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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)



 



40 years of veterinary papers in JAC - what have we learnt?

2016-09-22T00:05:52-07:00

This review, for the occasion of the 40th anniversary of the Journal of Antimicrobial Chemotherapy (JAC), gives an overview of the manuscripts related to veterinary bacteriology published in the journal in the past 40 years with a focus on ‘One Health’ aspects. From 1975 to 2000 the number of manuscripts related to veterinary medicine was limited, but thereafter, the number steadily increased. Most manuscripts published were related to food-producing animals, but companion animals and minor species were also covered. Subjects included antimicrobial usage in animals and the consequences for human medicine, new resistance genes and mechanisms, the prevalence and epidemiology of antimicrobial resistance, and the emergence of resistant bacteria in animals with zoonotic potential such as livestock-associated MRSA (LA-MRSA), methicillin-resistant Staphylococcus pseudintermedius (MRSP) and ESBL-producing Enterobacteriaceae. These manuscripts have added to our knowledge on the risks of transmission of resistant bacteria from animals to humans and the importance of the prudent use of antimicrobial agents in veterinary medicine.




Pharmacokinetic/pharmacodynamic-based optimization of levofloxacin administration in the treatment of MDR-TB

2016-09-22T00:05:52-07:00

The emergence of MDR-TB and XDR-TB has complicated TB treatment success. Among many factors that contribute to the development of resistance, low drug exposure is not the least important. This review summarizes the available information on pharmacokinetic properties of levofloxacin in relation to microbial susceptibilities, in order to optimize the dose and make general treatment recommendations. A total of 37 studies on adult (32 studies) and paediatric (5 studies) MDR-TB patients were included. Among the 32 adult studies, 19 were on susceptibility of Mycobacterium tuberculosis isolates to levofloxacin by MIC, 1 was on susceptibility of M. tuberculosis isolates to levofloxacin by MBC, 1 was on susceptibility of M. tuberculosis isolates to levofloxacin by mutant prevention concentration and 4 were on pharmacokinetics of levofloxacin, and 7 others were included. Likewise, out of five studies on children, two dealt with levofloxacin pharmacokinetic parameters, one reviewed CSF concentrations and two dealt with background information. In adult MDR-TB patients, standard dosing of once-daily 1000 mg levofloxacin in TB treatment did not consistently attain the target concentration (i.e. fAUC/MIC >100 and fAUC/MBC >100) in 80% of the patients with MIC and MBC of 1 mg/L, leaving them at risk of developing drug resistance. However, with an MIC of 0.5 mg/L, 100% of the patients achieved the target concentration. Similarly, paediatric patients failed consistently in achieving given pharmacokinetic/pharmacodynamic targets due to age-related differences, demanding a shift towards once daily dosing of 15–20 mg/kg. Therefore, we recommend therapeutic drug monitoring for patients with strains having MICs of ≥0.5 mg/L and suggest revising the cut-off value from 2 to 1 mg/L.




A review of the pharmacokinetics and pharmacodynamics of aztreonam

2016-09-22T00:05:52-07:00

The monobactam aztreonam is currently being re-examined as a therapeutic agent in light of the global spread of carbapenem resistance in aerobic Gram-negative bacilli and aztreonam's stability to Ambler class B metallo-β-lactamases. Of particular interest are the pharmacokinetic and pharmacodynamic properties of aztreonam alone and in combination with β-lactamase inhibitors. The choice of inhibitor may vary depending on the spectrum of β-lactamases produced by Enterobacteriaceae. The monobactam ring is also being used to produce new developmental monobactams. Thus, a greater understanding of aztreonam pharmacokinetics and dynamics is of great relevance in drug development. This review summarizes the pharmacokinetic profile of aztreonam in man and its pharmacodynamics in human and pre-clinical studies when studied alone and with β-lactamase inhibitors.




Spotlight on ceftazidime/avibactam: a new option for MDR Gram-negative infections

2016-09-22T00:05:52-07:00

During the last decade infections caused by MDR Gram-negative bacteria (GNB) have become increasingly prevalent. Because of their high morbidity and mortality rates, these infections constitute a serious threat to public health worldwide. Ceftazidime/avibactam is a new approved agent combining ceftazidime and a novel β-lactamase inhibitor with activity against various β-lactamases produced by MDR GNB. Avibactam has a spectrum of inhibition of class A and C β-lactamases, including ESBLs, AmpC and Klebsiella pneumoniae carbapenemase (KPC) enzymes. Thus, combination with this inhibitor expands ceftazidime's spectrum of activity to MDR Enterobacteriaceae and Pseudomonas aeruginosa strains. In Phase II clinical trials of patients with complicated intra-abdominal infections and complicated urinary tract infections ceftazidime/avibactam exhibited clinical efficacy comparable to those of meropenem and imipenem/cilastatin, respectively. A Phase III clinical trial confirmed the efficacy of ceftazidime/avibactam in patients with MDR Enterobacteriaceae and P. aeruginosa infections. Microbiological surveillance studies, in vivo animal models of infection and pharmacokinetic/pharmacodynamic target attainment analyses are also discussed, to assess the potential role of this new drug in the treatment of infections caused by MDR GNB.




Antimicrobial resistance surveillance in urinary tract infections in primary care

2016-09-22T00:05:52-07:00

Urinary tract infection (UTI) is one of the most common reasons for prescription of antimicrobials in primary care. Laboratory resistance data produced because of specimen analysis to support individual patient diagnosis and management are generalized to guide empirical therapy across a wider population, but are limited by bias toward certain patient groups and almost certainly overestimate the incidence of resistance. Other methods of surveillance are required to provide unbiased estimates of antimicrobial resistance, but need to be sustainable. Sentinel surveillance, perineal flora sampling and development of clinical algorithms to support more stratified and personalized antimicrobial prescribing need to be further investigated. Linkages to prescription and clinical outcome data are essential if the burden of antimicrobial resistance in UTI is to be understood. Pilot and feasibility studies need to be performed to establish the best approach to enhancing the quality, relevance and sustainability of antimicrobial resistance surveillance in community-acquired UTI.




Natural history and decolonization strategies for ESBL/carbapenem-resistant Enterobacteriaceae carriage: systematic review and meta-analysis

2016-09-22T00:05:52-07:00

Background

ESBL-producing Enterobacteriaceae and carbapenem-resistant Enterobacteriaceae (CRE) are rapidly spreading worldwide. Their natural reservoir is intestinal.

Methods

We carried out a systematic review and meta-analysis to estimate CRE and ESBL carriage duration and to evaluate the effect of decolonization therapy. We included cohort and comparative studies examining the natural history of CRE/ESBL colonization, examining rates of carriage following decolonization or comparing decolonization and no decolonization conducted in the healthcare setting or in the community. A comprehensive search was conducted until November 2015. We compiled carriage rates at 1, 3, 6 and 12 months with and without decolonization therapy and assessed the effect of decolonization.

Results

Thirty-seven studies fulfilled inclusion criteria. In healthcare settings, pooled ESBL/CRE colonization rates decreased without intervention from 76.7% (95% CI = 69.3%–82.8%) at 1 month to 35.2% (95% CI = 28.2%–42.9%) at 12 months of follow-up. Following decolonization, the rate was 37.1% (95% CI = 27.5%–47.7%) at end of therapy and 57.9% (95% CI = 43.1%–71.4%) at 1 month. In two randomized trials, carriage was significantly reduced at end of therapy (risk ratio = 0.42, 95% CI = 0.25–0.65), but the effect was not significant after 1 month (risk ratio = 0.72, 95% CI = 0.48–1.05), with no longer follow-up. Heterogeneity was explained by surveillance methodology, with no differences observed between ESBLs and CREs. Among community dwellers, ESBL colonization decreased from 52.3% (95% CI = 29.5%–74.2%) at 1 month to 19.2% (95% CI = 9.7%–34.4%) at 6 months.

Conclusions

A significant proportion of ESBL and CRE carriers remain colonized up to 1 year in the healthcare setting. While short-term decolonization therapy reduces carriage during therapy, its longer-term effects are unclear.




Systematic review and meta-analysis: triple therapy combining a proton-pump inhibitor, amoxicillin and metronidazole for Helicobacter pylori first-line treatment

2016-09-22T00:05:52-07:00

Background

Due to clarithromycin resistance, the current efficacy of Helicobacter pylori first-line triple therapies including clarithromycin is low. It seems reasonable to explore alternative clarithromycin-free therapies.

Objectives

The objective of this study was to evaluate the efficacy of triple therapy including a proton-pump inhibitor (PPI), amoxicillin and metronidazole (PAM) as first-line H. pylori therapy by systematic review and meta-analysis.

Methods

Studies evaluating PAM in adult patients were included. Meta-analyses comparing PAM with other treatments were performed. The primary endpoint was the ITT eradication rate for H. pylori first-line treatment. In addition, sensitivity analyses ascertained the effects of treatment schedule, dosage and duration on cure rates.

Results

Ninety-four studies (8061 patients) were included. Meta-analyses comparing PAM versus clarithromycin-including triple therapies showed a significant difference in favour of PPI, amoxicillin and clarithromycin (PAC) (70% versus 77.1%; OR = 0.70, 95% CI = 0.56–0.88) and PPI, metronidazole and clarithromycin (PMC) therapy (66.4% versus 77.7%; OR = 0.55, 95% CI = 0.39–0.76). Sensitivity analyses showed a similar efficacy of PAM versus PAC when drugs were administered for 14 days (80% versus 84%; OR = 0.70, 95% CI = 0.44–1.12). There were not enough studies to perform further comparisons. Number of antibiotic doses (P = 0.012), length of treatment (P < 0.001) and use of high metronidazole doses (P = 0.021) were related to higher cure rates in the sensitivity analysis including observational studies.

Conclusions

PAM was less efficacious than clarithromycin-including triple therapies. However, its efficacy was similar to that of PAC when drugs were administered for 14 days, although ITT cure rates did not reach 90%. Use of 14 day, thrice daily and high-metronidazole-dose PAM treatments markedly increased the cure rate.




Amikacin use and therapeutic drug monitoring in adults: do dose regimens and drug exposures affect either outcome or adverse events? A systematic review

2016-09-22T00:05:52-07:00

Objectives

The objectives of this study were to identify the amikacin dosage regimens and drug concentrations consistent with good outcomes and to determine the drug exposures related to nephrotoxicity and ototoxicity.

Methods

A literature review was conducted in Medline, EMBASE and the Cochrane Central Register of Controlled Trials. Full journal articles reporting randomized controlled trials, controlled clinical trials, interrupted time series trials, and controlled before and after studies involving amikacin therapeutic drug monitoring (TDM) and dose adjustment were considered for inclusion.

Results

Seventeen studies for inclusion were identified, comprising 1677 participants. Amikacin doses ranged from 11 to 15 mg/kg/day with 13 studies using 15 mg/kg/day. Studies were generally designed to compare different aminoglycosides rather than to assess concentration–effect relationships. Only 11 papers presented data on target concentrations, rate of clinical cure and toxicity. Target peak concentrations ranged from 15 to 40 mg/L and target troughs were typically <10 or <5 mg/L. It was not clear whether these targets were achieved. Measured peaks averaged 28 mg/L for twice-daily dosing and 40–45 mg/L for once-daily dosing; troughs averaged 5 and 1-2 mg/L, respectively. Fifteen of the included studies reported rates of nephrotoxicity; auditory and vestibular toxicities were reported in 12 and 8 studies.

Conclusions

This systematic review found little published evidence to support an optimal dosage regimen or TDM targets for amikacin therapy. The use of alternative approaches, such as consensus opinion and a review of current practice, will be required to develop guidelines to maximize therapeutic outcomes and minimize toxicity with amikacin.




Rilpivirine resistance mutation E138K in HIV-1 reverse transcriptase predisposed by prevalent polymorphic mutations

2016-09-22T00:05:52-07:00

Background

Rilpivirine is listed as a recommended or alternative key drug in the current ART guidelines. E138K in HIV-1 reverse transcriptase (RT) is a primary mutation in resistance to rilpivirine, although in vitro experiments showed it confers only <3-fold resistance. An unidentified mechanism could amplify resistance to rilpivirine conferred by E138K.

Objectives

The objective of this study was to reveal the mechanism amplifying rilpivirine resistance conferred by E138K.

Patients and methods

HIV-1 RT sequences were compared in patients who failed rilpivirine-containing ART virologically. The effects of mutations commonly identified with E138K on rilpivirine susceptibility were analysed by using recombinant HIV-1 variants.

Results

Rilpivirine-containing ART was introduced in 162 HIV-1-infected patients at the outpatient clinic of the AIDS Clinical Center (National Center for Global Health and Medicine, Tokyo, Japan) between May 2012 and June 2015. Virological treatment failure occurred in six of these patients. E138K emerged in three patients while other rilpivirine resistance mutations emerged in the other three patients. I135T/L were identified in only three patients with E138K and existed before the introduction of rilpivirine-containing ART. Analysis of recombinant HIV-1 variants indicated that E138K conferred low-level rilpivirine resistance and that coexistence of I135T/L with E138K amplified the resistance.

Conclusions

I135T/L, escape mutations from HLA-B*51/52-restricted cytotoxic T lymphocytes, which are prevalent in Japan, may predispose HIV-1 to harbour E138K upon failure of rilpivirine-containing ART. The mutation patterns of drug resistance may vary due to baseline polymorphic mutations.




Identification of novel macrolides with antibacterial, anti-inflammatory and type I and III IFN-augmenting activity in airway epithelium

2016-09-22T00:05:52-07:00

Background

Exacerbations of asthma and COPD are triggered by rhinoviruses. Uncontrolled inflammatory pathways, pathogenic bacterial burden and impaired antiviral immunity are thought to be important factors in disease severity and duration. Macrolides including azithromycin are often used to treat the above diseases, but exhibit variable levels of efficacy. Inhaled corticosteroids are also readily used in treatment, but may lack specificity. Ideally, new treatment alternatives should suppress unwanted inflammation, but spare beneficial antiviral immunity.

Methods

In the present study, we screened 225 novel macrolides and tested them for enhanced antiviral activity against rhinovirus, as well as anti-inflammatory activity and activity against Gram-positive and Gram-negative bacteria. Primary bronchial epithelial cells were grown from 10 asthmatic individuals and the effects of macrolides on rhinovirus replication were also examined. Another 30 structurally similar macrolides were also examined.

Results

The oleandomycin derivative Mac5, compared with azithromycin, showed superior induction (up to 5-fold, EC50 = 5–11 μM) of rhinovirus-induced type I IFNβ, type III IFN1 and type III IFN2/3 mRNA and the IFN-stimulated genes viperin and MxA, yet had no effect on IL-6 and IL-8 mRNA. Mac5 also suppressed rhinovirus replication at 48 h, proving antiviral activity. Mac5 showed antibacterial activity against Gram-positive Streptococcus pneumoniae; however, it did not have any antibacterial properties compared with azithromycin when used against Gram-negative Escherichia coli (as a model organism) and also the respiratory pathogens Pseudomonas aeruginosa and non-typeable Haemophilus influenzae. Further non-toxic Mac5 derivatives were identified with various anti-inflammatory, antiviral and antibacterial activities.

Conclusions

The data support the idea that macrolides have antiviral properties through a mechanism that is yet to be ascertained. We also provide evidence that macrolides can be developed with anti-inflammatory, antibacterial and antiviral activity and show surprising versatility depending on the clinical need.




P-glycoprotein (ABCB1) activity decreases raltegravir disposition in primary CD4+P-gphigh cells and correlates with HIV-1 viral load

2016-09-22T00:05:52-07:00

Objectives

To evaluate the role of P-glycoprotein (P-gp) and multidrug-resistant-protein 1 (MRP1) on raltegravir intracellular drug disposition in CD4+ T cells, investigate the effect of HIV-1 infection on P-gp expression and correlate HIV-1 viraemia with P-gp activity in primary CD4+ T cell subsets.

Methods

The cellular accumulation ratio of [3H]raltegravir was quantified in CD4+ T cell lines overexpressing either P-gp (CEM-P-gp) or MRP1 (CEM-MRP1) and in primary CD3+CD4+ T cells with high (P-gphigh) and low P-gp activity (P-gplow); inhibition of efflux transporters was confirmed by the intracellular retention of calcein-AM. The correlation of P-gp activity with HIV-1 viraemia was assessed in naive and memory T cell subsets from 21 HIV-1-infected treatment-naive subjects.

