including all baseline OTUs from the phylum Bacteroidetes. This was accompanied by a vast expansion of genera associated with infections, including Klebsiella and Escherichia/Shigella. Following antibiotic cessation, marked differences in microbiota resilience were observed among subjects. While some individuals recovered a microbiota close to baseline composition, in others, up to 89% of abundant OTUs could no longer be detected. The clinical relevance of the observed microbiota changes was further demonstrated in mice, which developed analogous microbiota alterations. During vancomycin treatment, mice were highly susceptible to intestinal colonization by an antibiotic-resistant pathogen and, upon antibiotic cessation, a less-resilient microbiota allowed higher levels of pathogen colonization.

Conclusions

Oral vancomycin induces drastic and consistent changes in the human intestinal microbiota. Upon vancomycin cessation, the microbiota recovery rate varied considerably among subjects, which could influence, as validated in mice, the level of susceptibility to pathogen intestinal colonization. Our results demonstrate the negative long-term effects of vancomycin, which should be considered as a fundamental aspect of the cost–benefit equation for antibiotic prescription.




Antimicrobial activity of antisense peptide-peptide nucleic acid conjugates against non-typeable Haemophilus influenzae in planktonic and biofilm forms

2016-12-16T07:03:21-08:00

Background

Antisense peptide nucleic acids (PNAs) are synthetic polymers that mimic DNA/RNA and inhibit bacterial gene expression in a sequence-specific manner.

Methods

To assess activity against non-typeable Haemophilus influenzae (NTHi), we designed six PNA-peptides that target acpP, encoding an acyl carrier protein. MICs and minimum biofilm eradication concentrations (MBECs) were determined. Resistant strains were selected by serial passages on media with a sub-MIC concentration of acpP-PNA.

Results

The MICs of six acpP-PNA-peptides were 2.9–11 mg/L (0.63–2.5 μmol/L) for 20 clinical isolates, indicating susceptibility of planktonic NTHi. By contrast, MBECs were up to 179 mg/L (40 μmol/L). Compared with one original PNA-peptide (acpP-PNA1-3'N), an optimized PNA-peptide (acpP-PNA14-5'L) differs in PNA sequence and has a 5' membrane-penetrating peptide with a linker between the PNA and peptide. The optimized PNA-peptide had an MBEC ranging from 11 to 23 mg/L (2.5–5 μmol/L), indicating susceptibility. A resistant strain that was selected by the original acpP-PNA1-3'N had an SNP that introduced a stop codon in NTHI0044, which is predicted to encode an ATP-binding protein of a conserved ABC transporter. Deletion of NTHI0044 caused resistance to the original acpP-PNA1-3'N, but showed no effect on susceptibility to the optimized acpP-PNA14-5'L. The WT strain remained susceptible to the optimized PNA-peptide after 30 serial passages on media containing the optimized PNA-peptide.

Conclusions

A PNA-peptide that targets acpP, has a 5' membrane-penetrating peptide and has a linker shows excellent activity against planktonic and biofilm NTHi and is associated with a low risk for induction of resistance.




Antimicrobial resistance in Shiga toxin-producing Escherichia coli serogroups O157 and O26 isolated from human cases of diarrhoeal disease in England, 2015

2016-12-16T07:03:21-08:00

Objectives

Shiga toxin-producing Escherichia coli (STEC) are zoonotic and transmission to humans occurs via contaminated food or contact with infected animals. In this study, WGS data were used to predict antimicrobial resistance (AMR) in STEC from symptomatic human cases to assess the extent of transmission of antibiotic-resistant E. coli from animals to humans.

Methods

WGS data from 430 isolates of STEC were mapped to genes known to be associated with phenotypic AMR. Susceptibility testing was performed by a breakpoint method on all viable isolates exhibiting resistance to at least one antimicrobial.

Results

327/396 (82.6%) of STEC O157 and 22/34 (64.7%) of STEC O26 lacked identifiable resistance genes and were predicted to be fully susceptible to 11 diverse classes of antimicrobials. For the remaining 81 isolates, 74 were phenotypically tested and there was concordance between WGS-predicted resistance and expression of phenotypic resistance. The most common resistance profile was ampicillin, streptomycin, trimethoprim/sulphonamide and tetracycline occurring in 25 (5.8%) isolates. Resistance to other antimicrobials, including resistance to chloramphenicol (2.1%), resistance to azithromycin (0.2%) and reduced susceptibility to ciprofloxacin (2.6%), was less frequent. Three isolates were identified as ESBL producers.

Conclusions

β-Lactams, trimethoprim/sulphonamides and tetracyclines account for the majority of therapeutic antimicrobials sold for veterinary use and this may be a risk factor for the presence of AMR in domestically acquired human clinical isolates of STEC. Isolates that were resistant to ampicillin, streptomycin, sulphonamide, tetracycline and azithromycin and had reduced susceptibility to ciprofloxacin were associated with cases who reported recent travel abroad.




High-intensity meropenem combinations with polymyxin B: new strategies to overcome carbapenem resistance in Acinetobacter baumannii

2016-12-16T07:03:21-08:00

Objectives

The pharmacodynamics of polymyxin/carbapenem combinations against carbapenem-resistant Acinetobacter baumannii (CRAB) are largely unknown. Our objective was to determine whether intensified meropenem regimens in combination with polymyxin B enhance killing and resistance suppression of CRAB.

Methods

Time–kill experiments for meropenem and polymyxin B combinations were conducted against three polymyxin B-susceptible (MIC of polymyxin B = 0.5 mg/L) CRAB strains with varying meropenem MICs (ATCC 19606, N16870 and 03-149-1; MIC of meropenem = 4, 16 and 64 mg/L, respectively) at 108 cfu/mL. A hollow-fibre infection model was then used to simulate humanized regimens of polymyxin B and meropenem (2, 4, 6 and 8 g prolonged infusions every 8 h) versus N16870 at 108 cfu/mL over 14 days. New mathematical mechanism-based models were developed using S-ADAPT.

Results

Time–kill experiments were well described by the mathematical mechanism-based models, with the presence of polymyxin B drastically decreasing the meropenem concentration needed for half-maximal activity against meropenem-resistant populations from 438 to 82.1 (ATCC 19606), 158 to 93.6 (N16870) and 433 to 76.0 mg/L (03-149-1). The maximum killing effect of combination treatment was similar among all three strains despite divergent meropenem MIC values (Emax = 2.13, 2.08 and 2.15; MIC of meropenem = 4, 16 and 64 mg/L, respectively). Escalating the dose of meropenem in hollow-fibre combination regimens from 2 g every 8 h to 8 g every 8 h resulted in killing that progressed from a >2.5 log10 cfu/mL reduction with regrowth by 72 h (2 g every 8 h) to complete eradication by 336 h (8 g every 8 h).

Conclusion

Intensified meropenem dosing in combination with polymyxin B may offer a unique strategy to kill CRAB irrespective of the meropenem MIC.




Distribution of ESBLs, AmpC {beta}-lactamases and carbapenemases among Enterobacteriaceae isolates causing intra-abdominal and urinary tract infections in the Asia-Pacific region during 2008-14: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART)

2016-12-16T07:03:21-08:00

Objectives

To investigate the antimicrobial resistance and assess the molecular characteristics of β-lactamases (ESBLs, AmpC β-lactamases and carbapenemases) among Enterobacteriaceae isolates that caused intra-abdominal infections (IAIs) in patients hospitalized in the Asia-Pacific region during 2008–14.

Methods

Multiplex PCR was used to detect the specific types of β-lactamase in 2893 isolates with MICs of ertapenem >0.5 mg/L. In-hospital acquisition times for most isolates were also delineated.

Results

Among 2728 (94.3%) isolates proven with β-lactamase production, the rates of non-susceptibility to imipenem were low (average = 7.9%) among IAI Enterobacteriaceae isolates from all Asia-Pacific countries except Vietnam (17.7%) and the Philippines (10.2%). A stepwise and significant increase in annual rates of carbapenemase production among these isolates was noted. CTX-M-15 and CTX-M-14 were the dominant ESBL variants in most IAI Enterobacteriaceae species. The most abundant AmpC β-lactamase variants were blaCMY-2 among isolates of Escherichia coli and blaDHA-1 among isolates of Klebsiella pneumoniae. In addition, the IAI Enterobacteriaceae isolates harbouring a blaCMY-2 or blaDHA-1 allele were associated with high community-acquired rates (38.0% and 42.6%, respectively). AmpC ACT and MIR variants were mostly detected in Enterobacter species. The blaNDM-1,4,5,7-harbouring isolates of E. coli, K. pneumoniae and Enterobacter cloacae were most commonly identified among IAI isolates from Vietnam and the Philippines. Also of note, blaOXA-48-harbouring IAI Enterobacteriaceae isolates were detected exclusively in Vietnam.

Conclusions

The high resistance burden in Vietnam and the Philippines warrants aggressive control policies to combat the worsening trend in antimicrobial resistance among Enterobacteriaceae species causing IAIs.




Impact of bacterial load on pharmacodynamics and susceptibility breakpoints for tigecycline and Klebsiella pneumoniae

2016-12-16T07:03:21-08:00

Objectives

In the absence of other therapeutic options, tigecycline is used to treat bloodstream infections and pneumonia caused by carbapenemase-producing Klebsiella pneumoniae (CP-Kp). In this study, the standard and high tigecycline dosing regimens were simulated and tested against different inocula of CP-Kp isolates in an in vitro pharmacokinetic (PK)/pharmacodynamic (PD) model.

Methods

Four susceptible isolates (EUCAST MICs of 0.125–1 mg/L) and two intermediately susceptible CP-Kp clinical isolates (MICs of 2 mg/L) were tested at three different inocula (107, 105 and 103 cfu/mL), simulating tigecycline serum and lung fCmax concentrations of 0.15 and 1.5 mg/L, respectively, of 50 mg tigecycline every 12 h for 48 h. The exposure–effect relationships were described and the probability of target attainment was calculated for each inoculum in order to determine PK/PD susceptibility breakpoints.

Results

No cfu reduction was observed at serum concentrations. At lung concentrations and low inocula, a bacteriostatic and killing effect was found for isolates with MICs of 0.25 and 0.125 mg/L, respectively. The fAUC0–24/MIC (tAUC0–24/MIC) associated with half-maximal activity was 16 (150) with 103 cfu/mL, 28 (239) with 105 cfu/mL and 79 (590) with 107 cfu/mL. A PK/PD susceptibility breakpoint of ≤0.06 and ≤0.125 mg/L for bacteraemia with ≤101 cfu/mL and ≤0.25 and ≤0.5 mg/L for pneumonia with ≤103 cfu/g was determined for the standard tigecycline dose of 50 mg and the higher dose of 100 mg, respectively.

Conclusions

Tigecycline monotherapy with either 50 or 100 mg would not be sufficient for most patients with bacteraemia, though the higher dose of 100 mg could be effective for patients with pneumonia with low bacterial load.




Population pharmacokinetics of micafungin in ICU patients with sepsis and mechanical ventilation

2016-12-16T07:03:21-08:00

Objectives

To identify the factors associated with the interindividual pharmacokinetic (PK) variability of micafungin and to evaluate the probability of reaching the previously determined PK/pharmacodynamic efficacy thresholds (AUC/MIC >5000 for non-parapsilosis Candida sp. and ≥285 for Candida parapsilosis) with the recommended 100 mg daily dose in ICU patients with sepsis and mechanical ventilation.

Methods

One hundred patients were included and 436 concentrations were available for PK analysis performed with NONMEM software. PTA was determined by Monte Carlo simulations.

Results

Micafungin obeyed a two-compartment model with first-order elimination from the central compartment. Mean parameter estimates (percentage interindividual variability) were 1.34 L/h (34%) for clearance (CL), 11.80 L (38%) and 7.68 L (39%) for central (Vc) and peripheral (Vp) distribution volumes, respectively, and 4.67 L/h (37%) for distribution clearance. CL, Vc and Vp increased by 14% when the albumin level was ≤25 g/L and CL decreased by 25% when SOFA score was ≥10. Body weight was related to CL, Vc and Vp by allometric models. PTA was ≥90% in Candida albicans and Candida glabrata infections, except when the MIC was ≥0.015 mg/L, and ranged between 0% and 40% for C. parapsilosis infections with MIC ≥0.5 mg/L.

Conclusions

A possible increase in the dose should be evaluated for infections due to C. parapsilosis and for infections due to C. albicans and C. glabrata with MICs ≥0.015 mg/L.




Effect of diurnal variation, CYP2B6 genotype and age on the pharmacokinetics of nevirapine in African children

2016-12-16T07:03:21-08:00

Objectives

To characterize the effects of CYP2B6 polymorphisms, diurnal variation and demographic factors on nevirapine pharmacokinetics in African children.

Methods

Non-linear mixed-effects modelling conducted in NONMEM 7.3 described nevirapine plasma concentration–time data from 414 children aged 0.3–15 years.

Results

Nevirapine pharmacokinetics was best described using a one-compartment disposition model with elimination through a well-stirred liver model accounting for a first-pass effect and transit-compartment absorption. Intrinsic clearance was affected by diurnal variation (characterized using a cosine function with peak amplitude 29% at 12 noon) and CYP2B6 metabolizer status [extensive metabolizer (EM) 516GG|983TT, reference; intermediate metabolizer (IM) 516GT|983TT or 516GG|983TC, 17% lower; slow metabolizer (SM) 516TT|983TT or 516GT|983TC, 50% lower; ultra-slow metabolizer (USM) 516GG|983CC, 68% lower]. Age was found to affect pre-hepatic bioavailability: 31.7% lower at birth and increasing exponentially. Median (90% CI) evening Cmin values in the different metabolizer groups were 5.01 (3.01–7.47), 6.55 (3.65–13.32), 11.59 (5.44–22.71) and 12.32 (12.32–27.25) mg/L, respectively. Evening Cmin values were <3 mg/L in 43% of EM weighing <6 kg and 26% of IM weighing <6 kg, while 73% of SM and 88% of USM in all weight-bands had evening Cmin values >8 mg/L. Cmin was not markedly affected by administration time, but was altered by unequal splitting of the daily dose.

Conclusions

Diurnal variation does not greatly affect nevirapine exposure. However, when daily doses cannot be split equally, the larger dose should be given in the morning. To achieve homogeneous exposures, nevirapine doses for SM and USM should be reduced by 50%, and children weighing <6 kg with EM or IM metabolizer status should receive the same dose as children weighing 6–10 kg.




Impact of efavirenz pharmacokinetics and pharmacogenomics on neuropsychological performance in older HIV-infected patients

2016-12-16T07:03:21-08:00

Background

Pharmacokinetics (PK) and pharmacodynamics of efavirenz and its 8-hydroxy metabolite (8-OH-efavirenz) have not been robustly evaluated in older HIV-infected persons.