Results

[3H]Raltegravir cellular accumulation ratio decreased in CEM-P-gp cells (P < 0.0001). XR9051 (a P-gp inhibitor) and HIV-1 PIs reversed this phenomenon. Primary CD4+P-gphigh cells accumulated less raltegravir (38.4% ± 9.6%) than P-gplow cells, whereas XR9051 also reversed this effect. In vitro HIV-1 infection of PBMCs and stimulation of CD4+ T cells increased P-gp mRNA and P-gp activity, respectively, while primary CD4+P-gphigh T cells sustained a higher HIV-1 replication than P-gplow cells. A significant correlation between HIV-1 viraemia and P-gp activity was found in different CD4+ T cell subsets, particularly memory CD4+ T cells (r = 0.792, P < 0.0001).

Conclusions

Raltegravir is a substrate of P-gp in CD4+ T cells. Primary CD4+P-gphigh T cells eliminate intracellular raltegravir more readily than P-gplow cells and HIV-1 viraemia correlates with P-gp overall activity. Specific CD4+P-gphigh T cell subsets could facilitate the persistence of viral replication in vivo and ultimately promote the appearance of drug resistance.




Sequential steps of daptomycin resistance in Enterococcus faecium and reversion to hypersusceptibility through IS-mediated inactivation of the liaFSR operon

2016-09-22T00:05:52-07:00

Objectives

To improve understanding of mechanisms of daptomycin resistance and to dissect the genetic basis of reversion to daptomycin hypersusceptibility in Enterococcus faecium.

Methods

Daptomycin-resistant mutants (Mut4, Mut8, Mut16, Mut32, Mut64 and Mut128 with MICs from 4 to 128 mg/L) were obtained in vitro from E. faecium strain Aus0004 (MIC at 2 mg/L). The entire genome sequences of Mut64 and Mut128 were determined as well as those of liaFSR and cls genes for other mutants and corresponding revertants (named Rev4 to Rev128). The study of daptomycin resistance stability was performed without any selective pressure. The expression of liaF, liaS and liaR genes was quantified by quantitative RT–PCR.

Results

By comparative genomic analysis, substitutions Asn13Ser in cls and Gly92Asp in liaS were identified in Mut64 and Mut128. Only the liaS mutation was found in Mut16 and Mut32 while Mut4 and Mut8 were devoid of any mutation. After 15 days, all mutants except Mut4 reverted to daptomycin hypersusceptibility (MICs from 0.12 to 0.25 mg/L). In all revertants (except Rev4 and Rev8), an IS was found in the liaFSR operon with a dramatic decrease of its expression: IS66 in the promoter region of liaF (Rev16 and Rev64), IS30 in liaR (Rev32) and IS982 in liaF (Rev128).

Conclusions

We demonstrated the stepwise and sequential acquisition of mutations in liaS and in cls leading to daptomycin resistance in E. faecium, and the instability of daptomycin resistance as well as the role of liaFSR inactivation in reversion to daptomycin hypersusceptibility.




Transmission of MDR MRSA between primates, their environment and personnel at a United States primate centre

2016-09-22T00:05:52-07:00

Objectives

MDR MRSA isolates cultured from primates, their facility and primate personnel from the Washington National Primate Research Center were characterized to determine whether they were epidemiologically related to each other and if they represented common local human-associated MRSA strains.

Methods

Human and primate nasal and composite environmental samples were collected, enriched and selected on medium supplemented with oxacillin and polymyxin B. Isolates were biochemically verified as Staphylococcus aureus and screened for the mecA gene. Selected isolates were characterized using SCCmec typing, MLST and WGS.

Results

Nasal cultures were performed on 596 primates and 105 (17.6%) were MRSA positive. Two of 79 (2.5%) personnel and two of 56 (3.6%) composite primate environmental facility samples were MRSA positive. Three MRSA isolates from primates, one MRSA from personnel, two environmental MRSA and one primate MSSA were ST188 and were the same strain type by conventional typing methods. ST188 isolates were related to a 2007 ST188 human isolate from Hong Kong. Both MRSA isolates from out-of-state primates had a novel MLST type, ST3268, and an unrelated group. All isolates carried ≥1 other antibiotic resistance gene(s), including tet(38), the only tet gene identified.

Conclusions

ST188 is very rare in North America and has almost exclusively been identified in people from Pan-Asia, while ST3268 is a newly reported MRSA type. The data suggest that the primate MDR MRSA was unlikely to come from primate centre employees. Captive primates are likely to be an unappreciated source of MRSA.




Heterogeneous oxacillin-resistant phenotypes and production of PBP2A by oxacillin-susceptible/mecA-positive MRSA strains from Africa

2016-09-22T00:05:52-07:00

Objectives

Recent surveillance of MRSA colonizing patients and healthcare workers in two African countries (Angola and São Tomé and Príncipe) reported the frequent recovery of oxacillin-susceptible MRSA (OS-MRSA): Staphylococcus aureus strains that gave positive results with the mecA DNA probe, but had low oxacillin MIC values characteristic of susceptible S. aureus. This apparent dissociation of the drug-resistant phenotype from mecA—the primary genetic determinant of resistance—prompted us to perform a more detailed analysis on nine of the African OS-MRSA strains.

Methods

Oxacillin MIC values were determined by Etest and population analysis profiles with and without induction of the stringent stress response by mupirocin. Biochemical profiling using SDS–PAGE followed by western blotting was used for the detection of PBP2A protein produced.

Results

Cultures of the African MRSA strains (ST88-IVa and ST8-V) showed heterogeneous oxacillin resistance in which the majority of cells exhibited low oxacillin MICs (≤0.75 mg/L), but highly resistant subpopulations were also present with oxacillin MIC values up to several hundred mg/L and with frequencies of 10–4 to 10–6. The same strains after induction of the stringent stress response by mupirocin ‘converted’ the heterogeneous phenotypes into a more homogeneous and higher level resistance. After induction by oxacillin and mupirocin, each of the nine African OS-MRSA strains produced PBP2A—the protein product of mecA.

Conclusions

The resistant phenotype of OS-MRSA resembles the phenotypes of historically early MRSA clones. The nature of genetic determinants responsible for the heterogeneous phenotypes of OS-MRSA remains to be determined.




New insights into the regulatory pathways associated with the activation of the stringent response in bacterial resistance to the PBP2-targeted antibiotics, mecillinam and OP0595/RG6080

2016-09-22T00:05:52-07:00

Objectives

The diazabicyclooctane β-lactamase inhibitor OP0595 (RG6080) also acts as an antibiotic, targeting PBP2 in Enterobacteriaceae, but this activity is vulnerable to mutational resistance. We used WGS to investigate the basis of this resistance.

Methods

Twenty OP0595-selected mutants, comprising four derived from each of five different Escherichia coli strains, were sequenced on Illumina HiSeq. Reads from each mutant were mapped to the assembled genome of the corresponding parent. A variant-calling file generated with Samtools was parsed to determine genetic alterations.

Results

Besides OP0595, the mutants consistently showed decreased susceptibility to mecillinam, which likewise targets PBP2, and grew as stable round forms in the presence of subinhibitory concentrations of OP0595. Among the 20 mutants, 18 had alterations in genes encoding tRNA synthase and modification functions liable to induce expression of the RpoS sigma factor through activation of the stringent response or had mutations suppressing inactivators of RpoS or the stringent response signal-degrading enzyme, SpoT. TolB was inactivated in one mutant: this activates RcsBC regulation and was previously associated with mecillinam resistance. The mechanism of resistance remained unidentified in one mutant. Both the RpoS and RcsBC systems regulate genes of cell division, including ftsAQZ that can compensate for loss or inhibition of PBP2, allowing survival of the challenged bacteria as stable round forms, as seen.

Conclusions

WGS identified the global stringent response signal, entailing induction of RpoS, as the main mediator of mutational resistance to OP0595 in E. coli.




Clonality of erythromycin resistance in Francisella tularensis

2016-09-22T00:05:52-07:00

Objectives

We analysed diverse strains of Francisella tularensis subsp. holarctica to assess if its division into biovars I and II is associated with specific mutations previously linked to erythromycin resistance and to determine the distribution of this resistance trait across this subspecies.

Methods

Three-hundred and fourteen F. tularensis subsp. holarctica strains were tested for erythromycin susceptibility and whole-genome sequences for these strains were examined for SNPs in genes previously associated with erythromycin resistance. Each strain was assigned to a global phylogenetic framework using genome-wide canonical SNPs. The contribution of a specific SNP to erythromycin resistance was examined using allelic exchange. The geographical distribution of erythromycin-resistant F. tularensis strains was further investigated by literature search.

Results

There was a perfect correlation between biovar II strains (erythromycin resistance) and the phylogenetic group B.12. Only B.12 strains had an A -> C SNP at position 2059 in the three copies of the rrl gene. Introducing 2059C into an rrl gene of an erythromycin-susceptible F. tularensis strain resulted in resistance. An additional 1144 erythromycin-resistant strains were identified from the scientific literature, all of them from Eurasia.

Conclusions

Erythromycin resistance in F. tularensis is caused by an A2059C rrl gene mutation, which exhibits a strictly clonal inheritance pattern found only in phylogenetic group B.12. This group is an extremely successful clone, representing the most common type of F. tularensis throughout Eurasia.




Characterization of KPC-encoding plasmids from two endemic settings, Greece and Italy

2016-09-22T00:05:52-07:00

Objectives

Global dissemination of KPC-type carbapenemases is mainly associated with the spread of high-risk clones of Klebsiella pneumoniae and of KPC-encoding plasmids. In this study, we explored the population structure of KPC-encoding plasmids from the recent epidemics of KPC-producing K. pneumoniae (KPC-Kp) in Greece and Italy, the two major European endemic settings.

Methods

Thirty-four non-replicate clinical strains of KPC-Kp representative of the early phases (2008–11) of the Greek (n = 22) and Italian (n = 12) epidemics were studied. Isolates were typed by MLST, and blaKPC-carrying plasmids were characterized by S1 profiling, PCR-based replicon typing and RFLP. Transfer experiments by conjugation or transformation were carried out with Escherichia coli recipients. Eleven plasmids, representative of all different restriction profiles, were completely sequenced.

Results

The representative Greek strains belonged to 14 sequence types (STs), with a predominance of ST258. The representative Italian strains belonged to three STs, with a predominance of clonal complex 258 (ST258, ST512). The 34 strains carried plasmids of variable size (78–166 kb), either with blaKPC-2 or blaKPC-3 gene embedded in a Tn4401a transposon. Plasmids from Greek strains were mostly of a single RFLP type (A) and resembled the archetypal pKpQIL KPC-encoding plasmid, while plasmids from Italian strains belonged to a more heterogeneous population, showing five RFLP profiles (A, C–F). Types A and C resembled pKpQIL or deletion derivatives thereof, while types D–F included plasmids with hybrid structures between pKpQIL, pKPN3 and pKPN101-IT.

Conclusions

pKpQIL-like plasmids played a major role in the dissemination of blaKPC in Greece and Italy, but evolved with different dynamics in these endemic settings.




In vitro biological evaluation of novel broad-spectrum isothiazolone inhibitors of bacterial type II topoisomerases

2016-09-22T00:05:52-07:00

Objectives

To evaluate the in vitro biological properties of a novel class of isothiazolone inhibitors of the bacterial type II topoisomerases.

Methods

Inhibition of DNA gyrase and topoisomerase IV activity was assessed using DNA supercoiling and decatenation assays. MIC and MBC were determined according to CLSI guidelines. Antibacterial combinations were assessed using a two-dimensional chequerboard MIC method. Spontaneous frequency of resistance was measured at various multiples of the MIC. Resistant mutants were generated by serial passage at subinhibitory concentrations of antibacterials and genetic mutations were determined through whole genome sequencing. Mammalian cytotoxicity was evaluated using the HepG2 cell line.

Results

Representative isothiazolone compound REDX04957 and its enantiomers (REDX05967 and REDX05990) showed broad-spectrum bactericidal activity against the ESKAPE organisms, with the exception of Enterococcus spp., as well as against a variety of other human bacterial pathogens. Compounds retained activity against quinolone-resistant strains harbouring GyrA S83L and D87G mutations (MIC ≤4 mg/L). Compounds inhibited the supercoiling activity of wild-type DNA gyrase and the decatenation function of topoisomerase IV. Frequency of resistance of REDX04957 at 4x MIC was <9.1 x 10–9. Against a panel of recent MDR isolates, REDX05967 demonstrated activity against Acinetobacter baumannii with MIC50 and MIC90 of 16 and 64 mg/L, respectively. Compounds showed a lack of cytotoxicity against HepG2 cells at 128 mg/L.

Conclusions

Isothiazolone compounds show potent activity against Gram-positive and -negative pathogens with a dual targeting mechanism-of-action and a low potential for resistance development, meriting their continued investigation as broad-spectrum antibacterial agents.




Activation of type II NADH dehydrogenase by quinolinequinones mediates antitubercular cell death

2016-09-22T00:05:52-07:00

Objectives

Quinolinequinones (QQ) have been shown to inhibit the growth of mycobacterial species, but their mode(s) of action and molecular target(s) remain unknown. To facilitate further development of QQ as antimycobacterial drugs, we investigated the molecular mechanism and target of QQ in mycobacteria.

Methods

Cell viability of Mycobacterium tuberculosis and Mycobacterium bovis bacillus Calmette–Guérin was determined in the presence of QQ8c, a representative QQ compound, and isoniazid, a frontline antitubercular drug. The effect of QQ8c on mycobacterial energetics was studied using inverted membrane vesicles. NADH oxidation and formation of reactive oxygen species (ROS) were measured in the presence and absence of KCN. Generation of ROS was measured via oxygen consumption in an oxygen electrode. The effects of QQ8c were compared with the antimycobacterial drug clofazimine in side-by-side experiments.

Results

QQ8c challenge resulted in complete sterilization of cultures with no refractory resistant population observed. QQ8c stimulated NADH oxidation by type II NADH dehydrogenase (NDH-2) and oxygen consumption in inverted membrane vesicles. Large quantities of ROS were produced in the presence of QQ8. Even when oxygen consumption was blocked with KCN, activation of NDH-2 by QQ8c occurred suggesting QQ8c was redox cycling.

Conclusions

QQ8c targets NDH-2 of the mycobacterial respiratory chain leading to activation of NADH oxidation and generating bactericidal levels of ROS in a manner similar to, but more effectively than, the antimycobacterial drug clofazimine. Our results validate respiratory-generated ROS as an avenue for antimycobacterial drug development.




Structural and sequence analysis of class A {beta}-lactamases with respect to avibactam inhibition: impact of {Omega}-loop variations

2016-09-22T00:05:52-07:00

Background

There exists a significant diversity among class A β-lactamases and the proliferation of these enzymes is a significant medical concern due to the ability of some members to efficiently hydrolyse both extended-spectrum cephalosporins and carbapenems. Avibactam is a novel non-β-lactam β-lactamase inhibitor that, in combination with ceftazidime, has recently obtained regulatory approval in the USA. Although avibactam is known to efficiently inhibit key class A enzymes, the diversity of this enzyme family warranted a more complete investigation to understand the breadth of the potential spectrum of inhibition.

Methods

Using the known residues critical for avibactam binding, a thorough structural and sequence-based conservation analysis was performed across >650 class A enzymes. Several variations that had the potential to impact avibactam inhibition were observed and representative enzymes were cloned and expressed isogenically to evaluate the impact of these variations.

Results

The majority of the key residues involved in avibactam binding were well conserved across the different sub-families of class A β-lactamases, although some differences were observed. The differences in the -loop of PER enzymes were found to impact the ability of avibactam to effectively protect β-lactams against hydrolysis. However, substitutions in a key hydrogen-bonding residue (N170) in some of the GES variants were found to not have a significant impact on avibactam inhibition.

Conclusions

Overall, the computational and experimental analyses suggest that the vast majority of class A β-lactamases should be well inhibited by avibactam, although a very small number of outliers exist.