Objectives

We investigated relationships between neuropsychological (NP) performance and efavirenz and 8-OH-efavirenz PK in HIV-infected individuals >50 years of age.

Methods

A cross-sectional study of HIV-infected adults on an efavirenz-containing regimen. The 12 and 18 h post-dose plasma efavirenz and 8-OH-efavirenz were quantified. CYP2B6 polymorphisms were investigated. Participants underwent neuropsychological tests; surveys were used for depression, sleep quality and anxiety. We investigated potential correlations of efavirenz and 8-OH-efavirenz plasma concentrations with NP performance, sleep, depression, anxiety and CYP2B6 polymorphisms.

Results

Thirty participants (24 men and 6 women) with mean age 57 years (range 50–68). Plasma efavirenz concentrations did not correlate with NP performance; however, higher plasma 8-OH-efavirenz correlated with better learning (P = 0.002), language (P = 0.002) and total NP z-scores (P = 0.003). No correlation was seen for efavirenz or 8-OH-efavirenz with sleep, anxiety or depression. Median 12 and 18 h efavirenz plasma concentrations were 1967 ng/mL (IQR 1476–2394) and 1676 ng/mL (IQR 1120–2062), respectively. Median 12 and 18 h 8-OH-efavirenz plasma concentrations were 378 ng/mL (IQR 223–589) and 384 ng/mL (IQR 216–621), respectively. CYP2B6 G516T was associated with significantly higher plasma efavirenz at 12 and 18 h (P = 0.02) but not worse NP function.

Conclusions

Better neurocognitive functioning was associated with higher 8-OH-efavirenz but not efavirenz plasma concentrations. No correlation was observed with sleep or depression. These findings point to a need for greater understanding of the metabolic profile of efavirenz and 8-OH-efavirenz in plasma and the CNS and relationships with antiviral effect and neurotoxicity.




Integrase strand-transfer inhibitor polymorphic and accessory resistance substitutions in patients with acute/recent HIV infection

2016-12-16T07:03:21-08:00

Objectives

The most recent guidelines suggest using integrase strand-transfer inhibitors (InSTIs) as the preferred antiretroviral regimens for naive HIV-infected individuals. However, resistance to InSTIs is not monitored in many centres at baseline. This study aimed to evaluate the prevalence of InSTI resistance substitutions in newly diagnosed patients with acute/recent HIV infection.

Methods

Genotypic drug resistance tests were performed in all consecutive patients prospectively enrolled with a documented infection of <6 months, from 12 May 2015 to 12 May 2016. Sequences were obtained by high-throughput sequencing.

Results

Five out of 36 consecutive patients (13.89%, 95% CI = 4.67–29.5) with acute/recent HIV infection were detected to have strains carrying InSTI polymorphisms or substitutions conferring low-level resistance to raltegravir and elvitegravir. Four patients had the 157Q polymorphism and one patient had the Q95K substitution. All cases were MSM patients infected with subtype B strains. Viral loads ranged from 2.92 to 6.95 log10 copies/mL. In all cases, the mutational viral load was high. Three patients initiated dolutegravir-based regimens and became undetectable at first viral load control. There were no major viral or epidemiological differences when compared with patients without InSTI substitutions.

Conclusions

Although signature InSTI substitutions (such as Y143R/C, N155H or Q148K/R/H) were not detected, polymorphisms and substitutions conferring low-level resistance to raltegravir and elvitegravir were frequently found in a baseline genotypic test. All cases were infected with subtype B, the most frequent in Europe. In the context of primary HIV infection, virological response should be carefully monitored to evaluate the impact of these InSTI polymorphisms and substitutions.




HIV-1 antiretroviral drug resistance patterns in patients failing NNRTI-based treatment: results from a national survey in South Africa

2016-12-16T07:03:21-08:00

Background

Routine HIV-1 antiretroviral drug resistance testing for patients failing NNRTI-based regimens is not recommended in resource-limited settings. Therefore, surveys are required to monitor resistance profiles in patients failing ART.

Methods

A cross-sectional survey was conducted amongst patients failing NNRTI-based regimens in the public sector throughout South Africa. Virological failure was defined as two consecutive HIV-1 viral load results >1000 RNA copies/mL. Pol sequences were obtained using RT–PCR and Sanger sequencing and submitted to Stanford HIVdb v7.0.1.

Results

A total of 788 sequences were available for analysis. Most patients failed a tenofovir-based NRTI backbone (74.4%) in combination with efavirenz (82.1%) after median treatment duration of 36 months. K103N (48.9%) and V106M (34.9%) were the most common NNRTI mutations. Only one-third of patients retained full susceptibility to second-generation NNRTIs such as etravirine (36.5%) and rilpivirine (27.3%). After M184V/I (82.7%), K65R was the most common NRTI mutation (45.8%). The prevalence of K65R increased to 57.5% in patients failing a tenofovir regimen without prior stavudine exposure. Cross-resistance to NRTIs was often observed, but did not seem to affect the predicted activity of zidovudine as 82.9% of patients remained fully susceptible to this drug.

Conclusions

The introduction of tenofovir-based first-line regimens has dramatically increased the prevalence of K65R mutations in the HIV-1-infected South African population. However, most patients failing tenofovir-based regimens remained fully susceptible to zidovudine. Based on these data, there is currently no need to change either the recommended first- or second-line ART regimens in South Africa.




Structural equation modelling of viral tropism reveals its impact on achieving viral suppression within 6 months in treatment-naive HIV-1-infected patients after combination antiretroviral therapy

2016-12-16T07:03:21-08:00

Objectives

To evaluate the role of pre-treatment co-receptor tropism of plasma HIV on the achievement of viral suppression (plasma HIV RNA 1.69 log10 copies/mL) at the sixth month of combination antiretroviral therapy (cART) in a cohort of naive patients using, for the first time in this context, a path analysis (PA) approach.

Patients and methods

Adult patients with chronic infection by subtype B HIV-1 were consecutively enrolled from the start of first-line cART (T0). Genotypic analysis of viral tropism was performed on plasma and interpreted using the bioinformatic tool Geno2pheno, with a false positive rate of 10%. A Bayesian network starting from the viro-immunological data at T0 and at the sixth month of treatment (T1) was set up and this model was evaluated using a PA approach.

Results

A total of 262 patients (22.1% bearing an X4 virus) were included; 178 subjects (67.9%) achieved viral suppression. A significant positive indirect effect of bearing X4 virus in plasma at T0 on log10 HIV RNA at T1 was detected (P = 0.009), the magnitude of this effect was, however, over 10-fold lower than the direct effect of log10 HIV RNA at T0 on log10 HIV RNA at T1 (P = 0.000). Moreover, a significant positive indirect effect of bearing an X4 virus on log10 HIV RNA at T0 (P = 0.003) was apparent.

Conclusions

PA overcame the limitations implicit in common multiple regression analysis and showed the possible role of pre-treatment viral tropism at the recommended threshold on the outcome of plasma viraemia in naive patients after 6 months of therapy.




Enhanced surveillance of HIV-1 drug resistance in recently infected MSM in the UK

2016-12-16T07:03:21-08:00

Objectives

To determine the prevalence of inferred low-frequency HIV-1 transmitted drug resistance (TDR) in MSM in the UK and its predicted effect on first-line therapy.

Methods

The HIV-1 pol gene was amplified from 442 newly diagnosed MSM identified as likely recently infected by serological avidity testing in 2011–13. The PCR products were sequenced by next-generation sequencing with a mutation frequency threshold of >2% and TDR mutations defined according to the 2009 WHO surveillance drug resistance mutations list.

Results

The majority (75.6%) were infected with subtype B and 6.6% with rare complex or unique recombinant forms. At a mutation frequency threshold of >20%, 7.2% (95% CI 5.0%–10.1%) of the sequences had TDR and this doubled to 15.8% (95% CI 12.6%–19.6%) at >2% mutation frequency (P < 0.0001). The majority (26/42, 62%) of low-frequency variants were against PIs. The most common mutations detected at >20% and 2%–20% mutation frequency differed for each drug class, these respectively being: L90M (n = 7) and M46IL (n = 10) for PIs; T215rev (n = 9) and D67GN (n = 4) for NRTIs; and K103N (n = 5) and G190E (n = 2) for NNRTIs. Combined TDR was more frequent in subtype B than non-B (OR = 0.38; 95% CI = 0.17–0.88; P = 0.024) and had minimal predicted effect on recommended first-line therapies.

Conclusions

The data suggest differences in the types of low-frequency compared with majority TDR variants that require a better understanding of the origins and clinical significance of low-frequency variants. This will better inform diagnostic and treatment strategies.




Different impact of raltegravir versus efavirenz on CD4/CD8 ratio recovery in HIV-infected patients

2016-12-16T07:03:21-08:00

Objectives

A low CD4/CD8 ratio during treated HIV identifies individuals with heightened immunoactivation and excess mortality. Whether ART regimens elicit distinct CD4/CD8 ratio recovery remains unknown. We aimed to compare the efficacy of an integrase inhibitor versus a non-nucleoside to normalize the CD4/CD8 ratio.

Methods

We conducted a post hoc analysis of the STARTMRK study, a randomized, blinded, double-dummy Phase III trial of raltegravir versus efavirenz, and each in combination with tenofovir/emtricitabine, in treatment-naive HIV-infected adults. Blinding was maintained for the entire 5 year duration of the study. Kaplan–Meier methods for time-dependent variables were used to calculate the rates of CD4/CD8 normalization at different cut-offs and cumulative probabilities. Cox proportional hazard models were used to compare probabilities of CD4/CD8 normalization by treatment arm.

Results

A total of 563 patients were analysed; 81% were males and the mean age (SD) was 37 (10) years. Raltegravir was associated with higher rates of CD4/CD8 ratio normalization at the >0.4 cut-off (median time to normalization = 56 versus 84 days; P = 0.048 by log-rank test). A Cox proportional hazard model stratified based on baseline CD4 counts showed an association between raltegravir and higher rates of CD4/CD8 ratio normalization (HR = 1.23; P = 0.02).

Conclusions

We herein show that normalization of the CD4/CD8 ratio above a clinically meaningful threshold may be dependent on the drug class used. Raltegravir showed faster CD4/CD8 ratio normalization compared with efavirenz, a finding with potential clinical implications. Whether other integrase inhibitors have a similar impact for this outcome remains to be explored.




Failure to achieve immunological recovery in HIV-infected patients with clinical and virological success after 10 years of combined ART: role of treatment course

2016-12-16T07:03:21-08:00

Objectives

We assessed factors, including treatment course, associated with failure to obtain a 10 year immunological response after starting first-generation PI-containing combined ART (cART).

Patients and methods

In the prospective COPILOTE cohort of HIV-infected patients started on a first-generation PI-containing regimen in 1997–99, the impact of cART history on the failure to achieve immunological response measured at 10 years was assessed by multivariate logistic regression models in the 399 patients with clinical and virological success of cART.

Results

Failure of CD4 response (CD4 >500/mm3) was associated with age ≥40 years at baseline (P < 0.001), CD4 cell counts ≤500/mm3 at month 4 (P = 0.016) or month 12 (P < 0.001) and ≥3 months of cART interruption (P = 0.016). Factors associated with failure to achieve complete immunological response (CD4 >500/mm3 and CD4:CD8 ratio >1) were CD4:CD8 ratio ≤0.8 at month 8 (P < 0.001) or month 12 (P < 0.001), ≥3 months of cumulative cART interruption (P = 0.011), ≥3 antiretroviral regimens (P = 0.009) and ≤4 treatment lines (P = 0.015). Baseline CD4 and CD4:CD8 ratio were not predictors of the 10 year immunological outcomes.

Conclusions

In this therapeutic cohort of patients starting first-generation PI-containing cART in 1997–99, poor initial immunological response had a negative impact on 10 year CD4 and CD4 plus CD4:CD8 ratio response, despite prolonged virological success. Lack of treatment interruption may improve long-term immunological outcome in HIV infection.




Simplification to dual therapy (atazanavir/ritonavir + lamivudine) versus standard triple therapy [atazanavir/ritonavir + two nucleos(t)ides] in virologically stable patients on antiretroviral therapy: 96 week results from an open-label, non-inferiority, randomized clinical trial (SALT study)

2016-12-16T07:03:21-08:00

Objectives

We evaluated whether maintenance therapy with atazanavir/ritonavir plus lamivudine (ATV/r + 3TC) was non-inferior to ATV/r plus two nucleosides (ATV/r + 2NUCs) at 96 weeks of follow-up.

Methods

SALT is a multicentre, open-label, non-inferiority clinical trial in HIV-1-infected virologically suppressed patients. Hepatitis B virus surface antigen-negative subjects with no previous treatment failure/resistance mutations and HIV-1-RNA <50 copies/mL for ≥6 months were randomized (1 : 1) to ATV/r + 3TC or ATV/r + 2NUCs. The primary endpoint was HIV-1-RNA <50 copies/mL in the PP population. Non-inferiority was demonstrated if the lower bound of the 95% CI for the difference was not below –12%.

Results

Some 286 patients were analysed. At week 96, 74.4% had HIV-1-RNA <50 copies/mL in the ATV/r + 3TC arm versus 73.9% in the ATV/r + 2NUCs arm (95% CI for the difference, –9.9%–11.0%). In both groups, similar values were observed for patients with confirmed virological failure in ATV/r + 3TC versus ATV/r + 2NUCs (9 versus 5), death (1 versus 0), discontinuation due to ART-related toxicity (7 versus 11), withdrawal from the study (7 versus 9) and loss to follow-up (6 versus 6). One patient taking ATV/r + 2NUCs developed resistance mutations (M184V and L63P). Similar values were obtained for change in mean CD4 count [19 versus 18 cells/mm3 (95% CI for the difference, –49.3–50.7), grade 3–4 adverse events (70.7% versus 70.2%) and changes in the global deficit score, –0.3 (95% CI, –0.5 to –0.1) for ATV/r + 3TC, versus –0.2 (95% CI, –0.4 to –0.1) for ATV/r + 2NUCs].

Conclusions

The long-term results of switching to ATV/r + 3TC show that this strategy is effective, safe and non-inferior to ATV + 2NUCs in virologically suppressed HIV-infected patients.




Urinary kidney injury biomarkers and tobramycin clearance among children and young adults with cystic fibrosis: a population pharmacokinetic analysis

2016-12-16T07:03:21-08:00

Background

Tobramycin is frequently used for treatment of bronchopneumonia in patients with cystic fibrosis (CF). Variability in tobramycin clearance (CL) is high in this population with few reliable approaches to guide dosing.

Objectives

We sought to evaluate the pharmacokinetics of once-daily intravenous tobramycin in patients with CF and test the influence of covariates on tobramycin CL, including serum creatinine (SCr) and urinary biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), retinol-binding protein (RBP) and kidney injury molecule-1 (KIM-1).

Methods

This was a prospective, observational cohort study of children/young adults with CF receiving once-daily intravenous tobramycin from October 2012 to May 2014 at Cincinnati Children's Hospital Medical Center. Therapeutic drug monitoring data were prospectively obtained. Population pharmacokinetic analyses were performed using non-linear mixed-effects modelling.

Results

Thirty-seven patients (median age 15.3 years, IQR 12.7–19.5) received 62 tobramycin courses. A one-compartment model with allometrically scaled weight for tobramycin CL and volume of distribution (V) best described the data. Urinary NGAL was associated with tobramycin CL (P < 0.001), as was urinary RBP (P < 0.001). SCr, estimated glomerular filtration rate and urinary KIM-1 were not significant covariates. The population pharmacokinetic parameter estimates were CL = 8.60 L/h/70 kg (relative standard error 4.3%) and V = 31.3 L/70 kg (relative standard error 4.7%).

Conclusions

We describe urinary biomarkers as predictors of tobramycin CL using a population pharmacokinetic modelling approach. Our findings suggest that patient weight and urinary NGAL or RBP could be used to individualize tobramycin therapy in patients with CF.




Voriconazole metabolism is influenced by severe inflammation: a prospective study

2016-12-16T07:03:21-08:00

Background

During an infection or inflammation, several drug-metabolizing enzymes in the liver are down-regulated, including cytochrome P450 iso-enzymes. Since voriconazole is extensively metabolized by cytochrome P450 iso-enzymes, the metabolism of voriconazole can be influenced during inflammation via reduced clearance of the drug, resulting in higher voriconazole trough concentrations.

Objective

To investigate prospectively the influence of inflammation on voriconazole metabolism and voriconazole trough concentrations.

Methods

A prospective observational study was performed at the University Medical Center Groningen. Patients were eligible for inclusion if they were ≥18 years old and treated with voriconazole. Voriconazole and voriconazole-N-oxide concentrations were determined in discarded blood samples. To determine the degree of inflammation, C-reactive protein (CRP) concentrations were used. Subsequently, a longitudinal data analysis was performed to assess the effect of inflammation on the metabolic ratio and voriconazole trough concentration.

Results

Thirty-four patients were included. In total 489 voriconazole trough concentrations were included in the longitudinal data analysis. This analysis showed that inflammation, reflected by CRP concentrations, significantly influenced the metabolic ratio, voriconazole trough concentration and voriconazole-N-oxide concentration (all P < 0.001), when corrected for other factors that could influence voriconazole metabolism. The metabolic ratio was decreased by 0.99229N and the voriconazole-N-oxide concentration by 0.99775N, while the voriconazole trough concentration was increased by 1.005321N, where N is the difference in CRP units (in mg/L).

Conclusions

This study shows that voriconazole metabolism is decreased during inflammation, resulting in higher voriconazole trough concentrations. Therefore, frequent monitoring of voriconazole serum concentrations is recommended during and following severe inflammation.




Efficacy of ceftolozane/tazobactam against urinary tract and intra-abdominal infections caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae: a pooled analysis of Phase 3 clinical trials

2016-12-16T07:03:21-08:00

Objectives

The increase in infections caused by drug-resistant ESBL-producing Enterobacteriaceae (ESBL-ENT) is a global concern. The characteristics and outcomes of patients infected with ESBL-ENT were examined in a pooled analysis of Phase 3 clinical trials of ceftolozane/tazobactam in patients with complicated urinary tract infections (ASPECT-cUTI) and complicated intra-abdominal infections (ASPECT-cIAI).

Methods

Trials were randomized and double blind. The ASPECT-cUTI regimen was 7 days of either intravenous ceftolozane/tazobactam (1.5 g) every 8 h or levofloxacin (750 mg) once daily. The ASPECT-cIAI regimen was 4–14 days of either intravenous ceftolozane/tazobactam (1.5 g) plus metronidazole (500 mg) or meropenem (1 g) every 8 h. Baseline cultures were obtained in both indications. Enterobacteriaceae were selected for ESBL characterization based on predefined criteria and were verified genotypically. Outcomes were assessed at the test-of-cure visit 5–9 days post-therapy in ASPECT-cUTI and 24–32 days post-randomization in ASPECT-cIAI among microbiologically evaluable (ME) patients.

Results

Of 2076 patients randomized, 1346 were included in the pooled ME population and 150 of 1346 (11.1%) had ESBL-ENT at baseline. At US FDA/EUCAST breakpoints of ≤2/≤1 mg/L, 81.8%/72.3% of ESBL-ENT (ESBL-Escherichia coli, 95%/88.1%; ESBL-Klebsiella pneumoniae, 56.7%/36.7%) were susceptible to ceftolozane/tazobactam versus 25.3%/24.1% susceptible to levofloxacin and 98.3%/98.3% susceptible to meropenem at CLSI/EUCAST breakpoints. Clinical cure rates for ME patients with ESBL-ENT were 97.4% (76/78) for ceftolozane/tazobactam [ESBL-E. coli, 98.0% (49 of 50); ESBL-K. pneumoniae, 94.4% (17 of 18)], 82.6% (38 of 46) for levofloxacin and 88.5% (23 of 26) for meropenem.

Conclusions

Randomized trial data demonstrated high clinical cure rates with ceftolozane/tazobactam treatment of cIAI and cUTI caused by ESBL-ENT.




High prevalence of ESBL-producing Escherichia coli and Klebsiella pneumoniae in community-onset bloodstream infections in China

2016-12-16T07:03:21-08:00

Objectives

Community-onset bloodstream infections (COBSIs) caused by ESBL-producing Escherichia coli (ESBL-EC) and ESBL-producing Klebsiella pneumoniae (ESBL-KP) are increasing globally. This study aimed to investigate the epidemiology and risk factors of ESBL-EC and ESBL-KP in COBSIs in China.

Methods

A prospective, multicentre study was performed in 28 tertiary hospitals from September 2013 to November 2014. All isolates and ESBLs were microbiologically characterized. A statistical analysis of risk factors was performed using binary logistic regression. The trial was registered with ClinicalTrials.gov (NCT01961206).

Results

A total of 919 consecutive episodes of COBSIs were reported and 640 E. coli and 279 K. pneumoniae isolates (non-duplicate) were collected. According to the criteria, 662 (72.0%) cases were classified as having community-acquired bloodstream infections, while the remaining 257 (28.0%) were classified as having healthcare-associated bloodstream infections. The proportions of ESBL producers were 55.5% (355/640) among E. coli isolates and 16.5% (46/279) among K. pneumoniae isolates, respectively. Healthcare-associated infections, obstructive urinary tract disease, previous surgical history and use of a cephalosporin antibiotic within 3 months were independent predictors of COBSIs caused by ESBL-EC. Heart failure was the only independent risk factor for COBSIs due to ESBL-KP. Age was not independently associated with infections caused by ESBL producers. CTX-M-14 was the most common ESBL genotype and was widespread throughout the country.

Conclusions

ESBL producers are highly prevalent in COBSIs in China, especially among cases caused by E. coli. For these resistant pathogens, clinicians should consider adequate empirical therapy, and different risk factors for prediction should be used in this country.




Risk factors for resistance to ciprofloxacin in community-acquired urinary tract infections due to Escherichia coli in an elderly population

2016-12-16T07:03:21-08:00

Background

Antimicrobial resistance to ciprofloxacin is rising worldwide, especially in bacteria causing urinary tract infections (UTIs). Prudent use of current antibiotic drugs is therefore necessary.

Objectives

We analysed (modifiable) risk factors for ciprofloxacin-resistant Escherichia coli.

Methods

Urinary cultures of UTIs caused by E. coli were collected from participants in the Rotterdam Study, a prospective cohort study in an elderly population, and analysed for susceptibility to ciprofloxacin. Multivariate logistic regression was performed to investigate several possible risk factors for resistance.

Results

Ciprofloxacin resistance in 1080 E. coli isolates was 10.2%. Multivariate analysis showed that higher age (OR 1.03; 95% CI 1.00–1.05) and use of two (OR 5.89; 95% CI 3.45–10.03) and three or more (OR 3.38; 95% CI 1.92–5.97) prescriptions of fluoroquinolones were associated with ciprofloxacin resistance, while no association between fluoroquinolone use more than 1 year before culture and ciprofloxacin resistance could be demonstrated. Furthermore, a high intake of pork (OR 3.68; 95% CI 1.36–9.99) and chicken (OR 2.72; 95% CI 1.08–6.85) and concomitant prescription of calcium supplements (OR 2.51; 95% CI 1.20–5.22) and proton pump inhibitors (OR 2.04; 95% CI 1.18–3.51) were associated with ciprofloxacin resistance.

Conclusions

Ciprofloxacin resistance in community-acquired UTI was associated with a high intake of pork and chicken and with concomitant prescription of calcium supplements and proton pump inhibitors. Modification of antibiotic use in animals as well as temporarily stopping the prescription of concomitant calcium and proton pump inhibitors need further evaluation as strategies to prevent ciprofloxacin resistance.




Evaluation of empirical treatment for blood culture-negative endocarditis

2016-12-16T07:03:21-08:00

Objectives

Much progress has been made in understanding the main causes of blood culture-negative endocarditis (BCNE). Few studies concerning BCNE treatment (due to previous antibiotics used or fastidious pathogens) are available. We performed this study to evaluate the effectiveness of our therapeutic protocol in BCNE, based on compliance with the protocol, outcome and 1 year mortality.

Patients and methods

We collected prospectively and analysed retrospectively cases of BCNE between 2002 and 2014, using a simplified and standardized protocol developed by our multidisciplinary team. We apply two kinds of protocols to treat BCNE, which include only four intravenous antimicrobial agents: amoxicillin, vancomycin, gentamicin and amphotericin B.

Results

We had 177 patients with definite BCNE. There were 154 (87.0%) patients treated with both appropriate antimicrobial agents and appropriate duration of treatment. We analysed the causes of inappropriate treatment in 13 (7.3%) cases and inappropriate duration in 10 (5.6%) cases. The treatment changes were justified in all cases except one of discharge against medical advice. The fatality rate was 5.1% (nine cases) and all deaths occurred in the group of patients who were treated with appropriate treatment; however, four deaths were not attributable to empirical treatment failure. Concerning the other deaths, the lack of surgical management, in association with empirical treatment, could explain our protocol's failure, such as poorly tolerated surgery.

Conclusions

Our protocol is efficient and our mortality rate was low, compared with the literature review. This may result from a strategy that uses a sampling procedure and a standardized protocol at the same time.




Association between inappropriate empirical antimicrobial therapy and hospital length of stay in Gram-negative bloodstream infections: stratification by prognosis

2016-12-16T07:03:21-08:00

Objectives

The potential benefit from appropriate empirical antimicrobial therapy in patients with favourable prognosis at initial presentation with Gram-negative bloodstream infection (BSI) remains unclear. This retrospective cohort study examined the impact of inappropriate empirical antimicrobial therapy on hospital length of stay (HLOS) following Gram-negative BSI after stratification by predicted prognosis using the BSI mortality risk score (BSIMRS).

Methods

Hospitalized adults with first episodes of Gram-negative BSI from 1 January 2010 to 31 December 2013 at Palmetto Health Hospitals in Columbia, SC, USA were identified. Multivariate Cox proportional hazards regression was used to examine the association between inappropriate empirical antimicrobial therapy and HLOS overall and within each predefined BSIMRS category (<5 and ≥5).

Results

Among 830 unique patients with Gram-negative BSI, 469 and 361 had BSIMRS <5 and ≥5, respectively. Overall, the median age was 65 years, 448 (54%) were women, Escherichia coli (444; 53%) was the most common bloodstream isolate and 444 (53%) had a urinary source of infection. After adjustments in the multivariate model, BSIMRS (HR = 1.14 per point, 95% CI = 1.11–1.17, P < 0.001) and inappropriate empirical antimicrobial therapy (HR = 1.41, 95% CI = 1.07–1.91, P = 0.01) were independently associated with increased risk of remaining hospitalized following Gram-negative BSI. Median HLOS with appropriate and inappropriate empirical antimicrobial therapy was 7 and 10 days, respectively, in patients with BSIMRS <5 (P = 0.03) and 13 and 17 days, respectively, in those with BSIMRS ≥5 (P = 0.02).

Conclusions

Inappropriate empirical antimicrobial therapy is associated with prolonged HLOS following Gram-negative BSI in patients with both good and guarded prognosis.




Antibiotic prescriptions for suspected respiratory tract infection in primary care in South America

2016-12-16T07:03:21-08:00

Objectives

To describe and compare antibiotic prescribing patterns for primary care patients with respiratory tract infections (RTIs) in four South American countries.

Methods

This was a prospective observational study. General practitioners (GPs) from Argentina, Bolivia, Paraguay and Uruguay registered data about all consultations of patients with suspected RTIs in the winter of 2014 (June–August). Variation in antibiotic prescriptions was assessed using a two-level hierarchical logistic model.

Results

Participating GPs (n = 171) registered 11 446 patients with suspected RTI; 3701 (33%) of these received an antibiotic prescription. There was a wide variation across countries in the use and selection of antibiotics. For example, 94% of patients with acute bronchitis were prescribed antibiotics in Bolivia, while in Uruguay only 21% received antibiotics. Amoxicillin was the most commonly prescribed antibiotic across countries, but prescription rates varied between 45% in Bolivia and 69% in Uruguay. Compared with the overall mean prescribing rate, and after adjusting for clinical presentation and demographics, prescribing of antibiotics varied by a factor of 6, the OR ranging from 0.37 (95% CI = 0.21–0.65) in Uruguay to 2.58 (95% CI = 1.66–4) in Bolivia.

Conclusions

The large variation in use and selection of antibiotics across countries is not explained by different patient populations. It could be explained by diagnostic uncertainty and contextual characteristics beyond clinical practice. Reducing uncertainty and country variation requires greater support from the healthcare systems by providing GPs with evidence-based guidelines and tools to apply them.




Patient and public understanding and knowledge of antimicrobial resistance and stewardship in a UK hospital: should public campaigns change focus?

2016-12-16T07:03:21-08:00

Background

The rising global tide of antimicrobial resistance is a well-described phenomenon. Employing effective and innovative antimicrobial stewardship strategies is an essential approach to combat this public health threat. Education of the public and patients is paramount to enable the success of such strategies.