Evaluation of different pretreatment protocols to detect accurately clinical carbapenemase-producing Enterobacteriaceae by MALDI-TOF

2016-09-22T00:05:52-07:00

Objectives

Carbapenemase-resistant bacteria are increasingly spreading worldwide causing public concern due to their ability to elude antimicrobial treatment. Early identification of these bacteria is therefore of high importance. Here, we describe the development of a simple and robust protocol for the detection of carbapenemase activity in clinical isolates of Enterobacteriaceae, suitable for routine and clinical applications.

Methods

The final protocol involves cellular lysis and enzyme extraction from a defined amount of bacterial cells followed by the addition of a benchmark drug (e.g. the carbapenem antibiotic imipenem or ertapenem). Carbapenem inactivation is mediated by enzymatic hydrolysis (cleavage) of the β-lactam common structural motif, which can be detected using MALDI-TOF MS.

Results

A total of 260 strains were studied (208 carbapenemase producers and 52 non-carbapenemase producers) resulting in 100% sensitivity and 100% specificity for the KPC, NDM and OXA-48-like PCR-confirmed positive isolates using imipenem as benchmark. Differences between the benchmark (indicator) antibiotics imipenem and ertapenem, buffer constituents and sample preparation methods have been investigated. Carbapenemase activity was further characterized by performing specific inhibitor experiments. Intraday and interday reproducibility (coefficient of variation) of the observed hydrolysis results were 15% and 30%, respectively. A comparative study of our extraction method and a recently published method using whole bacterial cells is presented and differences are discussed.

Conclusions

Using this method, an existing carbapenemase activity can be directly read from the mass spectrum as a ratio of hydrolysed product and substrate, setting an important step towards routine application in clinical laboratories.




Activity of a long-acting echinocandin, CD101, determined using CLSI and EUCAST reference methods, against Candida and Aspergillus spp., including echinocandin- and azole-resistant isolates

2016-09-22T00:05:52-07:00

Objectives

The objective of this study was to evaluate the in vitro activity of CD101, a novel echinocandin with a long serum elimination half-life, and comparator (anidulafungin and caspofungin) antifungal agents against a collection of Candida and Aspergillus spp. isolates.

Methods

CD101 and comparator agents were tested against 106 Candida spp. and 67 Aspergillus spp. isolates, including 27 isolates of Candida harbouring fks hotspot mutations and 12 itraconazole non-WT Aspergillus, using CLSI and EUCAST reference susceptibility broth microdilution (BMD) methods.

Results

Against WT and fks mutant Candida albicans, Candida glabrata and Candida tropicalis, the activity of CD101 [MIC90 = 0.06, 0.12 and 0.03 mg/L, respectively (CLSI method values)] was comparable to that of anidulafungin (MIC90 = 0.03, 0.12 and 0.03 mg/L, respectively) and caspofungin (MIC90 = 0.12, 0.25 and 0.12 mg/L, respectively). WT Candida krusei isolates were very susceptible to CD101 (MIC = 0.06 mg/L). CD101 activity (MIC50/90 = 1/2 mg/L) was comparable to that of anidulafungin (MIC50/90 = 2/2 mg/L) against Candida parapsilosis. CD101 (MIC mode = 0.06 mg/L for C. glabrata) was 2- to 4-fold more active against fks hotspot mutants than caspofungin (MIC mode = 0.5 mg/L). CD101 was active against Aspergillus fumigatus, Aspergillus terreus, Aspergillus niger and Aspergillus flavus (MEC90 range = ≤0.008–0.03 mg/L). The essential agreement between CLSI and EUCAST methods for CD101 was 92.0%–100.0% among Candida spp. and 95.0%–100.0% among Aspergillus spp.

Conclusions

The activity of CD101 is comparable to that of other members of the echinocandin class for the prevention and treatment of serious fungal infections. Similar results for CD101 activity versus Candida and Aspergillus spp. may be obtained with either CLSI or EUCAST BMD methods.




High susceptibility of MDR and XDR Gram-negative pathogens to biphenyl-diacetylene-based difluoromethyl-allo-threonyl-hydroxamate LpxC inhibitors

2016-09-22T00:05:52-07:00

Objectives

Inhibitors of uridine diphosphate-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC, which catalyses the first, irreversible step in lipid A biosynthesis) are a promising new class of antibiotics against Gram-negative bacteria. The objectives of the present study were to: (i) compare the antibiotic activities of three LpxC inhibitors (LPC-058, LPC-011 and LPC-087) and the reference inhibitor CHIR-090 against Gram-negative bacilli (including MDR and XDR isolates); and (ii) investigate the effect of combining these inhibitors with conventional antibiotics.

Methods

MICs were determined for 369 clinical isolates (234 Enterobacteriaceae and 135 non-fermentative Gram-negative bacilli). Time–kill assays with LPC-058 were performed on four MDR/XDR strains, including Escherichia coli producing CTX-M-15 ESBL and Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii producing KPC-2, VIM-1 and OXA-23 carbapenemases, respectively.

Results

LPC-058 was the most potent antibiotic and displayed the broadest spectrum of antimicrobial activity, with MIC90 values for Enterobacteriaceae, P. aeruginosa, Burkholderia cepacia and A. baumannii of 0.12, 0.5, 1 and 1 mg/L, respectively. LPC-058 was bactericidal at 1x or 2x MIC against CTX-M-15, KPC-2 and VIM-1 carbapenemase-producing strains and bacteriostatic at ≤4x MIC against OXA-23 carbapenemase-producing A. baumannii. Combinations of LPC-058 with β-lactams, amikacin and ciprofloxacin were synergistic against these strains, albeit in a species-dependent manner. LPC-058's high efficacy was attributed to the presence of the difluoromethyl-allo-threonyl head group and a linear biphenyl-diacetylene tail group.

Conclusions

These in vitro data highlight the therapeutic potential of the new LpxC inhibitor LPC-058 against MDR/XDR strains and set the stage for subsequent in vivo studies.




Pharmacodynamics and differential activity of nitrofurantoin against ESBL-positive pathogens involved in urinary tract infections

2016-09-22T00:05:52-07:00

Background

Although nitrofurantoin has been used for >60 years for the treatment of uncomplicated urinary tract infections, its pharmacodynamic properties are not fully explored. Use is increasing because of increasing resistance to other antimicrobials due to ESBLs.

Methods

We tested nine ESBL+ and two ESBL– strains in time–kill assays. Bactericidal activity and regrowth were assessed for all species and concentrations. Early-phase pharmacodynamics was analysed with a sigmoidal Emax model and the maximal killing rate, slope and EC50/MIC ratio were determined for each species.

Results

A bactericidal effect was found at ≥2x MIC for Enterobacter cloacae after 4–8 h, for Klebsiella pneumoniae after 8–10 h and for Escherichia coli after 12–16 h. Overall, no killing was observed at low sub-MIC concentrations, whereas regrowth was found at 0.5–1x MIC after a short decline in cfu. The lowest maximal killing rates were observed for E. coli (0.21 ± 0.05 h–1), followed by K. pneumoniae (0.37 ± 0.09 h–1) and E. cloacae (0.87 ± 0.01 h–1). Surprisingly, the Hill slopes for these three species were significantly different (10.45 ± 9.37, 2.68 ± 0.64 and 1.01 ± 0.06, respectively), indicating a strong concentration-dependent early-phase antibacterial activity against E. cloacae. EC50/MIC ratios were significantly lower for E. coli (0.24 ± 0.08 mg/L) and K. pneumoniae (0.27 ± 0.03 mg/L) as compared with E. cloacae (0.77 ± 0.18 mg/L).

Conclusions

Nitrofurantoin was bactericidal against all species, demonstrating an unusual differential pattern of activity with concentration-dependent-type killing behaviour against E. cloacae and time-dependent killing behaviour against E. coli, which may have significant consequences on species-dependent dosing regimens. The results also demonstrate that the pharmacodynamic properties of some drugs cannot be generalized within a family, here the Enterobacteriaceae.




Comparative efficacy of telavancin and daptomycin in experimental endocarditis due to multi-clonotype MRSA strains

2016-09-22T00:05:52-07:00

Background

MRSA strains of clonal complexes (CCs) 5, 8, 30 and 45 are leading causes of complicated endovascular infections associated with suboptimal clinical outcomes. Telavancin is a novel anti-MRSA agent that both inhibits bacterial cell wall synthesis and disrupts membranes by depolarization.

Methods

In this study, we compared the in vitro susceptibility and in vivo efficacy of telavancin versus daptomycin in an experimental rabbit infective endocarditis (IE) model caused by four MRSA strains representing each of the above CC types.

Results

All study strains were susceptible to telavancin (MICs of ≤0.12 mg/L) and daptomycin (MICs of ≤0.5 mg/L). In vitro time–kill analyses revealed that supra-MIC levels of telavancin were effective at preventing regrowth at 24 h of incubation. In the IE animal model for all CC types, treatment with telavancin produced significantly greater reductions in MRSA counts as compared with daptomycin-treated animals in all target tissues. Moreover, telavancin-treated animals had a significantly higher percentage of sterile tissue cultures versus daptomycin-treated animals (e.g. 78%–100% versus 0% sterile vegetations and 100% versus 0%–11% sterile kidneys and spleen, in the telavancin- and daptomycin-treated animals, respectively).

Conclusions

These results suggest that telavancin exhibits significantly greater efficacies versus daptomycin in treating experimental IE caused by MRSA clinical isolates across four common CC types.




Efficacy of anidulafungin in the treatment of experimental Candida parapsilosis catheter infection using an antifungal-lock technique

2016-09-22T00:05:52-07:00

Objectives

The effectiveness of anidulafungin versus liposomal amphotericin B (LAmB) for treating experimental Candida parapsilosis catheter-related infection by an antifungal-lock technique was assessed.

Methods

Two clinical strains of C. parapsilosis (CP12 and CP54) were studied. In vitro studies were used to determine the biofilm MICs (MBIC50 and MBIC90) by XTT reduction assay and LIVE/DEAD biofilm viability for anidulafungin and LAmB on 96-well microtitre polystyrene plates and silicone discs. An intravenous catheter was implanted in New Zealand white rabbits. Infection was induced by locking the catheter for 48 h with the inoculum. The 48 h antifungal-lock treatment groups included control, 3.3 mg/mL anidulafungin and 5.5 mg/mL LAmB.

Results

Anidulafungin showed better in vitro activity than LAmB against C. parapsilosis growing in biofilm on silicone discs. MBIC90 of LAmB: CP12, >1024 mg/L; CP54, >1024 mg/L. MBIC90 of anidulafungin: CP12, 1 mg/L; CP54, 1 mg/L (P ≤ 0.05). Moreover, only anidulafungin (1 mg/L) showed >90% non-viable cells in the LIVE/DEAD biofilm viability assay on silicone discs. No differences were observed between the in vitro susceptibility of anidulafungin or LAmB when 96-well plates were used. Anidulafungin achieved significant reductions relative to LAmB in log10 cfu recovered from the catheter tips for both strains (P ≤ 0.05). Only anidulafungin achieved negative catheter tip cultures (CP12 63%, CP54 73%, P ≤ 0.05).

Conclusions

Silicone discs may be a more reliable substrate for the study of in vitro biofilm susceptibility of C. parapsilosis. Anidulafungin-lock therapy showed the highest activity for experimental catheter-related infection with C. parapsilosis.




Integrated pharmacokinetic-pharmacodynamic modelling to evaluate antimicrobial prophylaxis in abdominal surgery

2016-09-22T00:05:52-07:00

Objectives

To use Monte Carlo simulation with an integrated pharmacokinetic–pharmacodynamic (PK-PD) model to evaluate guideline-recommended antimicrobial prophylaxis (AP) regimens with anaerobic coverage in abdominal surgery.

Methods

AP regimens were tested in simulated subjects undergoing elective abdominal surgery using relevant PK models and pathogen distributions in surgical site infections (SSIs). Predicted cumulative target attainment was the percentage of simulated subjects with free (unbound) antimicrobial plasma concentrations above the MICs for potential SSI pathogens.

Results

Cefazolin plus metronidazole covered SSI aerobes in 70% and the Bacteroides fragilis group in 99% of subjects, whereas cefoxitin only covered aerobes and anaerobes in 63% and 27% of cases, respectively. The broad-spectrum ceftriaxone plus metronidazole covered aerobes in 82% and anaerobes in 99% of simulations, while ertapenem covered aerobes in 88% and anaerobes in 90% of cases. Clindamycin covered the B. fragilis group in only 11% of cases. For cefazolin, 2 g doses maintained target attainment in simulated subjects from 80 to 120 kg, whereas 1 g doses were associated with lower target attainment against potential Gram-negative pathogens even in those <80 kg. For gentamicin, 3 mg/kg doses were comparable to the suggested 5 mg/kg, but superior to the traditional 1.5 mg/kg.

Conclusions

This study demonstrates the use of PK-PD to inform decisions regarding AP in abdominal surgery. In this case, the findings support avoiding cefoxitin, avoiding clindamycin for anaerobic coverage, selecting 2 g doses of cefazolin even in patients <80 kg and using 3 mg/kg doses of gentamicin.




Non-linear absorption pharmacokinetics of amoxicillin: consequences for dosing regimens and clinical breakpoints

2016-09-22T00:05:52-07:00

Objectives

To describe the population pharmacokinetics of oral amoxicillin and to compare the PTA of current dosing regimens.

Methods

Two groups, each with 14 healthy male volunteers, received oral amoxicillin/clavulanic acid tablets on two separate days 1 week apart. One group received 875/125 mg twice daily and 500/125 mg three times daily and the other group 500/125 mg twice daily and 250/125 mg three times daily. A total of 1428 amoxicillin blood samples were collected before and after administration. We analysed the concentration–time profiles using a non-compartmental pharmacokinetic method (PKSolver) and a population pharmacokinetic method (NONMEM). The PTA was computed using Monte Carlo simulations for several dosing regimens.

Results

AUC0–24 and Cmax increased non-linearly with dose. The final model included the following components: Savic's transit compartment model, Michaelis–Menten absorption, two distribution compartments and first-order elimination. The mean central volume of distribution was 27.7 L and mean clearance was 21.3 L/h. We included variability for the central volume of distribution (34.4%), clearance (25.8%), transit compartment model parameters and Michaelis–Menten absorption parameters. For 40% fT>MIC and >97.5% PTA, the breakpoints were 0.125 mg/L (500 mg twice daily), 0.25 mg/L (250 mg three times daily and 875 mg twice daily), 0.5 mg/L (500 mg three times daily) and 1 mg/L (750, 875 or 1000 mg three times daily and 500 mg four times daily).

Conclusions

The amoxicillin absorption rate appears to be saturable. The PTAs of high-dose as well as twice-daily regimens are less favourable than regimens with lower doses and higher frequency.




Accumulation of HIV-1 drug resistance after continued virological failure on first-line ART in adults and children in sub-Saharan Africa

2016-09-22T00:05:52-07:00

Objectives

Limited availability of viral load (VL) monitoring in HIV treatment programmes in sub-Saharan Africa can delay switching to second-line ART, leading to the accumulation of drug resistance mutations (DRMs). The objective of this study was to evaluate the accumulation of resistance to reverse transcriptase inhibitors after continued virological failure on first-line ART, among adults and children in sub-Saharan Africa.

Methods

HIV-1-positive adults and children on an NNRTI-based first-line ART were included. Retrospective VL and, if VL ≥1000 copies/mL, pol genotypic testing was performed. Among participants with continued virological failure (≥2 VL ≥1000 copies/mL), drug resistance was evaluated.

Results

At first virological failure, DRM(s) were detected in 87% of participants: K103N (38.7%), G190A (21.8%), Y181C (20.2%), V106M (8.4%), K101E (8.4%), any E138 (7.6%) and V108I (7.6%) associated with NNRTIs, and M184V (69.7%), any thymidine analogue mutation (9.2%), K65R (5.9%) and K70R (5.0%) associated with NRTIs. New DRMs accumulated with an average rate of 1.45 (SD 2.07) DRM per year; 0.62 (SD 1.11) NNRTI DRMs and 0.84 (SD 1.38) NRTI DRMs per year, respectively. The predicted susceptibility declined significantly after continued virological failure for all reverse transcriptase inhibitors (all P < 0.001). Acquired drug resistance patterns were similar in adults and children.

Conclusions

Patterns of drug resistance after virological failure on first-line ART are similar in adults and children in sub-Saharan Africa. Improved VL monitoring to prevent accumulation of mutations, and new drug classes to construct fully active regimens, are required.




An update to the HIV-TRePS system: the development and evaluation of new global and local computational models to predict HIV treatment outcomes, with or without a genotype

2016-09-22T00:05:52-07:00

Objectives

Optimizing antiretroviral drug combination on an individual basis in resource-limited settings is challenging because of the limited availability of drugs and genotypic resistance testing. Here, we describe our latest computational models to predict treatment responses, with or without a genotype, and compare the potential utility of global and local models as a treatment tool for South Africa.

Methods

Global random forest models were trained to predict the probability of virological response to therapy following virological failure using 29 574 treatment change episodes (TCEs) without a genotype, 3179 of which were from South Africa and were used to develop local models. In addition, 15 130 TCEs including genotypes were used to develop another set of models. The ‘no-genotype’ models were tested with an independent global test set (n = 1700) plus a subset from South Africa (n = 222). The genotype models were tested with 750 independent cases.

Results

The global no-genotype models achieved area under the receiver-operating characteristic curve (AUC) values of 0.82 and 0.79 with the global and South African tests sets, respectively, and the South African models achieved AUCs of 0.70 and 0.79. The genotype models achieved an AUC of 0.84. The global no-genotype models identified more alternative, locally available regimens that were predicted to be effective for cases that failed their new regimen in the South African clinics than the local models. Both sets of models were significantly more accurate predictors of outcomes than genotyping with rules-based interpretation.

Conclusions

These latest global models predict treatment responses accurately even without a genotype, out-performed the local South African models and have the potential to help optimize therapy, particularly in resource-limited settings.




Short-term risk of liver and renal injury in hospitalized patients using micafungin: a multicentre cohort study

2016-09-22T00:05:52-07:00

Background

Although echinocandins are generally well tolerated, there is little information on the frequency with which renal and hepatic adverse effects occur during use of micafungin or other parenteral antifungal (PAF) agents in clinical practice.

Methods

MYCOS is a multicentre cohort study of adult and paediatric patients who received micafungin or other PAFs between 2005 and 2012 at seven tertiary care hospitals from six centres in the USA. PAF cohort controls were selected through propensity score (PS) matching to micafungin recipients using clinical characteristics, other treatments, procedures and hospital service where PAF treatment was initiated. Analysis was restricted to patients without chronic liver and kidney conditions at the time of cohort entry. Treatment-emergent hepatic and renal injury was documented by changes in liver enzymes or estimated glomerular filtration rate through 30 days following completion of PAF treatment. Comparisons were quantified using the HR from a proportional hazards analysis.

Results

There were 2970 micafungin recipients PS matched to 6726 recipients of comparator PAFs. Balance was achieved in all baseline covariates between treatment groups. There were similar rates of hepatic injury (micafungin, 13 events per 100 patients and other PAF, 12 per 100; HR = 0.99; 95% CI 0.86–1.14) and lower rates of renal injury (micafungin, 63 events per 100 patients and other PAF, 65 per 100; HR = 0.93; 95% CI 0.87–0.99) for micafungin recipients versus PAF comparators.

Conclusion

For a wide spectrum of underlying conditions, we observed no increase in liver injury by micafungin and possibly a reduced risk of renal dysfunction in comparison with other PAF medications.




Rise and fall of KPC-producing Klebsiella pneumoniae in New York City

2016-09-22T00:05:52-07:00

Objectives

The study objective was to examine the epidemiological trends of KPC-producing Klebsiella pneumoniae in New York City medical centres.

Patients and methods

Single patient isolates of K. pneumoniae were collected from nine medical centres in New York City during a 3 month period from 2013 to 2014. Isolates were tested for the presence of blaKPC. Results were compared with similar surveillance studies conducted in 2006 and 2009. Infection control data, including utilization of medical devices, were analysed at a subset of hospitals.

Results

There was a progressive decline in the percentage of K. pneumoniae harbouring blaKPC from 2006 to 2013–14. For the nine hospitals that participated in all three surveillance studies, the percentages of isolates with blaKPC fell from 36% in 2006 to 25% in 2009 to 13% in 2013–14. Seven of the nine hospitals had marked declines in isolates with blaKPC, while two hospitals continued to struggle with this pathogen. These two hospitals were smaller and had longer lengths of patient stay. Device utilization rates were obtained from two hospitals that successfully controlled the spread of KPC-producing K. pneumoniae; both had ~20%–25% reduction in the usage of urinary catheters. Changes in antibiotic usage at one hospital could not explain the decline in these pathogens.

Conclusions

Over the past decade there has been a steady decline in KPC-producing K. pneumoniae in most New York City hospitals. The reason for the decline is probably multifactorial, involving a reduction in device (catheter) utilization and possibly an improvement in infection control practices.




ESBL-producing Escherichia coli ST131 versus non-ST131: evolution and risk factors of carriage among French children in the community between 2010 and 2015

2016-09-22T00:05:52-07:00

Objectives

The objective of this study was to evaluate the evolution and risk factors of ESBL-producing Enterobacteriaceae (ESBL-E) carriage in children in the community for a long period distinguishing ST131 and non-ST131 Escherichia coli.

Patients and methods

In this prospective study, rectal samples were obtained from children aged 6–24 months by community paediatricians between 2010 and 2015. Demographic characteristics and risk factors for ESBL-E carriage were collected. Distribution of β-lactamase genes, phylogenetic groups, ST131 and virulence factors of resistant E. coli was determined.

Results

We enrolled 1886 children; 144 (7.6%) harboured ESBL-E, and this rate increased from 4.8% to 10.2% between 2010 and 2015. Risk factors for ESBL-E carriage were being cared for at home [adjusted OR (aOR) = 1.8, 95% CI = 1.1–2.9], recent antibiotic use (aOR = 1.5, 95% CI = 1.0–2.1) and travel history (aOR = 1.7, 95% CI = 1.1–2.6). Among patients carrying ESBL, E. coli (98%) and CTX-M type (90%) predominated and PapGII adhesin, characteristic of pyelonephritogenic E. coli strains, was rare (7%). In 2015, E. coli isolates frequently belonged to the phylogenetic group B2 (48%), and 37% were ST131 compared with 5% in 2010. Compared with non-ESBL-producing strains, ST131 carriage was associated with hospitalization in the last 6 months (aOR = 3.5, 95% CI = 1.4–8.8).

Conclusions

Between 2010 and 2015, the carriage of ESBL-E in community children doubled because of the massive expansion of the E. coli ST131 clonal group. The risk for carrying ST131 was associated with previous hospitalization, but not, contrary to the counterpart, antibiotic treatment, daycare attendance or travel history.




Colonization with third-generation cephalosporin-resistant Enterobacteriaceae on hospital admission: prevalence and risk factors

2016-09-22T00:05:53-07:00

Objectives

The objectives of this study were to prospectively assess the rectal carriage rate of third-generation cephalosporin-resistant Enterobacteriaceae (3GCREB) in non-ICU patients on hospital admission and to investigate resistance mechanisms and risk factors for carriage.

Methods

Adult patients were screened for 3GCREB carriage at six German tertiary care hospitals in 2014 using rectal swabs or stool samples. 3GCREB isolates were characterized by phenotypic and molecular methods. Each patient answered a questionnaire about potential risk factors for colonization with MDR organisms (MDROs). Univariable and multivariable risk factor analyses were performed to identify factors associated with 3GCREB carriage.

Results

Of 4376 patients, 416 (9.5%) were 3GCREB carriers. Escherichia coli was the predominant species (79.1%). ESBLs of the CTX-M-1 group (67.3%) and the CTX-M-9 group (16.8%) were the most frequent β-lactamases. Five patients (0.11%) were colonized with carbapenemase-producing Enterobacteriaceae. The following risk factors were significantly associated with 3GCREB colonization in the multivariable analysis (P < 0.05): centre; previous MDRO colonization (OR = 2.12); antibiotic use within the previous 6 months (OR = 2.09); travel outside Europe (OR = 2.24); stay in a long-term care facility (OR = 1.33); and treatment of gastroesophageal reflux disease (GERD) (OR = 1.22).

Conclusions

To our knowledge, this is the largest admission prevalence study of 3GCREB in Europe. The observed prevalence of 9.5% 3GCREB carriage was higher than previously reported and differed significantly among centres. In addition to previously identified risk factors, the treatment of GERD proved to be an independent risk factor for 3GCREB colonization.




Surotomycin versus vancomycin for Clostridium difficile infection: Phase 2, randomized, controlled, double-blind, non-inferiority, multicentre trial

2016-09-22T00:05:53-07:00

Objectives

Clostridium difficile infection (CDI) is a major public health concern. Treatment with commonly prescribed antibiotics is associated with high rates of recurrence after initial cure. Here, we present the efficacy and safety of surotomycin, an orally administered, minimally absorbed, selective bactericidal cyclic lipopeptide, compared with vancomycin, in patients with CDI.

Methods

In this Phase 2, randomized, controlled, double-blind, non-inferiority, multicentre trial, participants received surotomycin 125 mg twice daily, surotomycin 250 mg twice daily or vancomycin 125 mg four times daily for 10 days. The primary efficacy outcome was clinical response at end of treatment. The registration number of the study on clinicaltrials.gov is NCT01085591.

Results

Clinical cure rates were similar among treatment groups (92.4% for surotomycin 125 mg twice daily, 86.6% for surotomycin 250 mg twice daily and 89.4% for vancomycin). Recurrence rates were 27.9% for surotomycin 125 mg twice daily, 17.2% for surotomycin 250 mg twice daily and 35.6% for vancomycin. The lower recurrence rate with surotomycin 250 mg twice daily versus vancomycin was statistically significant (P = 0.035). Recurrence rates were statistically similar between the surotomycin dose groups (P = 0.193). Rates of sustained clinical response at end of study were 66.7% for surotomycin 125 mg twice daily, 70.1% for surotomycin 250 mg twice daily and 56.1% for vancomycin. Incidence of adverse events was similar among treatment arms.

Conclusions

Recurrence rates of CDI were lower with surotomycin with higher sustained clinical response rates compared with vancomycin, both of which may offer potential clinical benefits.




Development and validation of the knowledge and attitudes regarding antibiotics and resistance (KAAR-11) questionnaire for primary care physicians

2016-09-22T00:05:53-07:00

Objectives

The aim of this study was to develop a novel, self-administered questionnaire to identify primary-care physicians' knowledge and attitudes regarding antibiotics and resistance (KAAR).

Methods

The study population comprised primary care physicians. The study was conducted in five phases. Phase I consisted of a systematic review and qualitative focus-group study (n = 33 physicians), in which items were formulated so as to be measured on a continuous, visual analogue scale (VAS); in Phase II, content validation and face validity were evaluated by a panel of experts, which reformulated, added and deleted items; Phase III consisted of a pilot study on a population possessing similar characteristics (n = 15); in Phase IV, we analysed reliability by means of a test–retest study (n = 91) and calculated the intraclass correlation coefficients (ICCs); and in Phase V, we assessed construct validity by applying the known-groups technique, measuring the differences between contrasting groups of physicians formed according to antibiotic prescription quality indicators (group 1, n = 156 versus group 2, n = 191).

Results

Following Phases I and II, the questionnaire contained 16 knowledge and attitude items. Participants in the pilot study (Phase III) reported no difficulty. The test–retest study (Phase IV) showed that 11 of the 16 initial knowledge and attitude items yielded an ICC > 0.5, while analysis of known-groups validity (Phase V) showed that 13 of the 16 initial items which assessed knowledge and attitudes discriminated between physicians with good and bad indicators of antibiotics prescription.

Conclusion

The final 11 item KAAR questionnaire appears to be valid, reliable and responsive.




Assessment of appropriate antimicrobial prescribing: do experts agree?

2016-09-22T00:05:53-07:00

Objectives

Little is known about the validity and reliability of expert assessments of the quality of antimicrobial prescribing, despite their importance in antimicrobial stewardship. We investigated how infectious disease doctors' assessments compared with a reference standard (modal expert opinion) and with the assessments of their colleagues.

Methods

Twenty-four doctors specialized in infectious diseases or clinical microbiology (16 specialists and 8 residents) from five hospitals were asked to assess the appropriateness of antimicrobial agents prescribed for a broad spectrum of indications in 56 paper cases. They were instructed how to handle guideline applicability and deviations. We created a reference standard of antimicrobial appropriateness using the modal assessment of 16 specialists. We calculated criterion validity and interrater and intrarater overall and specific agreement with an index expert (senior infectious disease physician) and analysed the influence of doctor characteristics on validity.

Results

Specialists agreed with the reference standard in 80% of cases (range 75%–86%), with a sensitivity and specificity of 75% and 84%, respectively. This did not differ by clinical specialty, hospital or years of experience, and residents had similar results. Specialists agreed with the index expert in 76% of cases and the index expert agreed with his previous assessments in 71% of cases.

Conclusions

Doctors specialized in infectious diseases and clinical microbiology assess the appropriateness of antimicrobials prescribed for a broad spectrum of indications with acceptable agreement and validity, regardless of their experience or hospital of employment. However, there is room for improvement, which merits attention in multidisciplinary discussions and education.






















Addressing resistance to antibiotics in systematic reviews of antibiotic interventions

2016-08-22T01:41:09-07:00

Antibiotics are among the most important interventions in healthcare. Resistance of bacteria to antibiotics threatens the effectiveness of treatment. Systematic reviews of antibiotic treatments often do not address resistance to antibiotics even when data are available in the original studies. This omission creates a skewed view, which emphasizes short-term efficacy and ignores the long-term consequences to the patient and other people. We offer a framework for addressing antibiotic resistance in systematic reviews. We suggest that the data on background resistance in the original trials should be reported and taken into account when interpreting results. Data on emergence of resistance (whether in the body reservoirs or in the bacteria causing infection) are important outcomes. Emergence of resistance should be taken into account when interpreting the evidence on antibiotic treatment in randomized controlled trials or systematic reviews.




The 2016 Garrod Lecture: The role of the healthcare epidemiologist in antimicrobial chemotherapy--a view from the USA

2016-08-22T01:41:09-07:00

Antimicrobial chemotherapy now spans 80 years and four generations. The healthcare epidemiologist has an important role to play in this field. Efforts focus in three areas: (i) minimizing the transmission of antimicrobial-resistant bacteria in healthcare settings (infection control); (ii) optimizing use of currently available antibacterial drugs (antibiotic stewardship); and (iii) recognizing and responding to opportunities for new drug development. For each area, the epidemiologist provides data that address four practical questions—‘What is the problem?’, ‘What should be done?’, ‘Is it being done?’ and ‘Is it working?’. A team approach is crucial to acting on the epidemiological data. Examples are presented to illustrate different roles of the epidemiologist, and tools and measures that have been developed to address some problems of current importance. Monitoring of quality, integrity and security of data remains a major focus. The epidemiologist will continue to have a key role in antimicrobial chemotherapy.




Pneumocystis jirovecii pneumonia: still a concern in patients with haematological malignancies and stem cell transplant recipients

2016-08-22T01:41:09-07:00

Pneumocystis jirovecii can cause life-threatening pneumonia following treatment for haematological malignancies or after HSCT. The mortality rate of P. jirovecii pneumonia (PCP) in these patients is 30%–60%, especially after HSCT. The clinical presentation of PCP in haematology differs from that associated with HIV infection, with the disease being acute and more often severe, having a lower fungal burden and being more frequently linked to treatment with corticosteroids. Most cases occur in patients not receiving adequate prophylaxis. The development of new therapies, including targeted treatments and monoclonal antibodies in various haematological diseases, justifies constant vigilance in order to identify new at-risk populations and give prophylaxis accordingly. The fifth and sixth European Conferences on Infections in Leukaemia (ECIL-5 and ECIL-6) aimed to review risk factors for PCP in haematology patients and to establish evidence-based recommendations for PCP diagnosis, prophylaxis and treatment. This article focuses on the magnitude of the problem, the main differences in clinical presentation between haematology patients and other immunocompromised populations, especially HIV-infected patients, and the main risk factors.