Methods

A panel of hospital multidisciplinary healthcare professionals was set up and a short quiz containing true/false statements around antimicrobial stewardship and resistance was designed and piloted. An educational leaflet with the correct replies and supporting information was also produced and disseminated. Participants were recruited on a single day (18 November 2015) from the hospital outpatient clinics and the hospital outpatient pharmacy waiting room.

Results

One hundred and forty-five completed quizzes were returned, providing a total of 1450 answers. Overall, 934 of 1450 (64%) statements were scored correctly whilst 481 (33%) were scored incorrectly; 35 (3%) statements were left unscored. We speculate that these results may demonstrate that respondents understood the statements, as only a small proportion of statements were left unanswered. The question dealing with the definition of antimicrobial resistance and the question dealing with the definition of antimicrobial stewardship obtained the most incorrect replies (85% and 72%, respectively). However, a specific factual recall question regarding only one microorganism (MRSA) received the most correct responses (99%).

Conclusions

We describe a simple, innovative method of engagement with patients and the general public to help educate and disseminate important public health messages around antimicrobial resistance and stewardship. We also identified the need for public health campaigns to address the knowledge gaps found around this topic.













Behind the scenes of JAC: the publisher's role

2016-11-16T00:26:23-08:00

In this brief article, we focus on Oxford University Press's role as the publisher of the JAC and how it supports authors and readers. The article defines the role of the publisher, as opposed to the Editorial team, Editorial Office or Society owner. It reviews three key functions at the publisher, namely, editorial, production and marketing.




40 years of medical mycology at JAC

2016-11-16T00:26:23-08:00

In the past 40 years, medical mycology has gone from a curiosity in the basements of medical schools to a mainstream branch of clinical microbiology and infectious diseases. Long gone are the days of carefully curated collections of organisms identified purely based on morphology and skill, the lack of therapeutic interventions beyond amphotericin B and the occasional strange case in the ward of a diabetic patient with mucormycosis. We highlight advances in medical mycology as reflected in the past 40 years of JAC.




Therapeutic drug monitoring in the past 40 years of the Journal of Antimicrobial Chemotherapy

2016-11-16T00:26:23-08:00

Since the Journal of Antimicrobial Chemotherapy was first published in 1975, papers addressing therapeutic drug monitoring (TDM) have been a regular feature. Initially they focused on laboratory aspects of drug concentration measurement then they changed more to the application of TDM in a clinical setting. Over its history, the Journal has provided its readership with the latest technological and scientific advances in TDM and has helped to drive changes in TDM that have directly impacted on patient care. These have varied from improvement in the quality of antimicrobial measurements through better identification of dosage regimens and TDM targets that help predict outcome and adverse events. Despite these advances in our understanding of the science and practice of TDM, there remain many areas of uncertainty. As we move into the next 40 years, it is clear that the Journal will continue to provide the readership with the latest science and opinion in this important area.




Mosaic tetracycline resistance genes encoding ribosomal protection proteins

2016-11-16T00:26:23-08:00

First reported in 2003, mosaic tetracycline resistance genes are a subgroup of the genes encoding ribosomal protection proteins (RPPs). They are formed when two or more RPP-encoding genes recombine resulting in a functional chimera. To date, the majority of mosaic genes are derived from sections of three RPP genes, tet(O), tet(W) and tet(32), with others comprising tet(M) and tet(S). In this first review of mosaic genes, we report on their structure, diversity and prevalence, and suggest that these genes may be responsible for an under-reported contribution to tetracycline resistance in bacteria.




A review of treatment modalities for Middle East Respiratory Syndrome

2016-11-16T00:26:23-08:00

The Middle East Respiratory Syndrome coronavirus (MERS-CoV) has been a focus of international attention since its identification in 2012. Epidemiologically it is characterized by sporadic community cases, which are amplified by hospital-based outbreaks. Healthcare facilities in 27 countries from most continents have experienced imported cases, with the most significant outbreak involving 186 cases in Korea. The mortality internationally is 36% and guidance for clinical management has yet to be developed. Most facilities and healthcare providers outside of the Middle East receiving patients have no or little experience in the clinical management of MERS. When a case does occur there is likely little time for a critical appraisal of the literature and putative pharmacological options. We identified published literature on the management of both MERS-CoV and the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) through searches of PubMed and WHO and the US CDC websites up to 30 April 2016. A total of 101 publications were retrieved for critical appraisal. Most published literature on therapeutics for MERS are in vitro experiments, animal studies and case reports. Current treatment options for MERS can be categorized as: immunotherapy with virus-specific antibodies in convalescent plasma; polyclonal and monoclonal antibodies produced in vitro or in genetically modified animals; and antiviral agents. The use of any therapeutics in MERS-CoV remains investigational. The therapeutic agents with potential benefits and warranting further investigation include convalescent plasma, interferon-β/ribavirin combination therapy and lopinavir. Corticosteroids, ribavirin monotherapy and mycophenolic acid likely have toxicities that exceed potential benefits.




Multilevel population genetic analysis of vanA and vanB Enterococcus faecium causing nosocomial outbreaks in 27 countries (1986-2012)

2016-11-16T00:26:23-08:00

Objectives

Vancomycin-resistant Enterococcus faecium (VREfm) have been increasingly reported since the 1980s. Despite the high number of published studies about VRE epidemiology, the dynamics and evolvability of these microorganisms are still not fully understood. A multilevel population genetic analysis of VREfm outbreak strains since 1986, representing the first comprehensive characterization of plasmid content in E. faecium, was performed to provide a detailed view of potential transmissible units.

Methods

From a comprehensive MeSH search, we identified VREfm strains causing hospital outbreaks (1986–2012). In total, 53 VanA and 18 VanB isolates (27 countries, 5 continents) were analysed and 82 vancomycin-susceptible E. faecium (VSEfm) were included for comparison. Clonal relatedness was established by PFGE and MLST (goeBURST/Bayesian Analysis of Population Structure, BAPS). Characterization of van transposons (PCR mapping, RFLP, sequencing), plasmids (transfer, ClaI-RFLP, PCR typing of relaxases, replication-initiation proteins and toxin–antitoxin systems, hybridization, sequencing), bacteriocins and virulence determinants (PCR, hybridization, sequencing) was performed.

Results

VREfm were mainly associated with major human lineages ST17, ST18 and ST78. VREfm and VSEfm harboured plasmids of different families [RCR, small theta plasmids, RepA_N (pRUM/pLG1) and Inc18] able to yield mosaic elements. Tn1546-vanA was mainly located on pRUM/Axe-Txe (USA) and Inc18-pIP186 (Europe) plasmids. The VanB2 type (Tn5382/Tn1549) was predominant among VanB strains (chromosome and plasmids).

Conclusions

Both strains and plasmids contributed to the spread and persistence of vancomycin resistance among E. faecium. Horizontal gene transfer events among genetic elements from different clonal lineages (same or different species) result in chimeras with different stability and host range, complicating the surveillance of epidemic plasmids.




Emergence of endemic MLST non-typeable vancomycin-resistant Enterococcus faecium

2016-11-16T00:26:23-08:00

Background

Enterococcus faecium is a major nosocomial pathogen causing significant morbidity and mortality worldwide. Assessment of E. faecium using MLST to understand the spread of this organism is an important component of hospital infection control measures. Recent studies, however, suggest that MLST might be inadequate for E. faecium surveillance.

Objectives

To use WGS to characterize recently identified vancomycin-resistant E. faecium (VREfm) isolates non-typeable by MLST that appear to be causing a multi-jurisdictional outbreak in Australia.

Methods

Illumina NextSeq and Pacific Biosciences SMRT sequencing platforms were used to determine the genome sequences of 66 non-typeable E. faecium (NTEfm) isolates. Phylogenetic and bioinformatics analyses were subsequently performed using a number of in silico tools.

Results

Sixty-six E. faecium isolates were identified by WGS from multiple health jurisdictions in Australia that could not be typed by MLST due to a missing pstS allele. SMRT sequencing and complete genome assembly revealed a large chromosomal rearrangement in representative strain DMG1500801, which likely facilitated the deletion of the pstS region. Phylogenomic analysis of this population suggests that deletion of pstS within E. faecium has arisen independently on at least three occasions. Importantly, the majority of these isolates displayed a vancomycin-resistant genotype.

Conclusions

We have identified NTEfm isolates that appear to be causing a multi-jurisdictional outbreak in Australia. Identification of these isolates has important implications for MLST-based typing activities designed to monitor the spread of VREfm and provides further evidence supporting the use of WGS for hospital surveillance of E. faecium.




Characterization of a novel staphylococcal cassette chromosome composite island from community-associated MRSA isolated in aged care facilities in Western Australia

2016-11-16T00:26:23-08:00

Background

In Western Australia (WA), clonal complex 5, ST835, community-associated (CA) MRSA is isolated almost exclusively from aged care facilities. In WA four different staphylococcal cassette chromosome (SCC) mec (SCCmec) elements have been identified in this ST, indicating high genetic activity in the SCCmec region.

Objectives

To investigate the SCC region of ST835 CA-MRSA WA MRSA-40 and determine the distribution of an SCCsorbitol element found within the region.

Results

The SCC region contained a composite island, SCCmecWA MRSA-40-CI, that was composed of three elements, SCCpls, SCCsorbitol and SCCmecVT (5C2&5). This is the first time that a sorbitol operon has been reported in an SCC element.

Conclusions

Generation of SCCmecWA MRSA-40-CI has involved multiple genetic events and recombination with CoNS has occurred during evolution of the SCC elements. While Staphylococcus aureus is renowned for its ability to utilize mobile genetic elements to disseminate antimicrobial resistance, the SCC region of WA MRSA-40 shows that this clone has also utilized SCC elements to acquire extra virulence and possibly adapt to a niche environment.




Description and characterization of a penicillin-resistant Streptococcus dysgalactiae subsp. equisimilis clone isolated from blood in three epidemiologically linked patients

2016-11-16T00:26:23-08:00

Background

During a 27 month period, we detected four incidents of penicillin-resistant (PR) Streptococcus dysgalactiae subsp. equisimilis (SDSE) isolated from blood cultures of three patients.

Methods

The 4 PR-SDSE were compared phenotypically and molecularly (using WGS) with 36 penicillin-susceptible SDSE from blood cultures obtained in the same catchment area and time period.

Results

Phylogenetic analysis showed that the four PR-SDSE belonged to a single clone and a possible epidemiological link between the three patients was identified to be a dermatology department. MICs of penicillin were determined to be 0.5–2 mg/L using Etest and 0.5 mg/L when tested by a broth microdilution method. The four PR-SDSE were unrelated to the 36 penicillin-susceptible isolates, which could suggest that they did not evolve locally from a susceptible clone, but have been introduced into the region. In silico genome-based resistome analysis revealed identical PBP mutations in all four isolates. We detected mutations in multiple PBPs, including two amino acid substitutions within the active sites of the transpeptidase domain of PBP2x (T341P and Q555E), which have also been detected in other PR streptococci. The remaining mutations were, however, all located outside the active-site motifs of the transpeptidase domain.

Conclusions

To the best of our knowledge, this is the first description and characterization of invasive PR-SDSE. The resistant isolates had several amino acid changes in various PBPs compared with penicillin-susceptible SDSE. The observation that SDSE also can become PR emphasizes the importance of performing antimicrobial susceptibility testing.




Multiplication of blaOXA-23 is common in clinical Acinetobacter baumannii, but does not enhance carbapenem resistance

2016-11-16T00:26:23-08:00

Objectives

To investigate the copy number of blaOXA-23 and its correlation with carbapenem resistance in carbapenem-resistant Acinetobacter baumannii (CRAB).

Methods

A total of 113 blaOXA-23-positive clinical CRAB isolates were collected from two hospitals in Zhejiang province, China. Their genetic relatedness was determined by MLST. The MIC of imipenem was determined using the agar diffusion method and the copy number of blaOXA-23 was measured using quantitative real-time PCR (qRT-PCR). The complete genomes of five clinical CRAB strains were sequenced using PacBio technology to investigate the multiplication mechanism of blaOXA-23.

Results

Most of the isolates (100/113) belonged to global clone II and the MIC of imipenem ranged from 16 to 96 mg/L. The gene blaOXA-23 resided exclusively in Tn2006 or Tn2009. Approximately 38% of the isolates carried two or more copies of blaOXA-23. The copy number of blaOXA-23 was not correlated with the MIC of imipenem. Within the five sequenced strains, multiple copies of blaOXA-23 were either tandemly clustered or independently inserted at different genomic sites.

Conclusions

Multiplication of blaOXA-23 is common in CRAB, but does not enhance carbapenem resistance. Multiplication can be present in the form of either tandem amplifications or independent insertions at different sites.




Molecular epidemiology of KPC-producing Klebsiella pneumoniae from invasive infections in Italy: increasing diversity with predominance of the ST512 clade II sublineage

2016-11-16T00:26:23-08:00

Objectives

The spread of carbapenem-resistant Enterobacteriaceae (CRE) represents one of the most worrisome problems for clinical medicine worldwide. In Italy, the Antibiotic-Resistance-Istituto Superiore di Sanità surveillance network, in collaboration with the Committee for Antimicrobial Agents of the Italian Society of Clinical Microbiologists, promoted a study to investigate the carbapenem-resistance mechanisms, clonal relatedness and capsular typing of a recent collection of carbapenem-resistant Klebsiella pneumoniae (CR-KP).

Methods

A total of 17 laboratories distributed across Italy collected all consecutive non-replicate CR-KP isolated from invasive infections during two different study periods (2011–12 and 2013). Carbapenemase genes were searched for by filter hybridization and confirmed by PCR and sequencing. KPC-producing K. pneumoniae (KPC-KP) were typed by PFGE and MLST. Capsular types were identified by wzi gene typing.

Results

Of the collected K. pneumoniae isolates (n = 461), the overall proportion of CR-KP was 36.2% (n = 167). The majority (97%) of the CR-KP were positive for the blaKPC gene. Among the KPC-KP population, nine different STs were detected with the majority of isolates (94%) belonging to the clonal group (CG) 258. A subpopulation that belonged to ST512 and showed an identical PFGE profile represented the majority (57%) of KPC-KP strains, with a countrywide distribution. Capsular characterization showed the predominance of the wzi154, cps-2 capsular type (88.8% of all CG258 strains). ST258 strains were associated with both cps-1 and cps-2 capsular types, while ST512 was associated with cps-2 only.

Conclusions

Although a trend to a polyclonal evolution of the Italian KPC-KP was noted, this study showed that the KPC-KP population remained largely oligoclonal with the wide diffusion of an ST512 lineage carrying cps-2 capsular type and producing the KPC-3 enzyme.