ECIL guidelines for the diagnosis of Pneumocystis jirovecii pneumonia in patients with haematological malignancies and stem cell transplant recipients

2016-08-22T01:41:09-07:00

The Fifth European Conference on Infections in Leukaemia (ECIL-5) convened a meeting to establish evidence-based recommendations for using tests to diagnose Pneumocystis jirovecii pneumonia (PCP) in adult patients with haematological malignancies. Immunofluorescence assays are recommended as the most sensitive microscopic method (recommendation A-II). Real-time PCR is recommended for the routine diagnosis of PCP (A-II). Bronchoalveolar lavage (BAL) fluid is recommended as the best specimen as it yields good negative predictive value (A-II). Non-invasive specimens can be suitable alternatives (B-II), acknowledging that PCP cannot be ruled out in case of a negative PCR result (A-II). Detecting β-d-glucan in serum can contribute to the diagnosis but not the follow-up of PCP (A-II). A negative serum β-d-glucan result can exclude PCP in a patient at risk (A-II), whereas a positive test result may indicate other fungal infections. Genotyping using multilocus sequence markers can be used to investigate suspected outbreaks (A-II). The routine detection of dihydropteroate synthase mutations in cases of treatment failure is not recommended (B-II) since these mutations do not affect response to high-dose co-trimoxazole. The clinical utility of these diagnostic tests for the early management of PCP should be further assessed in prospective, randomized interventional studies.




ECIL guidelines for preventing Pneumocystis jirovecii pneumonia in patients with haematological malignancies and stem cell transplant recipients

2016-08-22T01:41:09-07:00

The 5th European Conference on Infections in Leukaemia (ECIL-5) meeting aimed to establish evidence-based recommendations for the prophylaxis of Pneumocystis jirovecii pneumonia (PCP) in non-HIV-infected patients with an underlying haematological condition, including allogeneic HSCT recipients. Recommendations were based on the grading system of the IDSA. Trimethoprim/sulfamethoxazole given 2–3 times weekly is the drug of choice for the primary prophylaxis of PCP in adults (A-II) and children (A-I) and should be given during the entire period at risk. Recent data indicate that children may benefit equally from a once-weekly regimen (B-II). All other drugs, including pentamidine, atovaquone and dapsone, are considered second-line alternatives when trimethoprim/sulfamethoxazole is poorly tolerated or contraindicated. The main indications of PCP prophylaxis are ALL, allogeneic HSCT, treatment with alemtuzumab, fludarabine/cyclophosphamide/rituximab combinations, >4 weeks of treatment with corticosteroids and well-defined primary immune deficiencies in children. Additional indications are proposed depending on the treatment regimen.




ECIL guidelines for treatment of Pneumocystis jirovecii pneumonia in non-HIV-infected haematology patients

2016-08-22T01:41:09-07:00

The initiation of systemic antimicrobial treatment of Pneumocystis jirovecii pneumonia (PCP) is triggered by clinical signs and symptoms, typical radiological and occasionally laboratory findings in patients at risk of this infection. Diagnostic proof by bronchoalveolar lavage should not delay the start of treatment. Most patients with haematological malignancies present with a severe PCP; therefore, antimicrobial therapy should be started intravenously. High-dose trimethoprim/sulfamethoxazole is the treatment of choice. In patients with documented intolerance to this regimen, the preferred alternative is the combination of primaquine plus clindamycin. Treatment success should be first evaluated after 1 week, and in case of clinical non-response, pulmonary CT scan and bronchoalveolar lavage should be repeated to look for secondary or co-infections. Treatment duration typically is 3 weeks and secondary anti-PCP prophylaxis is indicated in all patients thereafter. In patients with critical respiratory failure, non-invasive ventilation is not significantly superior to intubation and mechanical ventilation. The administration of glucocorticoids must be decided on a case-by-case basis.




Ten years later: still a high prevalence of MRSA in slaughter pigs despite a significant reduction in antimicrobial usage in pigs the Netherlands

2016-08-22T01:41:09-07:00

Objectives

In 2005, 39% of pigs and 81% of the slaughter batches at Dutch slaughterhouses were MRSA positive. The objective of the present study was to investigate whether the 50% reduction of antimicrobial usage in finishing pigs in 2014 compared with 2009 in the Netherlands has led to a lower MRSA prevalence among Dutch slaughter pigs.

Methods

Nasal swabs from eight slaughter batches of on average 10 animals at seven slaughterhouses were taken and cultured using method 1, which was used in 2005, and method 2, using high-salt pre-enrichment. Suspected isolates were confirmed by PCR for two Staphylococcus aureus-specific DNA fragments and the mecA gene. A subset of MRSA isolates were further investigated using spa typing, multiple-locus variable number of tandem repeat analysis (MLVA) and antimicrobial susceptibility testing.

Results

Using methods 1 and 2, we found 461 of 558 (83%) and 552 of 558 (99%) of the pigs to carry MRSA in their nares, respectively. All 56 slaughter batches were MRSA positive. All MRSA isolates belonged to the livestock-associated MLVA complex 398, had a non-WT phenotype for tetracycline and spa type t011 predominated.

Conclusions

A very high prevalence of nasal MRSA carriage was found in Dutch slaughter pigs and therefore the reduction in antimicrobial usage at the national level has not yet had an effect on the MRSA carriage rate of pigs entering the slaughterhouse. Therefore, there is still an increased risk of MRSA carriage for personnel working at pig slaughterhouses, particularly those having contact with living animals. Method 2, using high salt pre-enrichment, detected more MRSA-positive pigs and is currently the preferred method for screening of MRSA in livestock in the Netherlands.




A novel resistance mutation in eccC5 of the ESX-5 secretion system confers ofloxacin resistance in Mycobacterium tuberculosis

2016-08-22T01:41:09-07:00

Background

Fluoroquinolone resistance in Mycobacterium tuberculosis is often conferred by DNA gyrase mutations. However, a substantial proportion of fluoroquinolone-resistant M. tuberculosis isolates do not have such mutations.

Methods

Ofloxacin-resistant and lineage-matched ofloxacin-susceptible M. tuberculosis isolates underwent WGS. Novel candidate resistance mutations were confirmed by Sanger sequencing and conferral of resistance was assessed via site-directed mutagenesis and allelic exchange. Ofloxacin MIC was determined by resazurin microtitre assay (REMA) and the effects on MICs of efflux pump inhibitors (CCCP, reserpine and verapamil) were determined.

Results

Of 26 ofloxacin-resistant isolates, 8 (31%) did not have resistance-conferring DNA gyrase mutations. The V762G mutation in Rv1783 (eccC5, encoding a protein in the ESX-5 membrane complex secretion system) was present on WGS in 8/26 (31%) resistant isolates and 0/11 susceptible isolates (P = 0.005). The mutation was identified in five isolates without DNA gyrase mutations and three isolates with such mutations; it was identified in both European–American and East Asian M. tuberculosis lineages. The ofloxacin MIC increased from 1 to 32 mg/L after introduction of the V762G mutation into M. tuberculosis H37Rv. In this strain with the V762G mutation, ofloxacin MIC did not change in the presence of efflux pump inhibitors.

Conclusions

A novel V762G mutation in Rv1783 conferred ofloxacin resistance in M. tuberculosis by a mechanism other than drug efflux. This occurred in a substantial proportion of resistant isolates, particularly those without DNA gyrase mutations.




Description of compensatory gyrA mutations restoring fluoroquinolone susceptibility in Mycobacterium tuberculosis

2016-08-22T01:41:09-07:00

Objectives

Resistance to fluoroquinolones (FQs) in Mycobacterium tuberculosis (Mtb) is mainly due to mutations in DNA gyrase (GyrA2B2), with the most common substitutions located at positions 90 and 94 in GyrA. Two clinical MDR Mtb (MDR-TB) strains harbouring an A90E or D94N substitution in GyrA were found to be surprisingly susceptible to FQs (ofloxacin MIC ≤2 mg/L). We studied the impact of the additional GyrA substitutions found in these strains (T80A and T80A + A90G, respectively) on FQ susceptibility.

Methods

Mutants of interest were generated by site-specific mutagenesis of GyrA alleles. WT and mutant TB DNA gyrase subunits were overexpressed in Escherichia coli and purified, and the in vitro susceptibility to FQs of their DNA supercoiling reaction was studied.

Results

IC50s of mutant gyrase complexes bearing GyrA D94N and A90E were 3- to 36-fold higher than WT IC50s, whereas IC50s of gyrase bearing T80A + A90G + D94N and T80A + A90E were close to the WT IC50s.

Conclusions

We demonstrated that substitutions T80A and A90G restore FQ susceptibility when associated with a substitution implicated in high-level FQ resistance. Line probe assay misclassification of MDR-TB strains as pre-XDR or XDR can be corrected by sequence analysis of gyrA.




Loss and gain of aminoglycoside resistance in global clone 2 Acinetobacter baumannii in Australia via modification of genomic resistance islands and acquisition of plasmids

2016-08-22T01:41:09-07:00

Objectives

The objective of this study was to examine the evolution of carbapenem-resistant global clone 2 (GC2) Acinetobacter baumannii in Australia focusing on the complement of aminoglycoside resistance genes and their location in resistance islands and plasmids.

Methods

Sixty-two carbapenem-resistant GC2 A. baumannii isolates with various aminoglycoside resistance profiles and resistance gene content that were recovered over the period 1999–2010 from hospitals on the east coast of Australia were examined. PCR was used to link relevant contigs retrieved from whole genomes sequenced using Illumina HiSeq and assembled de novo using Velvet. Resistance phenotypes were extended to include additional antibiotics using a disc diffusion assay.

Results

Sixty-one isolates were ST208 (formerly ST92; Oxford scheme) and one was ST425. All isolates included the oxa23 carbapenem resistance gene in Tn2006 located in the same position in AbGRI1-2, along with the ISAba1-sul2-CR2-tetA(B)-tetA(R)-CR2-strB-strA configuration. All isolates harboured either AbGRI2-1 carrying the aacC1 (gentamicin resistance) cassette or a variant derived from it via loss of some of the island content. When aacC1 was lost, aminoglycoside resistance was sometimes regained via acquisition of aadB (gentamicin, kanamycin and tobramycin resistance) in pRAY*-v1 or TnaphA6 (amikacin, kanamycin and neomycin resistance) in a repAci6 plasmid. A small cryptic plasmid or a deletion variant of this plasmid was always present and a large cryptic plasmid was also variably present.

Conclusions

The extensively antibiotic-resistant GC2 isolates from Sydney, Brisbane and Canberra appear to have arisen from a single import that was introduced into Australia in, or prior to, 1999 that then evolved and spread.




Emergence and evolution of an international cluster of MDR Bacteroides fragilis isolates

2016-08-22T01:41:09-07:00

Objectives

The aim of this study was to examine the antibiotic resistance profiles, antibiotic resistance mechanisms and possible ‘clonal’ nature of some MDR Bacteroides fragilis strains that simultaneously harboured cfiA, nimB, IS1186 and IS4351.

Methods

Antibiotic susceptibilities were determined by Etests and antibiotic resistance genes and different genetic elements were detected by applying PCR methods. The environments of the cfiA and nimB genes were also determined by sequencing. The transferability of the cfiA, nimB and tet(Q) genes was tested by conjugation. The genetic relatedness of the test strains was tested by ERIC-PCR or PFGE. The complete genome sequences of two strains (B. fragilis BF8 and O:21) were determined by next-generation sequencing.

Results

Most of the seven B. fragilis strains tested displayed multidrug resistance phenotypes; five strains were resistant to at least five types of antibiotics. Besides the common genetic constitution, ERIC-PCR implied high genetic relatedness. Similarities in some of the antibiotic resistance mechanisms [carbapenems (cfiA) and metronidazole (nimB)] also confirmed their common origin, but some other resistance mechanisms {MLSB [erm(F)] and tetracycline [tet(Q)]} and PFGE typing revealed differences. In B. fragilis BF8 and O:21, erm(F) and tet(X) genes were found with IS4351 borders, thus constituting Tn4351. All the strains were tet(Q) positive and transferred this gene in conjugation experiments, but not the cfiA and nimB genes.

Conclusions

An international cluster of MDR B. fragilis strains has been identified and characterized. This ‘clone’ may have emerged early in the evolution of division II B. fragilis strains, which was suggested by the low-complexity ERIC profiles and differences in the PFGE patterns.




Adaptive responses to cefotaxime treatment in ESBL-producing Escherichia coli and the possible use of significantly regulated pathways as novel secondary targets

2016-08-22T01:41:09-07:00

Objectives

The aim of the study was to determine how ESBL-producing Escherichia coli change the expression of metabolic and biosynthesis genes when adapting to inhibitory concentrations of cefotaxime. Secondly, it was investigated whether significantly regulated pathways constitute putative secondary targets that can be used to combat the resistant bacteria.

Methods

Strains of E. coli MG1655 encoding blaCTX-M-1 from an IncI1 plasmid and from the chromosome were challenged with cefotaxime corresponding to inhibitory concentrations, and transcriptional patterns were compared with growth without or with very low concentrations of cefotaxime by RNA sequencing. Significantly regulated pathways were inhibited with suitable inhibitors, or genes encoding the enzymes of the regulated pathways were knocked out. The ability of the bacteria to grow in the presence of cefotaxime was determined. Chequerboard assays were utilized to confirm synergies between treatments.

Results

Genes belonging to 16 different functional gene classes were significantly regulated. Protein and peptidoglycan syntheses were up-regulated and low concentrations of chloramphenicol or d-cycloserine, targeting these systems, strongly reduced the MIC of cefotaxime (>32-fold). Inhibition and/or mutations in other genes that were significantly regulated, belonging to energy synthesis, purine synthesis, proline uptake or potassium uptake, also rendered the resistant bacteria more susceptible to cefotaxime.

Conclusions

The results show that ESBL-producing E. coli adapt to treatment with cefotaxime by changing their gene expression patterns and furthermore that targeting regulated adaptive pathways may be a suitable way to identify targets for drugs that will specifically inhibit the resistant bacteria.




Glutathione-S-transferase FosA6 of Klebsiella pneumoniae origin conferring fosfomycin resistance in ESBL-producing Escherichia coli

2016-08-22T01:41:09-07:00

Objectives

The objectives of this study were to elucidate the genetic context of a novel plasmid-mediated fosA variant, fosA6, conferring fosfomycin resistance and to characterize the kinetic properties of FosA6.

Methods

The genome of fosfomycin-resistant Escherichia coli strain YD786 was sequenced. Homologues of FosA6 were identified through BLAST searches. FosA6 and FosAST258 were purified and characterized using a steady-state kinetic approach. Inhibition of FosA activity was examined with sodium phosphonoformate.

Results

Plasmid-encoded glutathione-S-transferase (GST) FosA6 conferring high-level fosfomycin resistance was identified in a CTX-M-2-producing E. coli clinical strain at a US hospital. fosA6 was carried on a self-conjugative, 69 kb IncFII plasmid. The lysR-fosA6-yjiR_1 fragment, located between IS10R and IS26, was nearly identical to those on the chromosomes of some Klebsiella pneumoniae strains (MGH78578, PMK1 and KPPR1). FosA6 shared >99% identity with chromosomally encoded FosAPMK1 in K. pneumoniae of various STs and 98% identity with FosAST258, which is commonly found in K. pneumoniae clonal complex (CC) 258 including ST258. FosA6 and FosAST258 demonstrated robust GST activities that were comparable to each other. Sodium phosphonoformate, a GST inhibitor, reduced the fosfomycin MICs by 6- to 24-fold for K. pneumoniae and E. coli strains carrying fosA genes on the chromosomes and plasmids, respectively.

Conclusions

fosA6, probably captured from the chromosome of K. pneumoniae, conferred high-level fosfomycin resistance in E. coli. FosA6 functioned as a GST and inactivated fosfomycin efficiently. K. pneumoniae may serve as a reservoir of fosfomycin resistance for E. coli.




Novel penA mutations identified in Neisseria gonorrhoeae with decreased susceptibility to ceftriaxone isolated between 2000 and 2014 in Japan

2016-08-22T01:41:09-07:00

Objectives

We examined four clinical strains of Neisseria gonorrhoeae (GU030113, GU110095, GU110332 and GU110362) isolated between 2000 and 2014 in Japan, exhibiting ceftriaxone MICs of 0.5 mg/L, for mutations of the genes associated with penicillin resistance.

Methods

The penA, mtrR, porB1b (penB), ponA and pilQ genes of the strains were sequenced. PBP2s of the strains were aligned to the PBP2s associated with decreased susceptibility to oral cephalosporins, and PBP2s of previously reported strains with decreased susceptibility to ceftriaxone.

Results

GU030113 had PBP2 pattern X with an additional substitution of A502T. GU110095 had PBP2 pattern XXVII. GU110332 had PBP2 pattern XXXIV with an additional substitution of P552S. GU110362 had PBP2 composed of pattern X (amino acid positions 1–291) and pattern V (amino acid positions 292–576). GU030113, GU110095 and GU110332 had deletion of A in the mtrR promoter, G120K and A121D or A121N in PorB1b and L421P in PBP1. GU110362 had A40D in the repressor of MtrR and L421P in PBP1. The strains did not have mutations of pilQ1 and pilQ2.

Conclusions

Addition of A502T to PBP2 pattern X in GU030113 and of P552S to PBP2 pattern XXXIV in GU110332 would possibly contribute to decreased susceptibility to ceftriaxone. In GU110095 and GU110362, it was suggested that, in addition to their altered PBP2s, the enhanced efflux pump, reduced permeability in the outer membrane, another altered target of β-lactams and/or other mechanisms not identified in the present study might contribute to decreased susceptibility.




Molecular epidemiology and mechanisms of resistance of azithromycin-resistant Neisseria gonorrhoeae isolated in France during 2013-14

2016-08-22T01:41:09-07:00

Objectives

The objective of this study was to determine the prevalence and mechanisms of azithromycin resistance of Neisseria gonorrhoeae French isolates from 2013 to 2014.

Methods

N. gonorrhoeae samples isolated in a network of laboratories were tested for susceptibility to azithromycin between April 2013 and March 2014. Fifty-four isolates that were non-susceptible to azithromycin and 18 susceptible isolates were characterized for molecular mechanisms of resistance by PCR/sequencing and genotyped using N. gonorrhoeae multiantigen sequence typing (NG-MAST).

Results

Among the 970 N. gonorrhoeae isolates, 54 (5.56%) were non-susceptible to azithromycin, 9 (1%) were resistant and 45 (4.6%) showed intermediate resistance. Azithromycin-non-susceptible isolates harboured a C2599T mutation in the rrl gene encoding the 23S rRNA alleles (5.5%), a C substitution in the mtrR promoter (5.5%), an A deletion in the mtrR promoter (53.7%) and mutations in the L4 ribosomal protein (14.8%) and in the MtrR repressor (25.9%). No isolates showed an L22 mutation or carried an erm, ere, mef(A)/(E) or mphA gene. Thirty different STs were highlighted using the NG-MAST technique. The predominant genogroups non-susceptible to azithromycin were G21 (31%), G1407 (20%) and G2400 (15%). Genogroup G2400 (15%) was revealed to be a novel cluster prevalent in the south of France and resistant to azithromycin, ciprofloxacin and tetracycline.

Conclusions

Our study highlights that the prevalence of resistance of N. gonorrhoeae to azithromycin in France is low and essentially due to multiple genetic mutations. Its dissemination occurs through three major genogroups including a novel one in France (G2400).




Development of a Luminex xTAG(R) assay for cost-effective multiplex detection of {beta}-lactamases in Gram-negative bacteria

2016-08-22T01:41:09-07:00

Objectives

The objective of this study was to design and validate a genotyping method for multiplex identification of ESBLs and carbapenemases in Gram-negative bacilli. This assay had to be (i) superior to traditional (multiplex) PCR/sequencing-based tests in turn-around time, gene coverage and the ability to detect multiple variants of the same allele, and (ii) significantly more cost-effective than commercial microarrays and WGS. The targeted β-lactamases include ESBLs (CTX-M families and subtypes, ESBL and non-ESBL SHV- and TEM-likes, OXA-1/2/7-likes, PER, VEB, GES), plasmid-mediated cephalosporinases (CMY, MOX, FOX, ACC, DHA, MIR/ACT) and carbapenemases (OXA-48, NDM, KPC, VIM, IMP).

Methods

A modular multiplex oligonucleotide ligation-PCR procedure was used, with read-out on a Luminex MAGPIX® platform. We designed 46 xTAG®-compatible probes targeting β-lactamase alleles and allele variants, and one probe targeting a conserved 16S rRNA region serving as a DNA extraction control. The assay was optimized using a collection of 48 reference strains and further validated using 105 foodborne ESBL-producing Escherichia coli isolates.

Results

The specificity and selectivity of the test are 100% and 99.4%, respectively. Multiple variants of the same allele were successfully discriminated, as exemplified by five E. coli strains encoding both blaTEM-1 and blaTEM-52 genes. The turn-around time from single colony to result is 5 h and total consumable costs remained <5 per sample.

Conclusions

We designed and validated the first Luminex-compatible genotyping assay that reliably and rapidly identifies a broad range of ESBL, pAmpC and carbapenemase producers in culture.




Benchmarking of methods for identification of antimicrobial resistance genes in bacterial whole genome data

2016-08-22T01:41:09-07:00

Objectives

Next generation sequencing (NGS) may be an alternative to phenotypic susceptibility testing for surveillance and clinical diagnosis. However, current bioinformatics methods may be associated with false positives and negatives. In this study, a novel mapping method was developed and benchmarked to two different methods in current use for identification of antibiotic resistance genes in bacterial WGS data.

Methods

A novel method, KmerResistance, which examines the co-occurrence of k-mers between the WGS data and a database of resistance genes, was developed. The performance of this method was compared with two previously described methods; ResFinder and SRST2, which use an assembly/BLAST method and BWA, respectively, using two datasets with a total of 339 isolates, covering five species, originating from the Oxford University Hospitals NHS Trust and Danish pig farms. The predicted resistance was compared with the observed phenotypes for all isolates. To challenge further the sensitivity of the in silico methods, the datasets were also down-sampled to 1% of the reads and reanalysed.

Results

The best results were obtained by identification of resistance genes by mapping directly against the raw reads. This indicates that information might be lost during assembly. KmerResistance performed significantly better than the other methods, when data were contaminated or only contained few sequence reads.

Conclusions

Read mapping is superior to assembly-based methods and the new KmerResistance seemingly outperforms currently available methods particularly when including datasets with few reads.




A novel small-molecule compound disrupts influenza A virus PB2 cap-binding and inhibits viral replication

2016-08-22T01:41:09-07:00

Objectives

The conserved residues 318–483 in the PB2 subunit of influenza A polymerase is an independently folded cap-binding domain (PB2cap) that exhibits a distinct binding mode from other host cap-binding proteins, which suggests that PB2cap might be an ideal drug target. This study aimed to identify a new class of anti-influenza inhibitors that specifically disrupts the interaction between PB2cap and host cap structures.

Methods

An innovative fluorescence polarization assay was established for primary screening, followed by cap-binding inhibitory activity, antiviral efficacy and cytotoxicity evaluations of the selected compounds. The best compound was characterized by multi-cycle virus growth assay, cross-protection test, synergism evaluation, mini-replicon assay, binding affinity analysis, docking simulation and mouse study.

Results

Several PB2 cap-binding inhibitors were discovered. The compound 7-(4-hydroxy-2-oxo-2H-chromen-3-yl)-6H,7H,8H-chromeno[3',4':5,6]pyrano[3,2-c]chromene-6,8-dione, designated PB2-39, was identified as a potent inhibitor of replication of multiple subtypes of influenza A virus, including H1N1, H3N2, H5N1, H7N7, H7N9 and H9N2 in vitro and H1N1, H5N1 and H7N9 in vivo. Combinational treatment with the influenza virus release inhibitor zanamivir and PB2-39 exerted a synergistic anti-influenza effect. Mechanistic experiments supported that PB2-39 suppressed viral polymerase activity. Docking and binding affinity analyses demonstrated that PB2-39 interacted with the PB2 cap-binding pocket, suggesting its role as a cap-binding competitor.

Conclusions

Our study provides new insights for the strategic development of novel cap-binding inhibitors of influenza A viruses.




Comparison of the antifungal activity of micafungin and amphotericin B against Candida tropicalis biofilms

2016-08-22T01:41:09-07:00

Objectives

Candida tropicalis is the fourth most common cause of candidaemia in hospitalized patients and associated mortality is high. C. tropicalis frequently causes biofilm-related infections. Echinocandins and amphotericin B show potent in vitro activity against C. albicans biofilms, but their activity against C. tropicalis biofilms has received little attention.

Methods

We studied production of biofilm by 54 C. tropicalis isolates from blood and the antifungal susceptibility of these isolates to micafungin, amphotericin B and liposomal amphotericin B. Biofilm production was measured using the crystal violet assay to determine biomass and the XTT reduction assay to determine metabolic activity. The antifungal susceptibility of planktonic and sessile cells was measured using the EUCAST EDef 7.2 procedure and XTT reduction assay, respectively. The sessile MIC endpoint of SMIC80 was defined as an 80% reduction in the metabolic activity of the biofilm treated with the antifungal compared with the control well.

Results

The three drugs were very active against the isolates in planktonic form, with micafungin showing the highest activity (P < 0.001). Micafungin was the most active agent against C. tropicalis biofilms (P < 0.001). In contrast, liposomal amphotericin B showed poor antifungal activity.

Conclusions

Micafungin was the most active drug against C. tropicalis biofilm. Although the echinocandins and liposomal amphotericin B are considered very active against Candida spp. biofilms, this is not true for C. tropicalis, as liposomal amphotericin B showed poor antifungal activity against biofilms.




What about confidence intervals? A word of caution when interpreting PTA simulations

2016-08-22T01:41:09-07:00

Objectives

In the field of antimicrobial chemotherapy, readers are increasingly confronted with population pharmacokinetic models and the ensuing simulation results with the purpose to improve the efficiency of currently used therapeutic regimens. One such type of analysis is Monte Carlo (MC) simulations in support of dose selection. At the moment, results of these MC simulations consist of predictions for the typical individual/population only. The uncertainty associated with the parameters, from which the simulations are derived, is completely ignored. Here, we highlight the importance of and the need to include parameter uncertainty in PTA simulations.

Methods

Using MC simulation with parameter uncertainty, we estimated CIs around PTA curves. The added benefit of this approach was illustrated using, on the one hand, a population pharmacokinetic model developed in-house for a β-lactam antibiotic and, on the other hand, results from a previously published PTA analysis.

Results

Our examples illustrate that proper clinical decision-making requires more than the typical PTA curve. Therefore, authors should be encouraged to provide an estimate of the uncertainty along with their simulations and to take this into account when interpreting the results. We feel that CIs around PTA curves provide this information in a comprehensive manner without requiring advanced knowledge on the underlying modelling approaches from the reader.

Conclusions

We believe that this approach should be advocated by all stakeholders in antibiotic stewardship programmes to safeguard the quality of clinical decision-making in the future.




Effect of different renal function on antibacterial effects of piperacillin against Pseudomonas aeruginosa evaluated via the hollow-fibre infection model and mechanism-based modelling

2016-08-22T01:41:09-07:00

Background

Pathophysiological changes in critically ill patients can cause severely altered pharmacokinetics and widely varying antibiotic exposures. The impact of altered pharmacokinetics on bacterial killing and resistance has not been characterized in the dynamic hollow-fibre in vitro infection model (HFIM).

Methods

A clinical Pseudomonas aeruginosa isolate (piperacillin MIC 4 mg/L) was studied in the HFIM (inoculum ~107 cfu/mL). Pharmacokinetic profiles of three piperacillin dosing regimens (4 g 8-, 6- and 4-hourly, 30 min intravenous infusion) as observed in critically ill patients with augmented renal clearance (ARC), normal renal function or impaired renal function (creatinine clearances of 250, 110 or 30 mL/min, respectively) were simulated over 7 days. The time courses of total and less-susceptible populations and MICs were determined. Mechanism-based modelling was performed in S-ADAPT.

Results

For all regimens with ARC and regimens with 8- or 6-hourly dosing with normal renal function, initial killing of ≤~2 log10 was followed by regrowth to 108–109 cfu/mL at 48 h. For 8- and 6-hourly dosing at normal renal function, the proportion of less-susceptible colonies increased ~10–100-fold above those in ARC and control arms. Regimens achieving an fCmin of ≥5x MIC resulted in bacterial killing of 3–4 log10 without regrowth and suppressed less-susceptible populations to ≤~2 log10. The mechanism-based model successfully quantified the time course of bacterial growth, killing and regrowth.

Conclusions

Only high piperacillin concentrations prevented regrowth of P. aeruginosa. Individualized dosing regimens that account for altered pharmacokinetics and aim for higher-than-standard antibiotic exposures to achieve an fCmin of ≥5x MIC were required to maximize bacterial killing and suppress emergence of resistance.




A pharmacokinetic-pharmacodynamic model characterizing the emergence of resistant Escherichia coli subpopulations during ertapenem exposure

2016-08-22T01:41:09-07:00

Objectives

Resistant subpopulations with reduced expression of outer membrane porins have been observed in ESBL-producing Escherichia coli during exposure to ertapenem. The aim of this work was to develop a pharmacokinetic–pharmacodynamic (PKPD) model to characterize the emergence of resistant E. coli during exposure to ertapenem and to predict bacterial killing following different dosing regimens of ertapenem.

Methods

Data from in vitro time–kill experiments were used to develop a mechanism-based PKPD model for three E. coli strains: a native strain, an ESBL-producing strain, and an ESBL-producing strain with reduced expression of porins OmpF and OmpC. Each strain was exposed to static ertapenem concentrations (1–512 x MIC) for 24 h using starting inocula of ~106 and 108 cfu/mL.

Results

The developed PKPD model consisted of three bacterial states: susceptible growing, less susceptible non-growing, and non-susceptible non-growing bacteria. A pre-existing bacterial subpopulation was used to describe the emergence of resistance. The PKPD model adequately characterized the data of the three E. coli strains investigated. Results from predictions suggest that the conventional dosage (1 g intravenously once daily) might result in regrowth of resistant subpopulations when used to treat infection caused by ESBL-producing strains.

Conclusions

Resistant subpopulations frequently emerged in E. coli when exposed to ertapenem, supporting that the time course of emergence of resistance should be taken into consideration when selecting dosing regimens.




Pharmacodynamics of carbapenems for the treatment of Pseudomonas aeruginosa ventilator-associated pneumonia: associations with clinical outcome and recurrence

2016-08-22T01:41:09-07:00

Objectives

This study was designed to evaluate the pharmacodynamics of doripenem, imipenem and meropenem as a predictor of clinical success, mortality, 28 day recurrence and development of resistance in patients treated for Pseudomonas aeruginosa ventilator-associated pneumonia (VAP).

Patients and methods

Previously published demographic and outcome data derived from patients treated for P. aeruginosa VAP with doripenem, imipenem or meropenem were utilized. Patient-specific data were used in conjunction with published population pharmacokinetic models to construct concentration–time profiles for each patient. Etest MICs were used to determine pharmacodynamic profiles. Classification and regression tree (CART) analysis was utilized to partition pharmacodynamics based on outcomes with P values of 0.05.

Results

Eighty-six patients were included in the analysis. Initial carbapenem MICs ranged from 0.03 to 32 mg/L. VAP recurred in 28 patients; of these, 17 patients were initially infected with susceptible organisms, and 14 of them developed resistance. CART fT>MIC partitions identified for clinical success and survival were 19.2% (P = 0.016) and 47.9% (P < 0.001), respectively. No statistically significant partitions for fT>MIC were identified for recurrence or resistance development.

Conclusions

We identified fT>MIC cut-offs for positive clinical outcomes in patients with P. aeruginosa VAP that were similar to those observed in animal models of infection for stasis (~20%) and 1 log decreases in cfu (~40%). Although in vitro studies have suggested a link between drug exposure and development of resistance, we were unable to identify such a relationship clinically.




A model-based analysis of the predictive performance of different renal function markers for cefepime clearance in the ICU

2016-08-22T01:41:09-07:00

Objectives

Several population pharmacokinetic models for cefepime in critically ill patients have been described, which all indicate that variability in renal clearance is the main determinant of the observed variability in exposure. The main objective of this study was to determine which renal marker best predicts cefepime clearance.