The spread of KPC-producing Enterobacteriaceae in Spain: WGS analysis of the emerging high-risk clones of Klebsiella pneumoniae ST11/KPC-2, ST101/KPC-2 and ST512/KPC-3

2016-11-16T00:26:23-08:00

Objectives

We analysed the microbiological traits and population structure of KPC-producing Enterobacteriaceae isolates collected in Spain between 2012 and 2014. We also performed a comparative WGS analysis of the three major KPC-producing Klebsiella pneumoniae clones detected.

Methods

Carbapenemase and ESBL genes were sequenced. The Institut Pasteur MLST scheme was used. WGS data were used to construct phylogenetic trees, to identify the determinants of resistance and to de novo assemble the genome of one representative isolate of each of the three major K. pneumoniae clones.

Results

Of the 2443 carbapenemase-producing Enterobacteriaceae isolates identified during the study period, 111 (4.5%) produced KPC. Of these, 81 (73.0%) were K. pneumoniae and 13 (11.7%) were Enterobacter cloacae. Three major epidemic clones of K. pneumoniae were identified: ST11/KPC-2, ST101/KPC-2 and ST512/KPC-3. ST11/KPC-2 differed from ST101/KPC-2 and ST512/KPC-3 by 27 819 and 6924 SNPs, respectively. ST101/KPC-2 differed from ST512/KPC-3 by 28 345 SNPs. Nine acquired resistance genes were found in ST11/KPC-2, 11 in ST512/KPC-3 and 13 in ST101/KPC-2. ST101/KPC-2 had the highest number of virulence genes (20). An 11 bp deletion at the end of the mgrB sequence was the cause of colistin resistance in ST512/KPC-3.

Conclusions

KPC-producing Enterobacteriaceae are increasing in Spain. Most KPC-producing K. pneumoniae isolates belonged to only five clones: ST11 and ST512 caused interregional spread, ST101 caused regional spread and ST1961 and ST678 produced independent hospital outbreaks. ST101/KPC-2 had the highest number of resistance and virulence genes. ST101/KPC-2 and ST512/KPC-3 were recently implicated in the spread of KPC in Italy.




WGS for surveillance of antimicrobial resistance: a pilot study to detect the prevalence and mechanism of resistance to azithromycin in a UK population of non-typhoidal Salmonella

2016-11-16T00:26:23-08:00

Objectives

WGS and phenotypic methods were used to determine the prevalence of azithromycin resistance in Salmonella enterica isolates from the UK and to identify the underlying mechanisms of resistance.

Methods

WGS by Illumina HiSeq was carried out on 683 Salmonella spp. isolates. Known genes associated with azithromycin resistance were detected by WGS using a mapping-based approach. Macrolide resistance determinants were identified and the genomic context of these elements was assessed by various bioinformatics tools. Susceptibility testing was in accordance with EUCAST methodology (MIC ≤16 mg/L).

Results

Fifteen isolates of non-typhoidal Salmonella enterica belonging to serovars Salmonella Blockley, Salmonella Typhimurium, Salmonella Thompson, Salmonella Ridge and Salmonella Kentucky showed resistance or decreased susceptibility to azithromycin (from 6 to >16 mg/L) due to the presence of macrolide resistance genes mphA, mphB or mefB. These genes were either plasmid or chromosomally mediated. Azithromycin-resistant Salmonella Blockley isolates harboured a macrolide inactivation gene cluster, mphA-mrx-mphr(A), within a novel Salmonella azithromycin resistance genomic island (SARGI) determined by MinION sequencing. This is the first known chromosomally mediated mphA gene cluster described in salmonellae. Phylogenetic analysis and epidemiological information showed that mphA Salmonella Blockley isolates were not derived from a single epidemiologically related event. The azithromycin MICs of the 15 Salmonella spp. isolates showed that the presence of the mphA gene was associated with MIC ≥16 mg/L, while the presence of mefB or mphB was not.

Conclusions

Azithromycin resistance due to acquisition of known macrolide resistance genes was seen in four different Salmonella serovars and can be either plasmid-encoded or chromosomally encoded.




Salmonella Typhimurium exhibits fluoroquinolone resistance mediated by the accumulation of the antioxidant molecule H2S in a CysK-dependent manner

2016-11-16T00:26:23-08:00

Objectives

To evaluate the contribution of cysK and cysM to the fluoroquinolone (ofloxacin) antibiotic resistance in Salmonella Typhimurium, and their impact on H2S and cysteine production through targeted mutagenesis.

Methods

Salmonella Typhimurium 14028s and its cysK and cysM mutants were tested for their susceptibility to ofloxacin, as determined by a broth microdilution test (to determine the MIC) and survival curves. H2S levels were measured by the Pb(AC)2 method and cysteine levels were determined using 5,5-dithio-bis-2-nitrobenzoic acid. DNA damage induced by antibiotic treatment was determined by PFGE. Finally, expression of cysK and cysM genes under antibiotic treatment was determined by real-time reverse transcription PCR.

Results

As determined by MIC, the cysK strain was more resistant to ofloxacin, a reactive oxygen species (ROS)-producing fluoroquinolone, than the WT and cysM strains, which correlates with survival curves. Moreover, the cysK strain exhibited higher H2S levels and lower cysteine levels than the WT strain. Finally, the cysK strain exhibited lower DNA damage upon challenge with ofloxacin than the WT and cysM strains. These results are in accordance with lower expression of cysK under ofloxacin treatment in the WT strain.

Conclusions

This work demonstrated that cysteine metabolism in Salmonella Typhimurium modulated H2S levels, conferring resistance to second-generation fluoroquinolones.




Detection of the plasmid-mediated colistin-resistance gene mcr-1 in faecal metagenomes of Dutch travellers

2016-11-16T00:26:23-08:00

Background

Recently, the first plasmid-mediated colistin-resistance gene, mcr-1, was reported. Colistin is increasingly used as an antibiotic of last resort for the treatment of infections caused by carbapenem-resistant bacteria, which have been rapidly disseminating worldwide in recent years.

Objectives

The reported carriage rate of mcr-1 in humans remains sporadic thus far, except for those reported in Chinese populations. We aimed to determine its presence in the faecal metagenomes of healthy Dutch travellers between 2010 and 2012.

Methods

Faecal metagenomic DNA of pre- and post-travel samples from 122 healthy Dutch long-distance travellers was screened for the presence of mcr-1 using a TaqMan quantitative PCR assay, which was designed in this study. All positive samples were confirmed by sequencing of the amplicons.

Results

The mcr-1 gene was detected in 6 (4.9%, 95% CI = 2.1%–10.5%) of 122 healthy Dutch long-distance travellers after they had visited destinations in South(-east) Asia or southern Africa between 2011 and 2012. One of these participants was already found to be positive before travel.

Conclusions

Our study highlights the potential of PCR-based targeted metagenomics as an unbiased and sensitive method to screen for the carriage of the mcr-1 gene and suggests that mcr-1 is widespread in various parts of the world. The observation that one participant was found to be positive before travel suggests that mcr-1 may already have disseminated to the microbiomes of Dutch residents at a low prevalence, warranting a more extensive investigation of its prevalence in the general population and possible sources.




Evaluation of a novel procedure for rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) using the LightMix(R) modular carbapenemase kits

2016-11-16T00:26:23-08:00

Objectives

Evaluation of the LightMix® modular carbapenemase kits for the rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) and the application of these kits to the direct detection of colonized patients and bacteraemias.

Methods

The modular multiplex PCR kits targeting blaKPC, blaNDM, blaVIM, blaIMP and blaOXA-48-like carbapenem resistance genes were evaluated in terms of sensitivity and specificity for carbapenemase resistance in a set of 118 labelled clinical isolates. Among these, 96 were CPE genotypically characterized by PCR and sequencing. The limits of detection were calculated for the different carbapenem resistance genes in terms of cfu/mL. In addition, the kits were used to evaluate colonization of patients by CPE by comparing this assay with the Xpert® Carba-R Kit on 127 rectal, perirectal and pharyngeal samples. Blood cultures from bacteraemias (4) and spiked blood cultures (23) with genotypically characterized isolates were also evaluated.

Results

The overall sensitivity and specificity of the multiplex PCR assay was 99% and 100%, respectively. The limit of detection for blaKPC, blaVIM, blaIMP and blaOXA-48-like is 60 cfu/mL and for blaNDM 500 cfu/mL. The colonization and bacteraemia studies revealed a 100% agreement between the results obtained by this assay and the ones obtained by GeneXpert®.

Conclusions

The LightMix® modular carbapenemase kits are highly reliable and utilizable assays for both colonized and septic patients, and can help in the improvement of infection control. Their modular design facilitates cost-effective detection of CPE in hospital settings.




Evaluation of the Scan(R) 1200 as a rapid tool for reading antibiotic susceptibility testing by the disc diffusion technique

2016-11-16T00:26:23-08:00

Objectives

In clinical microbiology, some instruments are able to automatically read inhibition zone diameters for antibiotic susceptibility testing (AST) performed by the disc diffusion (DD) method. The actual resolution of commercial reader systems is low and high-resolution scanners have been developed for microbiology. Here, we evaluated and compared the reading and interpretation of AST by the DD method using the Scan® 1200 instrument as compared with the Sirscan® system on 211 clinical strains and the possibility to read AST after 6 or 8 h of incubation as compared with 24 h on 121 additional Gram-negative strains and 76 non-fermenter Gram-negative and Gram-positive strains.

Methods

Validation of the technique was assessed on three reference strains as requested by EUCAST for analysis of the repeatability and reproducibility of the method.

Results

Correlation between the two methods, assessed using 211 clinical isolates (n = 2439 zones of growth inhibition measured), was excellent with a correlation coefficient of 0.97. For the earlier reading experiments, preliminary results demonstrate the possibility of reading AST for drug–species combinations after 6 and 8 h for Gram-negative bacteria with rapid growth (correlation coefficient at 6 h = 0.96 and at 8 h = 0.98) and at 8 or 10 h for Gram-positive bacteria.

Conclusions

The Scan® 1200 has many advantages thanks to its small size, rapidity of use and high-resolution imaging allowing the possibility to improve AST results after only 6–8 h of incubation. This AST reader system represents a robust alternative tool for routine use in clinical microbiology laboratories.




Identification of inhibitors for single-stranded DNA-binding proteins in eubacteria

2016-11-16T00:26:23-08:00

Objectives

The increasing threat of drug-resistant bacteria establishes a continuing need for the development of new strategies to fight infection. We examine the inhibition of the essential single-stranded DNA-binding proteins (SSBs) SSBA and SSBB as a potential antimicrobial therapy due to their importance in DNA replication, activating the SOS response and promoting competence-based mechanisms of resistance by incorporating new DNA.

Methods

Purified recombinant SSBs from Gram-positive (Staphylococcus aureus and Bacillus anthracis) and Gram-negative (Escherichia coli and Francisella tularensis) bacteria were assessed in a high-throughput screen for inhibition of duplex DNA unwinding by small molecule inhibitors. Secondary electrophoretic mobility shift assays further validated the top hits that were then tested for MICs using in vitro assays.

Results

We have identified compounds that show cross-reactivity in vitro, as well as inhibition of both F. tularensis and B. anthracis SSBA. Five compounds were moderately toxic to at least two of the four bacterial strains in vivo, including two compounds that were selectively non-toxic to human cells, 9-hydroxyphenylfluoron and purpurogallin. Three of the SSBA inhibitors also inhibited S. aureus SSBB in Gram-positive bacteria.

Conclusions

Results from our study support the potential for SSB inhibitors as broad-spectrum antibacterial agents, with dual targeting capabilities against Gram-positive bacteria.




In vitro activity of SecA inhibitors in combination with carbapenems against carbapenem-hydrolysing class D {beta}-lactamase-producing Acinetobacter baumannii

2016-11-16T00:26:23-08:00

Objectives

According to our previous study, OXA-58 translocates to the periplasm via the Sec pathway in carbapenem-resistant Acinetobacter baumannii (CRAb). In the present study, carbapenem-hydrolysing class D β-lactamases (CHDLs) belonging to the OXA-23, OXA-40 and OXA-51 families were examined to determine whether they are also Sec-dependent. Additionally, the effects of SecA inhibitors combined with carbapenems against CHDL-producing CRAb were examined.

Methods

Cell fractionation and western blot analyses were performed to detect periplasmic His-tagged CHDLs. A chequerboard analysis with pairwise combinations of carbapenems (imipenem or meropenem) and SecA inhibitors (rose bengal, sodium azide or erythrosin B) was performed using six clinical CRAb isolates harbouring different CHDL genes. The fractional inhibitory concentration (FIC) index was determined. The combination with the lowest FIC index was subjected to a time–kill analysis to examine synergistic effects.

Results

In an in silico analysis, the CHDLs OXA-23, OXA-40 and OXA-51 were preferentially translocated via the Sec system. The SecA inhibitor rose bengal decreased periplasmic translocation of His-tagged OXA-23 and OXA-83 (belonging to the OXA-51 family), but not OXA-72 (belonging to the OXA-40 family) from ATCC 15151 transformants. Imipenem or meropenem with rose bengal showed synergistic effects (FIC index, ≤0.5) for six and four clinical isolates, respectively. Imipenem or meropenem with sodium azide showed no interactions (FIC index, 0.5–4) against all clinical isolates. Imipenem and rose bengal had the lowest FIC index and showed synergy at 24 h in the time–kill assay.

Conclusions

Combinations of SecA inhibitors and carbapenems have synergistic effects against CHDL-producing CRAb.




In vitro activity of anidulafungin in combination with amphotericin B or voriconazole against biofilms of five Candida species

2016-11-16T00:26:23-08:00

Objectives

To evaluate the in vitro activity of anidulafungin combined with amphotericin B or voriconazole against Candida spp. biofilms.

Methods

Four Candida albicans, four Candida tropicalis, four Candida glabrata, two Candida parapsilosis and two Candida orthopsilosis blood isolates were tested by the microdilution chequerboard method combined with the XTT metabolic assay. Biofilm MIC was defined as the lowest concentration producing 50% metabolic inhibition with respect to control (BMIC50). Concentrations in the combinations ranged from 1/8 x BMIC50 to 4 x BMIC50 found for each antifungal tested alone.

Results

Anidulafungin plus amphotericin B acted synergistically against C. albicans and C. glabrata biofilms [fractional inhibitory concentration index (FICI): 0.082–0.387], but showed no interaction against C. tropicalis, C. parapsilosis and C. orthopsilosis (FICI: 0.516–2.099). The combination of these antifungals failed to completely remove biofilms of C. albicans and C. glabrata, decreasing the metabolic activity of the biofilms up to 80% and 95%, respectively, which did not occur when each antifungal was used alone. Anidulafungin plus voriconazole showed no interaction against all isolates. Using a less stringent criterion previously proposed to define synergism (FICI < 1) and antagonism (FICI > 1.25), antagonistic interactions were found against some isolates.