Methods

A pharmacokinetic model was developed using NONMEM based on 208 plasma and 51 urine samples from 20 ICU patients during a median follow-up of 3 days. Four serum-based kidney markers (creatinine, cystatin C, urea and uromodulin) and two urinary markers [measured creatinine clearance (CLCR) and kidney injury molecule-1] were evaluated as covariates in the model.

Results

A two-compartment model incorporating a renal and non-renal clearance component along with an additional term describing haemodialysis clearance provided an adequate description of the data. The Cockcroft–Gault formula was the best predictor for renal cefepime clearance. Compared with the base model without covariates, the objective function value decreased from 1971.7 to 1948.1, the median absolute prediction error from 42.4% to 29.9% and the between-subject variability in renal cefepime clearance from 135% to 50%. Other creatinine- and cystatin C-based formulae and measured CLCR performed similarly. Monte Carlo simulations using the Sanford guide dose recommendations indicated an insufficient dose reduction in patients with a decreased kidney function, leading to potentially toxic levels.

Conclusions

The Cockcroft–Gault formula was the best predictor for cefepime clearance in critically ill patients, although other creatinine- and cystatin C-based formulae and measured CLCR performed similarly.




Hepatic cyst penetration of cefazolin in patients receiving aspiration sclerotherapy

2016-08-22T01:41:09-07:00

Background

Hepatic cyst infection is a potentially severe complication in cystic disease. Treatment demands effective antibiotic concentrations within the infected cyst.

Objectives

The aim of this study was to use elective hepatic cyst drainage as a unique pharmacokinetic model to investigate whether cefazolin, a first-generation cephalosporin, is able to penetrate hepatic cysts.

Patients and methods

Patients scheduled to undergo percutaneous aspiration sclerotherapy of a symptomatic non-infected, non-neoplastic hepatic cyst were eligible for this study. All participants received a single perioperative prophylactic dose of cefazolin (1000 mg, intravenously). We collected blood and cyst fluid samples to determine total and unbound cefazolin concentrations using HPLC. The primary outcome was hepatic cyst penetration, expressed as the ratio (%) of unbound concentration of cefazolin in cyst fluid to plasma (both in mg/L).

Results

We included eight patients [male = 25%, median age = 60 years (IQR 54–75), median estimated glomerular filtration rate = 97 mL/min/1.73 m2 (IQR 67–102) and median serum albumin = 40 g/L (IQR 37–40)]. We detected low concentrations of unbound cefazolin in cyst fluid (≤1.0 mg/L). The median plasma unbound cefazolin peak level (immediately after cefazolin administration) was 36.6 mg/L (IQR 23.7–54.1) and the level at the time of cyst fluid aspiration was 16.1 mg/L (IQR 13.0–20.1). In total, the hepatic cyst penetration of free cefazolin was only 2.2% (IQR 0.7–5.2).

Conclusions

We developed a study model to investigate the penetration of antibiotics into hepatic cysts. Cefazolin did not reach adequate intracystic concentrations. Future studies should explore alternatives.




Characterization of the haematological profile of 21 days of tedizolid in healthy subjects

2016-08-22T01:41:09-07:00

Objectives

Tedizolid is a novel oxazolidinone antibacterial. Oxazolidinones carry concerns for time-dependent myelosuppression. To further explore tedizolid's haematological tolerability, we analysed data from a 21 day study comparing safety and pharmacokinetics of tedizolid and linezolid.

Methods

This was a Phase 1 study in healthy volunteers comparing five treatments (each n = 8) over 21 days: tedizolid at 200, 300 or 400 mg once daily; linezolid at 600 mg twice daily; and placebo. Routine laboratory haematological parameters (platelet, absolute neutrophil, white blood cell, red blood cell and reticulocyte counts) were compared between groups. Adverse haematological outcomes were pre-specified as any parameter below the standard lower limits of normal (LLN), substantially abnormal (<50% LLN for neutrophils; <75% LLN for other parameters) or ≥50% below baseline (platelets only). ClinicalTrials.gov identifier: NCT00671814.

Results

During the 21 day study period, pre-specified adverse platelet outcomes were observed in the linezolid (n = 2), tedizolid 300 mg (n = 1) and tedizolid 400 mg (n = 3) groups. Mean platelet counts decreased over time in a dose-dependent manner for tedizolid, with higher doses being similar to linezolid. The magnitude of platelet count decreases from baseline was influenced by unbound drug trough plasma concentrations, which were generally higher in subjects with at least a 20% decrease in platelet count. Substantially abnormal haematological parameters were only observed with linezolid and tedizolid 400 mg. One linezolid and two tedizolid 400 mg subjects discontinued due to meeting criteria for pre-specified adverse haematological outcomes.

Conclusions

Although limited to small groups of healthy volunteers, these exploratory results support clinical study of extended treatment durations with tedizolid at 200 mg once daily.




Microbiological efficacy and tolerability of a single-dose regimen of 1 g of ceftriaxone in men with gonococcal urethritis

2016-08-22T01:41:09-07:00

Objectives

We treated men with gonococcal urethritis with a single-dose regimen of 1 g of ceftriaxone, which is recommended as the first-line treatment for gonorrhoea in Japan, to determine its microbiological outcomes and tolerability.

Methods

We enrolled 255 men with gonococcal urethritis and treated them with a single-dose regimen of 1 g of ceftriaxone. We evaluated its microbiological outcomes and tolerability. We also determined ceftriaxone MICs for pretreatment isolates of Neisseria gonorrhoeae collected from the patients.

Results

The microbiological efficacy of the ceftriaxone regimen, which was determined between 5 and 9 days after treatment in 111 men based on the Japanese guideline for clinical research on antimicrobial agents in urogenital infections, was 100%. In the 194 men who returned to the clinic between 2 and 41 days after treatment, 191 (98.5%; 95% CI 96.8%–100%) were negative for N. gonorrhoeae after treatment. Ceftriaxone MICs determined for 136 pretreatment isolates obtained from these 194 men ranged from 0.001 to 0.25 mg/L. One isolate persisting after treatment exhibited a ceftriaxone MIC of 0.008 mg/L. For two isolates persisting after treatment, ceftriaxone MICs were not determined. Seven adverse events were observed in 7 (3.2%) of the 220 men treated with the ceftriaxone regimen. Four men had diarrhoea classified as grade 1. Three had urticaria during ceftriaxone administration, with one event classified as grade 1 and two events classified as grade 3.

Conclusions

A single-dose regimen of 1 g of ceftriaxone was microbiologically effective against gonococcal urethritis and was safe and tolerable.




Treatment of MDR urinary tract infections with oral fosfomycin: a retrospective analysis

2016-08-22T01:41:10-07:00

Objectives

Limited options for treating MDR organisms have led clinicians to turn to older antimicrobial agents that may display activity against such infections. One such agent is fosfomycin, an oral drug with activity against a variety of Gram-positive and -negative bacteria, but only approved for use in the USA for urinary tract infection (UTI) due to Escherichia coli and Enterococcus faecalis. The purpose of this study was to assess the efficacy of fosfomycin treatment of MDR UTI and identify predictors of outcome.

Patients and methods

A retrospective review was performed of patients treated for MDR UTI at a large quaternary medical centre between 1 January 2010 and 30 September 2014. Sixty patients received 69 courses of fosfomycin in the inpatient or outpatient setting for UTIs due to Enterobacteriaceae, Pseudomonas aeruginosa or VRE.

Results

In the 58 patients for whom follow-up data were available, the treatment success rate (no persistent or recurrent infection) was 55%. Chronic kidney disease was associated with persistent infection (OR = 3.56, 95% CI = 1.02–12.40, P = 0.04). No other factors, including comorbidities, infecting organism, fosfomycin MIC or number of doses of fosfomycin received, were associated with recurrent infection or treatment failure.

Conclusions

This study supports the use of fosfomycin as an oral option for treating MDR UTIs. Additional studies are required to assess the optimal dosing and utility of combination therapy to decrease the incidence of treatment failure.




An observational study of the universal use of octenidine to decrease nosocomial bloodstream infections and MDR organisms

2016-08-22T01:41:10-07:00

Objectives

To investigate the effect of universal decolonization with octenidine on the incidence of ICU-acquired bloodstream infections (BSI) and MDR organisms (MDRO).

Methods

A system-wide change in practice was performed in the ICUs of a university hospital with three campuses (eight medical ICUs and nine surgical ICUs). All ICUs had a general admission screening strategy for MRSA with subsequent isolation in the 12 month baseline period, which was stopped. After a wash-in period of 1 month, decolonization of the nose with octenidine nasal gel and octenidine wash cloths was introduced. The endpoints were ICU-acquired BSI and ICU-acquired MDRO isolates from clinical cultures. Segmented regression analysis of interrupted time series was used to assess the effect of intervention.

Results

A total of 29 532 ICU patients (16 677 surgical and 12 855 medical) were included in the study. The baseline incidence density of ICU-acquired BSI was 5.1 per 1000 patient days and the baseline ICU-acquired MRSA rate was 0.97 per 1000 patient days. Whereas no significant effect on either outcome was found in surgical ICUs, we identified a significant effect on ICU-acquired BSI for the intervention in medical ICUs by means of multivariate analysis (incidence rate ratio 0.78; 95% CI 0.65–0.94). In addition, the intervention was also effective in decreasing ICU-acquired MRSA in medical ICUs (incidence rate ratio 0.58; 95% CI 0.41–0.82). No effect on ICU-acquired VRE and Gram-negative MDRO was found.

Conclusions

System change was successful by decreasing infection rates in medical ICUs and improving the management in all ICUs.




Outbreak of IMP-producing carbapenem-resistant Enterobacter gergoviae among kidney transplant recipients

2016-08-22T01:41:10-07:00

Objectives

The objective of this study was to investigate a prolonged outbreak of carbapenem-resistant Enterobacter gergoviae (CREG) involving kidney transplant recipients (KTRs) between 2009 and 2014.

Methods

A case–control study was undertaken. Controls (n = 52) were selected from CREG-negative KTRs. Surveillance cultures for CREG were collected weekly. Colonization was defined as isolation of CREG from surveillance samples or from clinical specimens, with no evidence of infection. We also investigated infection control practices at the facility.

Results

Of 26 identified cases, 13 had had no known contact with another CREG-positive patient before the first positive culture. Seven patients (27%) developed infection. The site most often colonized was the urinary tract. During the study period two clusters were identified, one in 2009 and another in 2013–14. DNA sequencing revealed blaIMP-1 in all CREG tested. No environmental or hand cultures tested positive for CREG. An audit of infection control practices detected flaws in the handling and cleaning of urinary tract devices. Multivariate analysis identified advanced age, ureteral stent use, retransplantation and male gender as risk factors for CREG acquisition.

Conclusions

An outbreak among KTRs caused by an unusual species of MDR bacteria may have resulted from a common source of contamination related to urinary tract devices.




Carriage of antimicrobial-resistant commensal bacteria in Dutch long-term-care facilities

2016-08-22T01:41:10-07:00

Objectives

The objective of this study was to assess carriage of antimicrobial-resistant commensal microorganisms, i.e. Escherichia coli and Staphylococcus aureus, and its predictors in long-term-care facilities (LTCFs).

Methods

Nasal swabs and/or urine or incontinence samples were collected from participating residents in 111 LTCFs and tested for the presence of S. aureus and/or E. coli, respectively. Antimicrobial resistance to eight antimicrobials was linked to antimicrobial usage in the year preceding sampling and to LTCF characteristics. Using multilevel logistic regression, predictors of carriage of ESBL-producing E. coli in LTCFs were identified.

Results

S. aureus was identified in 1269/4763 (26.6%) nasal swabs, including 13/4763 (0.3%) MRSA carriers in 9/107 (8%) LTCFs. Of the 5359 urine/incontinence samples, 2934 (55%) yielded E. coli, including 123 (4.2%) producing ESBL, which were found in 53/107 locations (range 1%–33%). For all but one antimicrobial (i.e. nitrofurantoin) >20% of isolated E. coli were resistant. Multilevel multivariable logistic regression identified two predictors of carriage of ESBL-producing E. coli: (i) antimicrobial usage (OR 1.8, 95% CI 1.1–3.0 for each extra 50 DDD/1000 residents/day); and (ii) presence of MRSA carriers in the LTCFs (OR 2.4, 95% CI 1.0–5.6).

Conclusions

The low proportion of 4.2% ESBL-producing E. coli and the low prevalence of 0.3% MRSA carriage found in LTCF residents suggest that Dutch LTCFs are not yet an important reservoir of MDR potential pathogens. Nevertheless, the large variation between LTCFs warrants close monitoring of antimicrobial resistance in LTCFs. Integrated surveillance, i.e. linking data sources on antimicrobial usage, microbiological testing, clinical background data and epidemiological data, is needed.




Gram-negative prosthetic joint infections managed according to a multidisciplinary standardized approach: risk factors for failure and outcome with and without fluoroquinolones

2016-08-22T01:41:10-07:00

Objectives

To describe the outcome and risk factors for treatment failure of 76 Gram-negative bacilli (GNB) prosthetic joint infections (PJIs) managed with a curative intent according to a standardized protocol derived from published guidelines.

Methods

We analysed data from all the cases of GNB-PJI treated surgically over an 8 year period. Treatment failure was defined as persistence or recurrence of PJI signs during follow-up, resulting in additional surgery and/or antibiotic administration or death.

Results

Treatment failure within the follow-up period (median = 2.6 years) was observed in 16 of 76 (21.1%) patients. The failure rate was similar whether the patients were treated with fluoroquinolones in the whole cohort (22.4% versus 16.7%, P = 0.75) and after stratification according to the surgical procedure. The low failure rate observed in patients not receiving fluoroquinolones might be explained by the standardized attitude of maintaining intravenous β-lactams throughout treatment duration (median = 90 days). In multivariate analysis, C-reactive protein level ≥175 mg/L was significantly associated with treatment failure (adjusted HR = 7.75, 95% CI = 2.66–22.59, P < 0.0001).

Conclusions

Management according to standardized procedures may improve the prognosis of GNB-PJI. Intravenous β-lactams, continued for 3 months, should be considered an effective alternative to fluoroquinolones.




Reduction in post-operative acute kidney injury following a change in antibiotic prophylaxis policy for orthopaedic surgery: an observational study

2016-08-22T01:41:10-07:00

Objectives

Evidence has shown that a prophylactic antibiotic regimen of flucloxacillin and gentamicin for orthopaedic surgery was associated with increased rates of post-operative acute kidney injury (AKI). This resulted in changes in the national antibiotic policy recommendation for orthopaedic surgical prophylaxis. This study aimed to assess whether this change from flucloxacillin and gentamicin to co-amoxiclav was associated with changes in the rates of AKI and Clostridium difficile infection (CDI).

Methods

An observational study and interrupted time series analyses were used to assess rates of post-operative AKI separately in patients undergoing neck of femur (NOF) repair and other orthopaedic operations that required antibiotic prophylaxis. Incidence rate ratios were used to evaluate changes in CDI rates.

Results

Following the change in policy, from flucloxacillin and gentamicin to co-amoxiclav, there was a relative change in rates of post-operative AKI of –63% (95% CI –77% to –49%) at 18 months in the other orthopaedic operations group. In the NOF repair group, there was no change in the rate of post-operative AKI [–10% (95% CI –35%–15%)] at 18 months. The incident rate ratio for CDI in the other orthopaedic operations group was 0.29 (95% CI 0.09–0.96) and in the NOF repair group was 0.76 (95% CI 0.28–2.08).

Conclusions

The use of co-amoxiclav for antibiotic prophylaxis in orthopaedic surgery was associated with a decreased rate of post-operative AKI compared with flucloxacillin and gentamicin and was not associated with increased rates of CDI.




Impact of the PROVAUR stewardship programme on linezolid resistance in a tertiary university hospital: a before-and-after interventional study

2016-08-22T01:41:10-07:00

Background

There is little evidence of the impact of antimicrobial stewardship programmes on antimicrobial resistance.

Objectives

To study the efficacy and safety of a package of educational and interventional measures to optimize linezolid use and its impact on bacterial resistance.

Methods

A quasi-experimental study was designed and carried out before and after implementation of a stewardship programme in hospitalized patients with Gram-positive infections treated with linezolid.

Results

The intervention reduced linezolid consumption by 76%. The risk of linezolid-resistant CoNS isolates (OR = 0.37; 95% CI = 0.27–0.49; P < 0.001) and Enterococcus faecalis (OR = 0.44; 95% CI = 0.21–0.90; P = 0.03) during the intervention period was lower than in the pre-intervention period.