Conclusions

Anidulafungin with amphotericin B results in a synergistic effect against C. albicans and C. glabrata biofilms at serum concentrations of the drugs, but showed no interaction against C. tropicalis and C. parapsilosis complex. Anidulafungin plus voriconazole showed no interaction against the five Candida species assayed. Biofilms of C. tropicalis were found to be the most resistant towards the combinations assayed. The results presented may be of potential interest in the clinical setting.




Longitudinal (2001-14) analysis of enterococci and VRE causing invasive infections in European and US hospitals, including a contemporary (2010-13) analysis of oritavancin in vitro potency

2016-11-16T00:26:23-08:00

Objectives

The objective of this study was to evaluate the prevalence and in vitro susceptibility of enterococci and VRE among bloodstream infections in European and US hospitals over time.

Methods

Isolates recovered from the blood of infected patients in Europe (72 996) and the USA (67 725) between 2001 and 2014 were included in the prevalence analysis. A subset (2349) collected during 2011–13 was used for the in vitro activity analysis.

Results

Enterococcus faecium rates increased in Europe (from 1.4% in 2001 to 4.3% in 2014). These rates also increased in the USA (from 3.0% in 2001 to 5.4% in 2010), with decreasing prevalence (4.6% in 2011 to 3.6% in 2014) in later years. Enterococcus faecalis rates remained stable in Europe, but rose in the USA from 6.9% in 2001 to 8.8% in 2009, declining later (from 7.4% to 5.0%). VRE rates among E. faecalis did not vary in either region, while VRE rates among E. faecium increased in Europe (from 4.7% to 20.3%). US VRE rates among E. faecium increased until 2010 (60.0% in 2001 to 80.7% in 2010), decreasing from 75.1% in 2011 to 68.4% in 2013. Oritavancin demonstrated activity against vancomycin-susceptible E. faecalis (MIC50/90, 0.015/0.06 mg/L; 99.5% susceptible) and vancomycin-resistant E. faecalis (MIC50/90, 0.25/0.5 mg/L). Oritavancin showed MIC50, MIC90 and MIC100 values of 0.03, 0.12 and 0.25 mg/L, respectively, for VanA E. faecium.

Conclusions

Rates of E. faecium and VRE increased in Europe. Although still elevated, VRE rates appeared to show a decreasing trend in the USA since 2010. Oritavancin demonstrated activity against enterococci, including VRE.




Comparative in vitro activities of ceftaroline and ceftriaxone against bacterial pathogens associated with respiratory tract infections: results from the AWARE surveillance study

2016-11-16T00:26:23-08:00

Objectives

Ceftaroline fosamil is indicated for the treatment of community-acquired bacterial pneumonia and ceftriaxone has an indication for lower respiratory tract infections. This study was conducted to compare the relative in vitro activities of these two agents against bacterial species associated with community-associated respiratory tract infections.

Methods

In all, 13 005 isolates of Staphylococcus aureus, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae were collected in 2012–14 from 39 countries in the Asia–Pacific region, Europe, Latin America and Africa–Middle East from respiratory tract specimens. The identification was confirmed centrally by MALDI-TOF and broth microdilution susceptibility testing and interpretation was done according to CLSI guidelines.

Results

Ceftaroline was 16-fold more potent against MSSA (MIC90 0.25 versus 4 mg/L) than ceftriaxone and ≥16-fold more potent against MRSA (MIC90 2 versus >32 mg/L). Ceftaroline was 16-fold more potent against S. pneumoniae (MIC90 0.12–0.25 mg/L) compared with ceftriaxone (MIC90 1–2 mg/L), with higher MIC values observed among penicillin-non-susceptible isolates for both agents. Similar activity (MIC90 ≤0.03 mg/L) was observed for ceftaroline and ceftriaxone against H. influenzae, with higher MIC values observed in the Asia–Pacific region for both agents compared with other regions. Ceftaroline was 4- to 8-fold more active against M. catarrhalis (MIC90 0.12–0.25 mg/L) compared with ceftriaxone (MIC90 1 mg/L).

Conclusions

These global MIC data demonstrated that ceftaroline exhibited superior in vitro activity compared with ceftriaxone against bacterial species that commonly cause community-associated respiratory tract infections.




In vivo Mycobacterium tuberculosis fluoroquinolone resistance emergence: a complex phenomenon poorly detected by current diagnostic tests

2016-11-16T00:26:23-08:00

Objectives

Heteroresistance, described both in terms of various point mutations resulting in different levels of resistance and in terms of a mixture of mutant and WT bacilli, is identified in up to one-third of fluoroquinolone (FQ)-resistant Mycobacterium tuberculosis isolates. Heteroresistance is a challenge for current phenotypic and genotypic susceptibility testing (DST) regimes. We aimed to compare the performances of different phenotypic and genotypic DST in the context of FQ heteroresistance by mimicking, in a murine model, the course of selection of FQ resistance during treatment.

Methods

The capacity of different phenotypic DST [Lowenstein–Jensen (LJ) medium containing either 2 mg/L ofloxacin or 0.5, 1 or 2 mg/L moxifloxacin] and genotypic DST (gyrA/B Sanger sequencing) to detect FQ resistance was analysed.

Results

Ninety-seven percent of mice harboured a heterogeneous population. The proportion of mice in which FQ resistance was detected varied according to the medium used (97% for 0.5 mg/L moxifloxacin, 80% for 2 mg/L ofloxacin, 47% for 1 mg/L moxifloxacin and 25% for 2 mg/L moxifloxacin). Compared with phenotypic DST, genotypic DST had a low sensitivity for detection of resistance (33%).

Conclusions

Our study shows the in vivo complexity of FQ resistance emergence and the poor sensitivity of Sanger DNA sequencing for detection of heteroresistance. Our data support the use of 0.5 mg/L moxifloxacin in LJ for detection of FQ resistance, but not the recent increase in the ofloxacin critical concentration from 2 to 4 mg/L given in the WHO recommendations.




Assessment of antivirulence activity of several D-amino acids against Acinetobacter baumannii and Pseudomonas aeruginosa

2016-11-16T00:26:23-08:00

Objectives

Biofilm formation and bacterial adherence are important requirements for persistence, multidrug resistance and infection. The d-amino acids play a role as modulators of bacterial growth and persistence, though their ability to inhibit biofilms is much debated. In this study, we analysed the effects of 18 different d-amino acids on the pathogens Acinetobacter baumannii and Pseudomonas aeruginosa.

Methods

In vitro assays were carried out to analyse the effect of d-amino acids on bacterial growth, biofilm formation/disassembly, capacity to attach to eukaryotic cells and cellular death. In addition, in vivo assays were performed in mice, using experimental models of sepsis and pneumonia.

Results

Biofilm formation was inhibited in A. baumannii by d-His, d-Cys and d-Trp (35%–86%) at 2 mM and in P. aeruginosa by d-Cys, d-Trp and d-Tyr (10%–30%) at 4 mM. Attachment to the A549 human alveolar cells was reduced in A. baumannii by d-Cys, d-His, d-Met, d-Val and d-Ser, and in P. aeruginosa by d-Arg and d-Trp. Growth was inhibited in A. baumannii by d-Cys and d-Trp, and in P. aeruginosa by d-Trp. In virulence assays, incubation of alveolar cells infected with P. aeruginosa with d-Cys, d-Trp and d-Arg reduced cell death (56%–45%). However, no significant effect of d-amino acids was observed in vivo.

Conclusions

Some d-amino acids can inhibit bacterial growth, biofilm formation and adherence to eukaryotic cells in A. baumannii and P. aeruginosa, and showed a protective effect against infection of alveolar cells with P. aeruginosa. Despite the fact that some considerable protection was observed in mice, survival differences between treated and control groups were not statistically significant.




Pharmacokinetics of high-dose nebulized amikacin in ventilated critically ill patients

2016-11-16T00:26:23-08:00

Background

Antibiotic nebulization theoretically allows the delivery of high doses to the lungs together with limited systemic exposure and toxicity. This study aimed to describe amikacin pharmacokinetics, and especially its absorption, in patients treated with high-dose nebulized amikacin.

Patients and methods

Twenty critically ill patients experiencing ventilator-associated pneumonia received a 20 mg/kg infusion of amikacin, followed by either three other infusions or three nebulizations of 60 mg/kg amikacin. An extensive sampling regimen allowed measurement of amikacin serum concentrations at 0.5, 1, 1.5, 2, 3, 4, 6, 10 and 24 h after each administration. Amikacin pharmacokinetics was studied by population compartmental modelling.

Results

Amikacin pharmacokinetics was best described using a two-compartment structural model with first-order distribution and elimination, in which lung absorption was described using a transit model. Estimated means (interindividual variability) of the main parameters were: bioavailability F = 2.65% (22.1%); transit compartments n = 1.58 (fixed); transit constant ktr = 1.38 h–1 (33.4%); central volume Vc = 10.2 L (10.5%); and elimination constant k10 = 0.488 h–1 (35.8%). The addition of interoccasion variability on F (44.0%) and k10 (41.7%) allowed the description of intraindividual variability of bioavailability and elimination. Amikacin clearance was positively correlated with baseline creatinine clearance.

Conclusions

Our pharmacokinetic model provided an accurate description of amikacin concentrations following nebulization. There was wide interindividual and interoccasion variability in the absorption and elimination of amikacin. Nevertheless, systemic exposure after nebulization was always much lower than after infusion, an observation suggesting that nebulized high doses are safe in this regard and may be used to treat ventilator-associated pneumonia.




HIV-1 drug resistance mutations emerging on darunavir therapy in PI-naive and -experienced patients in the UK

2016-11-16T00:26:23-08:00

Background

Darunavir is considered to have a high genetic barrier to resistance. Most darunavir-associated drug resistance mutations (DRMs) have been identified through correlation of baseline genotype with virological response in clinical trials. However, there is little information on DRMs that are directly selected by darunavir in clinical settings.

Objectives

We examined darunavir DRMs emerging in clinical practice in the UK.

Patients and methods

Baseline and post-exposure protease genotypes were compared for individuals in the UK Collaborative HIV Cohort Study who had received darunavir; analyses were stratified for PI history. A selection analysis was used to compare the evolution of subtype B proteases in darunavir recipients and matched PI-naive controls.

Results

Of 6918 people who had received darunavir, 386 had resistance tests pre- and post-exposure. Overall, 2.8% (11/386) of these participants developed emergent darunavir DRMs. The prevalence of baseline DRMs was 1.0% (2/198) among PI-naive participants and 13.8% (26/188) among PI-experienced participants. Emergent DRMs developed in 2.0% of the PI-naive group (4 mutations) and 3.7% of the PI-experienced group (12 mutations). Codon 77 was positively selected in the PI-naive darunavir cases, but not in the control group.

Conclusions

Our findings suggest that although emergent darunavir resistance is rare, it may be more common among PI-experienced patients than those who are PI-naive. Further investigation is required to explore whether codon 77 is a novel site involved in darunavir susceptibility.




Characterization of NS5A polymorphisms and their impact on response rates in patients with HCV genotype 2 treated with daclatasvir-based regimens

2016-11-16T00:26:23-08:00

Objective

Daclatasvir (DCV) is a pan-genotypic non-structural protein 5A (NS5A) inhibitor that is approved for treatment of hepatitis C virus (HCV) genotype (GT)1 and GT3 in the USA and GT1, GT3 and GT4 in Europe. We set out to examine the impact of daclatasvir-based regimens on the sustained virologic response (SVR) in patients with GT2 infection with respect to GT2 subtype and NS5A polymorphisms at amino acid positions associated with daclatasvir resistance.

Methods

Analyses were performed on 283 GT2 NS5A sequences from five daclatasvir regimen-based clinical trials (ClinicalTrials.gov: NCT-01257204, NCT-01359644, NCT-02032875, NCT-02032888 and NCT-01616524) and 143 NS5A sequences from the Los Alamos HCV database. Susceptibility analyses of substitutions at amino acid positions associated with daclatasvir resistance and patient-derived NS5A sequences were performed using an in vitro HCV replication assay.

Results

Of 13 GT2 subtypes identified from 426 NS5A sequences, the most prevalent were GT2a (32%), GT2b (48%) and GT2c (10%). The most prevalent NS5A polymorphism was L31M (GT2a = 88%; GT2b = 59%; GT2c = 10%). Substitutions identified in 96% of GT2 NS5A sequences exhibited daclatasvir EC50 values ranging from 0.005 to 20 nM when tested in vitro. A similar range in daclatasvir EC50 values was observed for 16 diverse GT2 patient-derived NS5A sequences (EC50 = 0.005–60 nM). Depending on the daclatasvir-based regimen studied (daclatasvir/interferon-based or daclatasvir/sofosbuvir-based), SVR rates ranged from 90% to 100% in GT2 patients with the most prevalent baseline NS5A-L31M polymorphism, compared with from 96% to 100% without this polymorphism.

Conclusions

High SVR rates were achieved in patients infected with GT2 treated with daclatasvir-based regimens irrespective of GT2 subtype or baseline NS5A polymorphisms.




Abacavir has no prothrombotic effect on platelets in vitro

2016-11-16T00:26:23-08:00

Objectives

HIV patients exposed to abacavir have an increased risk of myocardial infarction, with contradictory results in the literature. The aim of our study was to determine whether abacavir has a direct effect on platelet activation and aggregation using platelets from healthy donors and from HIV-infected patients under therapy with an undetectable viral load.

Methods

Platelet-rich plasma (PRP) or whole blood from healthy donors was treated with abacavir (5 or 10 μg/mL) or its active metabolite carbovir diphosphate. Experiments were also performed using blood of HIV-infected patients (n = 10) with an undetectable viral load. Platelet aggregation was performed on PRP by turbidimetry and under high shear conditions at 4000 s–1. Platelet procoagulant potential was analysed by measuring thrombin generation by thrombinography.

Results

Abacavir and carbovir diphosphate significantly increased the aggregation of platelets from healthy donors induced by collagen at 2 μg/mL (P = 0.002), but not at 0.5 μg/mL. No effect of abacavir or carbovir diphosphate was observed on platelet aggregation induced by other physiological agonists or by high shear stress, or on thrombin generation. Pretreatment of blood from HIV-infected patients with abacavir produced similar results.

Conclusions

Our results suggest that abacavir does not significantly influence platelet activation in vitro when incubated with platelets from healthy donors or from HIV-infected patients. It is, however, not excluded that a synergistic effect with other drugs could promote platelet activation and thereby play a role in the pathogenesis of myocardial infarction.




Effectiveness and safety of an abacavir/lamivudine + rilpivirine regimen for the treatment of HIV-1 infection in naive patients

2016-11-16T00:26:23-08:00

Objectives

To describe the effectiveness and safety of an abacavir/lamivudine + rilpivirine regimen in naive HIV-1-infected patients, as there is a lack of data with this combination.

Methods

This was an observational, retrospective, multicentre study in eight Spanish hospitals. All antiretroviral-naive patients ≥18 years old and starting abacavir/lamivudine + rilpivirine were included. Effectiveness (ITT and on-treatment) and safety (adverse events and laboratory parameters) were assessed during follow-up. Values are expressed as n (%) or median (IQR). The Wilcoxon signed-rank test was used to compare baseline and 6 and 12 month values.

Results

Eighty-four patients were included [93% males, age = 36 (30–45) years]. Time since HIV diagnosis was 12 (4–35) months. Fifty-one per cent of patients had comorbidities. Baseline CD4+ was 425 (340–519) cells/mm3 and baseline HIV-RNA was 19 000 (9500–42 000) copies/mL. Median follow-up was 18 (9–22) months; 100% and 68% patients with at least 6 and 12 months, respectively. At 6 and 12 months effectiveness was 94% and 86% by ITT analysis and 96% and 97% by on-treatment analysis. At 12 months, there were significant increases in CD4+ (+262 cell/mm3) and HDL cholesterol (+4 mg/dL) and a significant decrease in the total cholesterol/HDL cholesterol ratio (–0.2). There were two (2.4%) virological failures (HIV-RNA 50–100 copies/mL); one patient later achieving virological suppression without changing the treatment. Six patients (7.1%) changed treatment due to reasons other than virological failure or side effects. One patient discontinued treatment due to gastrointestinal complaints attributed to abacavir/lamivudine.

Conclusions

Abacavir/lamivudine + rilpivirine was an effective and safe option in a selected group of HIV-1-infected treatment-naive patients.




Prediction of hard cardiovascular events in HIV patients

2016-11-16T00:26:23-08:00

Objectives

To assess the accuracy of risk prediction algorithms used in the general population and an HIV-specific algorithm to predict hard cardiovascular events.

Methods

We compared the pooled equation algorithm (PE) proposed by the American Heart Association with the Framingham risk score (FRS) and the HIV-specific DAD (Data Collection on Adverse Effects of Anti-HIV Drugs) algorithm in a cohort of 2550 HIV+ patients followed for 17 337 patient-years.

Results

During follow-up we recorded 67 myocardial infarctions and 2 cardiovascular deaths. PE and FRS identified and missed the same number of events (44 of 69 identified by PE and 49 of 69 by FRS). Similarly, DAD and FRS predicted and missed the same number of events (38 of 64 and 44 of 64 identified, respectively). All algorithms showed moderate sensitivity, specificity and positive predictive values, but high negative predictive values. However, PE and DAD identified more patients with no events than FRS (13.8% and 9.3% net reclassification improvement, respectively).

Conclusions

All algorithms showed a modest predictive ability, although the PE and DAD algorithms identified more patients at low risk.




Low-level viraemia, measured as viraemia copy-years, as a prognostic factor for medium-long-term all-cause mortality: a MASTER cohort study

2016-11-16T00:26:23-08:00

Objectives

We investigated the association between persistent low-level viraemia, measured as viraemia copy-years (VCY), and all-cause mortality.

Methods

We included 3271 HIV-infected patients who initiated their first combined ART (cART) during 1998–2012 enrolled in the multicentre Italian MASTER cohort. VCY was defined as the area under the curve of plasma viral load (pVL) and expressed in log10 copies · years/mL. VCY was evaluated from cART initiation until the end of follow-up [VCY-overall (VCY-o)], and stratified into before [VCY-early (VCY-e)] and after [VCY-late (VCY-l)] the eighth month from starting cART, and as the ratio of VCY-l to follow-up duration (VCY-l/FUD).

Results

The risk of death increased of about 40% for higher than the median levels of VCY-o and VCY-e. Compared with subjects with permanently suppressed pVL after the eighth month from starting cART, mortality increased by 70% for those with VCY-l ≥3 log10 copies·years/mL, and by about 20-fold for those with VCY-l/FUD ≥2.3 log10 copies/mL. Patients who maintained low levels of VCY-l (<3 log10 copies · years/mL) or VCY-l/FUD (<2.3 log10 copies/mL) had a risk of death similar to patients with permanently suppressed pVL. CD4 cell count at baseline was predictive of high risk of death only in subjects with VCY-l ≥3 log10 copies · years/mL.

Conclusions

The risk of death did not increase in HIV-infected patients with low levels of VCY-l compared with patients with permanent virological suppression.




PCR-based detection of Aspergillus fumigatus Cyp51A mutations on bronchoalveolar lavage: a multicentre validation of the AsperGenius assay(R) in 201 patients with haematological disease suspected for invasive aspergillosis

2016-11-16T00:26:23-08:00

Objectives

In patients with invasive aspergillosis (IA), fungal cultures are mostly negative. Consequently, azole resistance often remains undetected. The AsperGenius® multiplex real-time PCR assay identifies clinically relevant Aspergillus species and four resistance-associated mutations (RAMs; TR34/L98H/T289A/Y121F) in the Cyp51A gene. This multicentre study evaluated the diagnostic performance of this assay on bronchoalveolar lavage (BAL) fluid and correlated the presence of RAMs with azole treatment failure and mortality.

Methods

Stored BAL samples from patients with haematological diseases with suspected IA were used. BAL samples that were galactomannan/culture positive were considered positive controls for the presence of Aspergillus. Azole treatment failure and 6 week mortality were compared in patients with and without RAMs that had received ≥5 days of voriconazole monotherapy.

Results

Two hundred and one patients each contributed one BAL sample, of which 88 were positive controls and 113 were negative controls. The optimal cycle threshold cut-off value for the Aspergillus species PCR was <38. With this cut-off, the PCR was positive in 74/88 positive controls. The sensitivity, specificity, positive predictive value and negative predictive value were 84%, 80%, 76% and 87%, respectively. 32/74 BAL samples were culture negative. Azole treatment failure was observed in 6/8 patients with a RAM compared with 12/45 patients without RAMs (P = 0.01). Six week mortality was 2.7 times higher in patients with RAMs (50.0% versus 18.6%; P = 0.07).

Conclusions

The AsperGenius® assay had a good diagnostic performance on BAL and differentiated WT from Aspergillus fumigatus with RAMs, including in culture-negative BAL samples. Most importantly, detection of RAMs was associated with azole treatment failure.




Comparative effectiveness of echinocandins versus fluconazole therapy for the treatment of adult candidaemia due to Candida parapsilosis: a retrospective observational cohort study of the Mycoses Study Group (MSG-12)

2016-11-16T00:26:23-08:00

Objectives

A polymorphism in the gene encoding β-1,3-glucan synthase, the target of the echinocandin class of antifungals, results in increased in vitro MICs of the echinocandins. This has resulted in controversy surrounding use of the echinocandins for treatment of Candida parapsilosis candidaemia. We aimed to compare 30 day mortality in adults with C. parapsilosis candidaemia treated with echinocandins versus fluconazole.

Methods

This is a retrospective observational cohort study. We used the Premier Perspective Database to identify adult patients with C. parapsilosis candidaemia treated with only fluconazole or only an echinocandin as definitive therapy. The primary outcome was 30 day mortality. Propensity scores were derived to estimate the probability the patient would have received either an echinocandin or fluconazole. Inverse probability of treatment weighting (IPTW) was used in a weighted logistic regression to calculate odds of 30 day mortality.

Results

There were 307 unique patients with C. parapsilosis candidaemia. One hundred and twenty-six (41%) received fluconazole and 181 (59%) received an echinocandin. Age, gender, race, year of admission, need for ICU resources in the week prior to candidaemia onset, and receipt of vasopressors on the day of candidaemia onset were included in the propensity score model used to calculate inverse probability of treatment weights. Weighted logistic regression demonstrated no difference in 30 day mortality between patients receiving an echinocandin as compared with fluconazole (OR 0.82, 95% CI 0.33–2.07).

Conclusions

Our result supports the 2016 IDSA invasive candidiasis guidelines, which no longer clearly favour treatment with fluconazole over an echinocandin for C. parapsilosis candidaemia.




Safety, clinical effectiveness and trough plasma concentrations of intravenous posaconazole in patients with haematological malignancies and/or undergoing allogeneic haematopoietic stem cell transplantation: off-trial experience

2016-11-16T00:26:23-08:00

Objectives

This study describes the safety, clinical effectiveness and trough plasma concentration (Cmin) of intravenous (iv) posaconazole, provided as part of Merck Sharp and Dohme Australia's Named Patient Programme (NPP) in non-clinical trial settings.

Methods

A multicentre, retrospective study on the NPP use of iv posaconazole between July 2014 and March 2015 across seven Australian hospitals.

Results

Seventy courses of iv posaconazole were prescribed and evaluated in 61 patients receiving treatment for haematological malignancy. Sixty-one courses were prescribed for prophylaxis against invasive fungal disease (IFD), the majority of which (59) were initiated in patients with gastrointestinal disturbances and/or intolerance to previous antifungals. The median (IQR) duration for prophylaxis was 10 (6–15) days. No breakthrough IFD was observed during or at cessation of iv posaconazole. Nine courses of iv posaconazole were prescribed for treatment of IFD with a median (IQR) duration of 19 (7–30) days. Improvement in signs and symptoms of IFD was observed in five cases at cessation of, and six cases at 30 days post-iv posaconazole. Cmin was measured in 39 courses of iv posaconazole, with the initial level taken [median (IQR)] 4 (3–7) days after commencing iv posaconazole. The median (IQR) of initial Cmin was 1.16 (0.69–2.06) mg/L. No severe adverse events specifically attributed to iv posaconazole were documented, although six courses were curtailed due to potential toxicity.

Conclusions

This non-clinical trial experience suggests that iv posaconazole appeared to be safe and clinically effective for prophylaxis or treatment of IFD in patients receiving treatment for haematological malignancies.




Frequent acquisition of low-virulence strains of ESBL-producing Escherichia coli in travellers

2016-11-16T00:26:23-08:00

Objectives

International travel is a risk factor for intestinal colonization with ESBL-producing Enterobacteriaceae (EPE). This prospective cohort study focuses on molecular features of and risk factors for travel-acquired EPE.

Methods

Rectal swabs and survey data were collected from 188 Swedes travelling to four regions of high EPE prevalence. Samples were plated onto selective agars. ESBL producers were determined using phenotypic methods. Molecular characterization regarding virulence factors and phylogenetic grouping of ESBL-producing Escherichia coli was done using PCR. Isolates were also screened for the plasmid-mediated colistin resistance gene mcr-1.

Results

Among 175 pre-travel EPE-negative participants, 32% were positive upon return. No carbapenemase-producing Enterobacteriaceae were found, but one CTX-M-producing E. coli harboured mcr-1 (travel to Thailand). Most E. coli strains (43.1%) belonged to phylogroup A and were rarely associated with extraintestinal infections and a few (9.2%) expressed uropathogenicity pap genes. During 10–26 months of follow-up, no clinical infections were observed. Colonization rates varied by visited region: the Indian subcontinent, 49.2%; northern Africa, 44.0%; South-East Asia, 19.1%; and Turkey, 9.5%. Travellers' diarrhoea (OR 2.5, P = 0.04) or antimicrobial treatment during the trip (OR 5.9, P = 0.02) were both independent risk factors for EPE colonization.

Conclusions

EPE acquired during travel have seemingly low pathogenicity, possibly indicating a low risk of clinical infection. Pre-travel advice should emphasize avoiding unnecessary antibiotic treatment during travel.




Universal hospital admission screening for carbapenemase-producing organisms in a low-prevalence setting

2016-11-16T00:26:23-08:00

Background

Carbapenemase-producing Enterobacteriaceae (CPE) are an emerging threat for healthcare providers worldwide.

Objectives

To determine CPE carriage rates and risk factors in an unselected hospital cohort at the time of admission.

Methods

We approached 4567 patients within 72 h of admission to provide a rectal swab and answer a questionnaire on risk factors for carriage. Rectal swabs were cultured for carbapenem-resistant organisms on chromogenic and non-chromogenic agar, and tested for carbapenemase production by PCR (Check-Direct CPE). The study was approved by the NHS Research Ethics Committee.

Results

Only 6 CPE were cultured from 5 (0.1%) of 4006 patients who provided a rectal swab; only 1 was cultured using non-chromogenic media. An additional 76 culture-negative rectal swabs were initially PCR positive, but none grew a carbapenem-resistant organism despite enrichment culture and only two were positive when retested several months later by Check-Direct and a second PCR assay (Cepheid GeneXpert® Carba-R). A modified Ct cut-off of <35 would have resolved these apparent false-positives. 40% of patients had a risk factor that should prompt screening and pre-emptive isolation as defined by UK CPE guidelines but only 8.1% and 20.2% of these patients had been screened and pre-emptively isolated by clinical teams, respectively. Overseas hospitalization was the only significant risk factor for CPE carriage (P < 0.001, OR 64.3, 95% CI 7.3–488.5).

Conclusions

This study highlights a very low carriage rate of CPE. Hospitalization abroad is the most important risk factor to guide admission screening in this low-prevalence setting.




Escherichia coli antimicrobial susceptibility profile and cumulative antibiogram to guide empirical treatment of uncomplicated urinary tract infections in women in the province of Quebec, 2010-15

2016-11-16T00:26:23-08:00

Objectives Empirical treatment of uncomplicated urinary tract infections (UTIs) in women should be based on local susceptibility data. We aimed to generate regional and provincial cumulative antibiograms combining data from different laboratory information systems and determine the impact of basic patient characteristics on susceptibility results. Methods All positive urine samples for Escherichia coli obtained from women aged 18–65 years old in outpatient settings between 1 April 2010 and 31 March 2015 from four hospitals in Quebec, Canada, were included. The cumulative antibiogram for ciprofloxacin, nitrofurantoin and trimethoprim/sulfamethoxazole was calculated. A clinically significant difference in susceptibility profile was defined as factor(s) that lowered the susceptibility proportion below 80%. Results A total of 36 293 positive urine cultures were analysed. In the last year of the study, the proportion of susceptibility for ciprofloxacin, nitrofurantoin and trimethoprim/sulfamethoxazole was 90.3%, 95.4% and 81.9%, respectively. The susceptibility proportion was <80% for trimethoprim/sulfamethoxazole in the Montreal region (73.4%; 95% CI 71.1%–75.9%), whereas it remained >80% for the other regions. A significant decrease in susceptibility with time was identified for ciprofloxacin (92.1%–90.3%, P < 0.001) and nitrofurantoin (97.1%–95.4%, P < 0.001). Increasing age, recent hospitalization and site of collection were associated with an increase in resistance for certain antibiotics. Conclusions Overall, all first-line antimicrobials remain acceptable choices for empirical treatment of uncomplicated UTIs in women in Quebec. The regional variability in susceptibility data within a single province emphasizes the importance of local susceptibility data to inform the development of empirical treatment guidelines for UTIs. [...]



Outpatient use of ceftaroline fosamil versus vancomycin for osteoarticular infection: a matched cohort study

2016-11-16T00:26:23-08:00

Objectives There are few convenient intravenous options for long-term outpatient treatment of osteoarticular infection (OAI) and limited effectiveness and safety data exist for this off-label use of ceftaroline. The objective of this study was to describe the long-term effectiveness and safety of ceftaroline for the treatment of OAI. Methods This was a matched retrospective cohort study of patients receiving ceftaroline- or vancomycin-based therapy for OAI in the outpatient setting. Patients were matched according to infection subtype, anatomical site and microbiology. The primary endpoint was 180 day infection-related readmission (IRR). Secondary endpoints included all-cause readmission, time-to-IRR and adverse event incidence. Results The final matched cohort consisted of 50 ceftaroline-treated patients and 50 vancomycin-treated patients. The IRR incidence was 22% for ceftaroline patients and 30% for vancomycin patients; OR = 0.66 (95% CI = 0.27–1.62; P = 0.362). There was no significant difference between groups in all-cause readmission or time-to-IRR. Attributable adverse event incidences were 24% and 18% for ceftaroline and vancomycin, respectively. Rash (10%) and nausea (6%) were the most common ceftaroline adverse events, while acute kidney injury (6%) and rash (4%) were the most common vancomycin adverse events. Conclusions Attributable readmission and adverse events were common among patients treated with outpatient intravenous antimicrobials for OAI. This study found no appreciable difference in effectiveness or tolerability between ceftaroline- or vancomycin-treated patients. Although further research will be important to delineate the role of ceftaroline in the management of OAI, data derived from this study may aid clinicians in determining therapy when limited options exist. [...]



A Phase III, randomized, controlled, non-inferiority trial of ceftaroline fosamil 600 mg every 8 h versus vancomycin plus aztreonam in patients with complicated skin and soft tissue infection with systemic inflammatory response or underlying comorbidities

2016-11-16T00:26:23-08:00

Objectives Increasing the ceftaroline fosamil dose beyond 600 mg every 12 h may provide additional benefit for patients with complicated skin and soft tissue infections (cSSTIs) with severe inflammation and/or reduced pathogen susceptibility. A Phase III multicentre, randomized trial evaluated the safety and efficacy of ceftaroline fosamil 600 mg every 8 h in this setting. Methods Adult patients with cSSTI and systemic inflammation or comorbidities were randomized 2:1 to intravenous ceftaroline fosamil (600 mg every 8 h) or vancomycin (15 mg/kg every 12 h) plus aztreonam (1 g every 8 h) for 5–14 days. Clinical cure was assessed at the test of cure (TOC) visit (8–15 days after the final dose) in the modified ITT (MITT) and clinically evaluable (CE) populations. Non-inferiority was defined as a lower limit of the 95% CI around the treatment difference greater than –10%. An MRSA-focused expansion period was initiated after completion of the main study. Clinicaltrials.gov registration numbers NCT01499277 and NCT02202135. Results Clinical cure rates at TOC demonstrated non-inferiority of ceftaroline fosamil 600 mg every 8 h versus vancomycin plus aztreonam in the MITT and CE populations: 396/506 (78.3%) versus 202/255 (79.2%) patients (difference –1.0%, 95% CI –6.9, 5.4) and 342/395 (86.6%) versus 180/211 (85.3%) patients (difference 1.3%, 95% CI –4.3, 7.5), respectively. In the expansion period, 3/4 (75%) patients treated with ceftaroline fosamil were cured at TOC. The frequency of adverse events was similar between groups. Conclusions Ceftaroline fosamil 600 mg every 8 h was effective for cSSTI patients with evidence of systemic inflammation and/or comorbidities. No new safety signals were identified. [...]



Predicting the risk of nephrotoxicity in patients receiving colistimethate sodium: a multicentre, retrospective, cohort study

2016-11-16T00:26:23-08:00

Objectives With increasing rates of infections caused by MDR Gram-negative organisms, clinicians resort to older agents such as colistimethate sodium (CMS) despite a significant risk of nephrotoxicity. Several risk factors for CMS-associated nephrotoxicity have been reported, but they have yet to be validated. We compared the performance of published mathematical models in predicting the risk of CMS-associated nephrotoxicity. Methods In a multicentre, retrospective, cohort study, adult patients (≥18 years of age) were evaluated from five large academic medical centres in the USA. Patients with normal renal function (baseline serum creatinine ≤1.5 mg/dL) who received intravenous CMS for ≥72 h were followed for up to 30 days. The development of nephrotoxicity was as defined by the RIFLE criteria. Each published model was conditioned using patient-specific variables to predict the risk of nephrotoxicity. The predictive performance of the models was evaluated using the observed-to-expected (O/E) ratio. The most significant cut-off threshold for stratifying patients into high and low risk of nephrotoxicity was identified using classification and regression tree analysis. Results A total of 106 patients were examined (mean age 53.3 ± 14.9 years, 66% male); the overall observed nephrotoxicity rate was 52.8%. We identified a simple model demonstrating reasonable overall nephrotoxicity risk assessment [O/E ratio of 1.07 (95% CI = 0.81–1.39)] and high sensitivity (92.9%) in predicting nephrotoxicity development in patients on CMS therapy. Conclusions We identified a model that could be incorporated into patient management strategies to reduce the risk of nephrotoxicity in patients requiring CMS therapy. [...]



Information provision for antibacterial dosing in the obese patient: a sizeable absence?

2016-11-16T00:26:23-08:00

Background Obesity is on course to overtake being underweight as a global disease burden. Obesity alters antibacterial pharmacokinetics (PK) and pharmacodynamics (PD). Historically, drug PK/PD parameters have not been studied in obese populations. This means dose recommendations risk being sub-therapeutic in a population at increased risk of infection. Suboptimal antibacterial prescribing is widely associated with treatment failure, worse clinical outcomes, unnecessary escalation to broad-spectrum therapy and the emergence of antimicrobial resistance (AMR). Objectives To analyse current information provided by pharmaceutical companies, for the most commonly prescribed antibacterial agents in the UK, for evidence of dosing guidance for obese adults. Methods We analysed the manufacturers' Summary of Product Characteristics (SPC) for 42 of the most clinically important and frequently prescribed antibacterial agents dispensed across both primary and secondary care. The manufacturer's SPC was reviewed, and cross-referenced with the online British National Formulary, to assess dosing guidance for obese adults. Results No advice was provided to guide dosing for obese adults in 35 (83%) of 42 of the most clinically important and frequently prescribed antibacterial agents in the UK. Seven (17%) antibacterial agents (tigecycline, vancomycin, daptomycin, amikacin, gentamicin, tobramycin and teicoplanin) provided variable levels of advice. Conclusions There is a paucity of advice and evidence in the UK to guide dosing common antibacterial agents in the obese. The literature on antibacterial PK/PD studies in obese populations remains scarce. In the face of the increasing risks of AMR combined with the global rise of obesity there is an urgent need to address this significant rese[...]



Trends, demographics and disparities in outpatient antibiotic consumption in New Zealand: a national study

2016-11-16T00:26:23-08:00

Objectives

Knowledge of the patterns of antibiotic consumption within a population provides valuable information on when, where and to whom antibiotics are prescribed. Such knowledge is critical in informing possible public health interventions to reduce inappropriate antibiotic use. The aims of this study were to (i) determine national patterns of antibiotic consumption, including assessment of seasonal variation in prescribing, and (ii) explore potential associations between antibiotic consumption and patient characteristics, such as age, sex and ethnicity.

Methods

Data on all subsidized antibiotic dispensing in New Zealand between 1 January 2006 and 31 December 2014 were obtained and stratified according to age, sex and ethnicity. Antibiotic dispensing was expressed as the number of DDDs per 1000 population per day (DID).

Results

Total antibiotic consumption in New Zealand increased by 49% from 17.3 DID in 2006 to 25.8 DID in 2014. The increase in antibiotic consumption occurred in all ages and amongst all ethnic groups. The use of extended-spectrum penicillins, which almost doubled in the study period, made a major contribution to the overall increase and was highest in young children and in Pacific peoples. Consumption of quinolones increased early in the study period and then declined from 2011 onwards.

Conclusions

Future work should focus on identifying the appropriateness of antibiotic prescribing, particularly for penicillin prescribing in Pacific peoples and children, and on both reducing unwarranted antibiotic use and improving antibiotic selection when therapy is indicated.




Global access to antifungal therapy and its variable cost

2016-11-16T00:26:23-08:00

Background Antifungal therapy saves lives, if given early in life-threatening invasive infection, and also greatly reduces morbidity in hundreds of millions of patients worldwide. Objectives We have partially mapped by country systemic generic antifungal drug registration, availability and daily cost for intravenous deoxycholate amphotericin B (50 mg), flucytosine (5 g), oral fluconazole (750–800 mg) and oral itraconazole (400 mg). Methods Multiple publically available resources and local country contacts provided data for 159 countries with populations >1 million. Results Amphotericin B is not licensed in and unavailable in 22 of 155 (14.2%) and 42 of 155 (27.1%) countries, respectively, representing an unserved population of 481 million. The daily price of deoxycholate amphotericin B varied from <$1 to $171. Fluconazole was licensed in all 141 (88.6%) countries for which data were available although 2 countries appear wholly dependent on the Diflucan® Partnership Program, which is restricted to HIV/AIDS patients. The daily price of fluconazole varied from <$1 to $31. Itraconazole is not licensed in and unavailable in at least 3 of 123 (2.4%) and 5 of 125 (4.0%) countries, respectively, representing an unserved population of at least 78 million. The daily price of itraconazole varied from <$1 to $102. Flucytosine is not licensed in and is unavailable in 89 of 125 (71.2%) and 95 of 125 (76.0%) countries, respectively, representing an unserved population of 2898 million. The daily price of flucytosine varied from $4.60 to $1409. Conclusions National governments without access to antifungal drugs should address this health system deficiency urgently to improve clinical outcomes from serious fu[...]



Quantitative assessment of antimicrobial resistance in livestock during the course of a nationwide antimicrobial use reduction in the Netherlands

2016-11-16T00:26:23-08:00

Objectives To quantify associations between antimicrobial use and acquired resistance in indicator Escherichia coli over a period of time which involved sector-wide antimicrobial use reductions in broilers and pigs (years 2004–14), veal calves (2007–14) and dairy cattle (2005–14). Prevalence estimates of resistance were predicted for a hypothetical further decrease in antimicrobial use. Methods Data reported annually for the resistance surveillance programme in the Netherlands were retrieved. Two multivariate random-effects logistic models per animal sector were used to relate total and class-specific antimicrobial use (as defined daily dosages per animal per year, DDDA/Y) with the probability of E. coli resistance to a panel of 10 antimicrobial agents. Results Positive dose–response relationships (ORs) were obtained from all models. Specific resistance phenotypes were more often associated with total antimicrobial use than with class-specific use. The most robust associations were found in pigs and veal calves. Resistance to historically widely used antimicrobials (e.g. penicillins, tetracyclines) was, in relative terms, less influenced by drug use changes over time than resistance to newer or less prescribed antimicrobials (e.g. third-/fourth-generation cephalosporins, fluoroquinolones). In pigs and veal calves, prevalence estimates for the most common resistance phenotypes were projected to decline ~5%–25% during 2014–16 if total antimicrobial use reduction reached 80%; projections for poultry and dairy cows were more modest. Conclusions Epidemiological evidence indicated that drug use history and co-selection of resistance are key elements for perp[...]



























Acknowledgement to Referees 2016

2016-11-16T00:26:24-08:00




Contribution of JAC to antimicrobial stewardship

2016-10-21T00:01:08-07:00

Antimicrobial stewardship programmes are increasingly being used to improve the quality of antimicrobial prescribing, with the dual aim of optimizing clinical outcomes and minimizing the emergence and spread of antimicrobial resistance. The Journal of Antimicrobial Chemotherapy (JAC) is celebrating its 40th anniversary and, as part of activities to commemorate this event, this article highlights the contribution of JAC to antimicrobial stewardship. Papers published in JAC have contributed to the evidence base for stewardship, have highlighted educational and behavioural change initiatives aimed at improving antibiotic prescribing practice, and have actively sought to foster the practice of antimicrobial stewardship amongst its readers.




Pharmacodynamics for antifungal drug development: an approach for acceleration, risk minimization and demonstration of causality

2016-10-21T00:01:08-07:00

The treatment of invasive fungal diseases constitutes a significant unmet medical need. There are relatively few antifungal agents in clinical development and a paucity of novel targets. Morbidity and mortality remain high and clinical outcomes are compromised by submaximal efficacy, emergence of drug resistance and drug-related toxicity. Thus, new antifungal agents are urgently required. A deep understanding of exposure–response relationships underpins the development of safe and effective clinical regimens of any therapeutic agent. Pharmacokinetics (PK) and pharmacodynamics (PD) is increasingly recognized as a vital tool in the development of new antimicrobial agents and maximizes the probability that the right dose will be studied the first time. There is currently no information or agreement as to what constitutes an adequate PK/PD package for the development of a new antifungal agent. This review provides a summary of the achievements of antifungal PK/PD for the treatment of invasive candidiasis, invasive aspergillosis and cryptococcal meningoencephalitis, and outlines the necessary components of a PK/PD package for a new antifungal agent. Such information is critical for the accelerated and efficient development of new agents and enables improved clinical outcomes to be secured.




Therapeutic drug monitoring of vancomycin: a guideline of the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society

2016-10-21T00:01:08-07:00

Background Guideline development should be based on the quality of evidence, balance of benefits and harms, economic evaluation and patients’ views and preferences. Therefore, these factors were considered in the development of a new guideline for therapeutic drug monitoring (TDM) of vancomycin. Objectives To develop an evidence-based guideline for vancomycin TDM and to promote standardized vancomycin TDM in clinical practice in China. Methods We referred to the WHO Handbook for Guideline Development and used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to rate the quality of evidence and grade the strength of recommendations, according to economic evaluation and patients’ views and preferences. We used the GRADE Grid method to formulate the recommendations. Results The guideline presents recommendations about who should receive vancomycin TDM, how to monitor vancomycin efficacy and renal safety, therapeutic trough concentrations, time to start initial vancomycin TDM, loading dose and how to administer and adjust the vancomycin dose. Conclusions We developed an evidence-based guideline for vancomycin TDM, which provides recommendations for clinicians and pharmacists to conduct vancomycin TDM in China. [...]