Conclusions

A programme to optimize linezolid use can contribute to reducing the resistance rate of CoNS and E. faecalis to this antibiotic.




Increase in antibiotic prescriptions in out-of-hours primary care in contrast to in-hours primary care prescriptions: service evaluation in a population of 600 000 patients

2016-08-22T01:41:10-07:00

Objectives

The objective of this study was to describe the frequency and nature of antibiotic prescriptions issued by a primary care out-of-hours (OOH) service and compare time trends in prescriptions between OOH and in-hours primary care.

Methods

We performed a retrospective audit of 496 931 patient contacts with the Oxfordshire OOH primary care service. Comparison of time trends in antibiotic prescriptions from OOH primary care and in-hours primary care for the same population was made using multiple linear regression models fitted to the monthly data for OOH prescriptions, OOH contacts and in-hours prescriptions between September 2010 and August 2014.

Results

Compared with the overall population contacting the OOH service, younger age, female sex and patients who were less deprived were independently correlated with an increased chance of a contact resulting in prescription of antibiotics. The majority of antibiotics were prescribed to patients contacting the service at weekends. Despite a reduction in patient contacts with the OOH service [an estimated decrease of 486.5 monthly contacts each year (95% CI –676.3 to –296.8), 5.0% of the average monthly contacts], antibiotic prescriptions from this service rose during the study period [increase of 37.1 monthly prescriptions each year (95% CI 10.6–63.7), 2.5% of the average monthly prescriptions]. A matching increase was not seen for in-hours antibiotic prescriptions; the difference between the year trends was significant (Z test, P = 0.002).

Conclusions

We have demonstrated trends in prescribing that could represent a partial displacement of antibiotic prescribing from in-hours to OOH primary care. The possibility that the trends we describe are evident nationally should be explored.




Efficacy of OZ439 (artefenomel) against early Plasmodium falciparum blood-stage malaria infection in healthy volunteers

2016-08-22T01:41:10-07:00

Objectives

OZ439, or artefenomel, is an investigational synthetic ozonide antimalarial with similar potency, but a significantly improved pharmacokinetic profile, compared with artemisinins. We wished to measure key pharmacokinetic and pharmacodynamic parameters and the pharmacokinetic/pharmacodynamic relationship of artefenomel in humans to guide the drug's further development as combination therapy in patients.

Patients and methods

We tested artefenomel in the human induced blood-stage malaria (IBSM) model. Plasmodium infection was monitored by quantitative PCR (qPCR) and upon reaching 1000 parasites/mL single doses of 100, 200 and 500 mg of artefenomel were administered orally with evaluation of drug exposure and parasitaemia until rescue treatment after 16 days or earlier, if required.

Results

A single 100 mg dose had only a transient effect, while the 200 mg dose resulted in a significant reduction in parasitaemia before early recrudescence. At the highest (500 mg) dose, initial clearance of parasites below the limit of detection of qPCR was observed, with a 48 h parasite reduction ratio (PRR48) >10 000 and a parasite clearance half-life of 3.6 h (95% CI 3.4–3.8 h). However, at this dose, recrudescence was seen in four of eight subjects 6–10 days after treatment. Pharmacokinetic/pharmacodynamic modelling predicted an MIC of 4.1 ng/mL.

Conclusions

These results confirm the antimalarial potential of artefenomel for use in a single-exposure combination therapy. The observations from this study support and will assist further clinical development of artefenomel.




Discontinuation of empirical antifungal therapy in ICU patients using 1,3-{beta}-D-glucan

2016-08-22T01:41:10-07:00

Background

Empirical antifungal therapy in high-risk ICU patients is an attractive strategy, but overuse of antifungal agents is a potential problem.

Objectives

We evaluated if ICU patients at high risk to develop candidaemia identified by a prediction rule could discontinue empirical antifungal therapy on the basis of repeatedly negative 1-3-β-d-glucan (BDG) tests.

Methods

We conducted a multicentre cohort study in 85 ICU patients receiving antibiotics or with central venous catheter plus two additional factors (dialysis, parenteral nutrition, surgery, pancreatitis or receipt of corticosteroids or other immunosuppressive agents) plus either fever, hypothermia, hypotension, acidosis, elevated C-reactive protein or leucocytosis. Blood cultures (days 1 and 2) and BDG (days 1–3, baseline period) were performed and anidulafungin was given. On day 4, patients with negative blood cultures and BDG discontinued antifungal therapy. Registered in ClinicalTrials.gov (NCT01734525).

Results

The incidence of candidaemia was 8.2% in patients selected versus 0.5% in patients without entry criteria (16.9 times higher). Sixty-four patients (75.3%) had baseline positive BDG, including 7 with candidaemia. All 21 patients with baseline negative BDG discontinued anidulafungin on day 4. None developed candidaemia until day 30.

Conclusions

Early discontinuation of empirical echinocandin therapy in high-risk ICU patients based on consecutive negative BDG tests may be a reasonable strategy, with great potential to reduce the overuse of echinocandins in ICU patients. Prospective studies with a higher number of patients are needed.




A cohort study on breakthrough invasive fungal infections in high-risk patients receiving antifungal prophylaxis

2016-08-22T01:41:10-07:00

Objectives Antifungal prophylaxis is recommended for haematological patients at high risk of invasive fungal infections (IFIs). Incidence, optimal therapeutic management and outcome of breakthrough IFIs (bIFIs) are largely unknown. Methods To assess bIFI incidence, treatment and outcomes, data on patients undergoing AML remission–induction and consolidation chemotherapy and from allogeneic HSCT recipients on antifungal prophylaxis with itraconazole, micafungin or posaconazole were extracted from the Cologne Cohort of Neutropenic Patients (CoCoNut). bIFIs were classified according to revised EORTC/MSG criteria. Results From January 2004 to April 2013, 250 AML patients with 329 hospitalizations and 409 HSCT patients with 496 hospitalizations were identified. In AML patients, there were 16 (6.4%) proven or probable bIFIs and 44 (17.6%) possible bIFIs. In HSCT patients, there were 14 (3.4%) proven or probable bIFIs and 37 (9.0%) possible bIFIs. Proven cases included five candidaemias, two mucormycoses, three aspergilloses and one fusariosis. The most frequent choice for bIFI treatment was liposomal amphotericin B in AML patients (21/60; 35.0%) and continuation of posaconazole prophylaxis in HSCT patients (16/51; 31.4%). In HSCT recipients, survival on day 365 was significantly lower in bIFI patients (AML, 63.3% versus 70.0%; P = 0.297; HSCT, 49.0% versus 66.8%; P = 0.012). Comparison of continuation of prophylaxis versus switch of antifungal class as first-line treatment showed no significant difference regarding response to treatment and survival. Conclusions Rates of bIFIs observed in our population were comparable to previous data. There was no clear shift towards rare species, as previously reported. A high variety of treatment approaches was observed. [...]



High rates of hepatitis C virus (HCV) cure using direct-acting antivirals in HIV/HCV-coinfected patients: a real-world perspective

2016-08-22T01:41:10-07:00

Objectives There are few data on the real-world experience of FDA-approved oral hepatitis C virus (HCV) direct-acting antiviral (DAA) drug combinations in HIV/HCV-coinfected patients. We evaluated the safety and efficacy of DAA therapies in a cohort of HIV/HCV patients in a large urban clinic in Chicago. Methods HIV/HCV-coinfected adults (≥18 years) enrolled in the Northwestern University Viral Hepatitis Registry between January 2013 and June 2015 were analysed. Treated patients received one of the following DAA combinations: sofosbuvir/ledipasvir, sofosbuvir/ribavirin, sofosbuvir/simeprevir or paritaprevir/ritonavir/ombitasvir/dasabuvir ± ribavirin. The primary outcome was sustained virological response at 12 weeks after DAA completion (SVR12). Results Seventy-seven HIV/HCV patients were evaluated for DAA therapy. Most patients were male (62/77, 81%) and infected with HCV genotype 1 (67/77, 87%). Some 32/77 (42%) were cirrhotic and 29/77 (38%) had received prior treatment with an IFN-containing regimen. DAA therapy was more likely to be started in Caucasians than persons of other ethnicities (P = 0.01). The overall SVR12 rate was 92% in 52 patients who completed therapy and had follow-up by the end of the study: sofosbuvir/simeprevir, 32/33 (97%); sofosbuvir/ribavirin, 4/7 (57%); sofosbuvir/ledipasvir, 11/11 (100%); and paritaprevir/ritonavir/ombitasvir/dasabuvir, 1/1 (100%). Four patients relapsed after therapy with sofosbuvir/simeprevir (n = 1) or sofosbuvir/ribavirin (n = 3). Adverse events were uncommon and did not result in DAA treatment interruption or discontinuation. Conclusions The HCV DAA combinations of sofosbuvir/ledipasvir and sofosbuvir/simeprevir were highly effective and well tolerated in this diverse population of HIV/HCV-coinfected patients, many of whom had advanced liver disease. HIV coinfection should not be consider[...]



Dolutegravir as monotherapy in HIV-1-infected individuals with suppressed HIV viraemia

2016-08-22T01:41:10-07:00

Background Reducing drug burden is a key challenge for achieving lifelong suppressive HIV therapy. Dolutegravir, with a high potency, long half-life and high genetic barrier, offers potential for monotherapy. Methods This observational single-centre study enrolled all patients with HIV RNA (viral load) <50 copies/mL for at least 12 months, with CD4 >350 cells/mm3 and with no failure under integrase inhibitor therapy who had switched from suppressive ART to dolutegravir monotherapy (50 mg/day). Primary outcome was proportion of patients with viral load <50 copies/mL at week 24. Results Twenty-eight patients treated for a median ART duration of 17 years (IQR 11–20), virally suppressed for a median of 79 months (IQR 42–95) and with a median CD4 count of 624 cells/mm3 (IQR 524–761), were enrolled. Baseline ART consisted of a three-drug (n = 10), two-drug (n = 10) or single-drug (n = 8) regimen with integrase inhibitor exposure in 13 patients. The proportion of patients maintaining viral load <50 copies/mL was 96% (95% CI 79%–100%) at week 4, 100% (95% CI = 85%–100%) at week 8, 93% (95% CI 76%–99%) at week 12 and 92% (75–99) at week 24. Three patients (3.70%; 95% CI 3.4%–10.8%) with prior integrase inhibitor experience had HIV RNA rebound with the presence of resistance mutations. Genotyping of HIV DNA using the Sanger method or ultradeep sequencing showed no integrase inhibitor resistance-associated mutations (RAMs) except for the mutation 74I in a patient on a suppressive elvitegravir regimen. The median within- and between-subject variability of dolutegravir C24 was 25% and 34%, respectively. Nine patients with a year of follow-up remained virally suppressed. Conclusions Dolutegravir has the potency to be further investigated as a single ART in randomized studies,[...]



Factors associated with virological response to a switch regimen containing maraviroc for antiretroviral-experienced HIV-1-infected patients

2016-08-22T01:41:10-07:00

Objectives There are few data on clinical and virological factors associated with maraviroc virological response (VR) in clinical practice. This study aimed to identify factors associated with VR in 94 treatment-experienced, but CCR5 inhibitor-naive, HIV-1 patients switched to maraviroc-containing regimens. Methods Patients with HIV-1 RNA viral load (VL) <50 copies/mL switching to an antiretroviral treatment containing maraviroc were followed. VR was defined at month 3 as VL <50 copies/mL. The impact of age, baseline tropism, zenith VL, nadir CD4 cell count and CD4 cell count, HIV subtype (B versus non-B), genotypic susceptibility score of treatment, once- or twice-daily treatment and presence of raltegravir in optimized background therapy on VR was investigated. Results Baseline characteristics were: median age 49 years (range 25–73 years), median CD4 cell count 481 cells/mm3 (range 57–1830 cells/mm3) and median nadir CD4 cell count 99 cells/mm3 (range 3–585). Maraviroc was administered twice daily in 88 of 94 patients and once daily in 6 of 94 patients (300 mg/day for 4 of 6 and 150 mg/day for 2 of 6). At month 3, 89.4% of patients were responders. A better VR to a switch regimen containing maraviroc was associated with the B subtype (P = 0.0216) and a lower zenith VL (median of 5.24 and 5.70 log10 copies/mL for patients in success or in failure, respectively) in univariate analysis. Only B subtype was associated with a better VR in multivariate analysis. Conclusions This study evidenced the efficacy of a switch regimen containing maraviroc in clinical practice. VR was better for patients with a lower zenith VL and B subtype. [...]



CD4 cell count at initiation of ART, long-term likelihood of achieving CD4 >750 cells/mm3 and mortality risk

2016-08-22T01:41:10-07:00

Objectives We sought to evaluate associations between CD4 at ART initiation (AI), achieving CD4 >750 cells/mm3 (CD4 >750), long-term immunological recovery and survival. Methods This was a prospective observational cohort study. We analysed data from ART-naive patients seen in 1996–2012 and followed ≥3 years after AI. We used Kaplan–Meier (KM) methods and log-rank tests to compare time to achieving CD4 >750 by CD4 at AI (CD4-AI); and Cox regression models and generalized estimating equations to identify factors associated with achieving CD4 >750 and mortality risk. Results Of 1327 patients, followed for a median of 7.9 years, >85% received ART for ≥75% of follow-up time; 64 died. KM estimates evaluating likelihood of CD4 >750 during 5 years of follow-up, stratified by CD4-AI <50, 50–199, 200–349, 350–499 and 500–750, were 20%, 25%, 56%, 80% and 87%, respectively (log-rank P < 0.001). In adjusted models, CD4-AI ≥200 (versus CD4-AI <200) was associated with achievement of CD4 >750 [adjusted HR (aHR) = 4.77]. Blacks were less likely than whites to achieve CD4 >750 (33% versus 49%, aHR = 0.77). Mortality rates decreased with increasing CD4-AI (P = 0.004 across CD4 strata for AIDS causes and P = 0.009 for non-AIDS death causes). Among decedents with CD4-AI ≥50, 56% of deaths were due to non-AIDS causes. Conclusions Higher CD4-AI resulted in greater long-term CD4 gains, likelihood of achieving CD4 >750, longer survival and decreased mortality regardless of cause. Over 80% of persons with CD4-AI ≥350 achieved CD4 >750 by 4 years while 75% of persons with CD4-AI <200 did not. These data confirm the hazards of delayed AI and support early AI. [...]



Triglyceride/HDL ratio and its impact on the risk of diabetes mellitus development during ART

2016-08-22T01:41:10-07:00

Objectives Our primary aim was to study diabetes mellitus (DM) arising during combination ART (cART) and to attempt to identify associations between these cases and triglycerides (TRG) and the TRG to HDL-cholesterol (TRG/HDL) ratio. Our secondary aim was to analyse the association between DM development and hepatic fibrosis. Methods This was a retrospective cohort study. Patients from the Icona Foundation study initiating first-line cART between 1997 and 2013 were selected and observed until new-onset DM or most recent clinical follow-up. The predictive value of TRG and TRG/HDL ratio levels on DM was evaluated using multivariable Poisson regression models. Results Three-thousand, five-hundred and forty-six patients (males, 73.7%; median age, 38 years; median BMI, 23.1 kg/m2; and hepatitis C virus antibody positive, 22.1%) were included. Of these, 80 developed DM over 13 911 person-years of follow-up (PYFU), corresponding to 5.7 cases per 1000 PYFU (95% CI = 4.6–7.1). At multivariable analysis, latest TRG/HDL ratio, when high, was associated with significant increases in DM risk [relative risk (RR) = 1.63; 95% CI = 1.32–2.01 per 10 points higher], while current TRG, in contrast, was associated with new-onset DM only at crude analysis. Advanced liver fibrosis (defined as fibrosis-4 index >3.25) was also shown to be an independent risk factor for DM (RR = 2.91; 95% CI = 1.10–7.72). Conclusions High TRG/HDL ratio predicted risk of new-onset DM, independently of other traditional risk factors. Furthermore, our findings suggest that advanced hepatic fibrosis, estimated using the fibrosis-4 score, could provide an additional predictor for DM. [...]



























Transferable resistance to colistin: a new but old threat

2016-07-21T00:06:04-07:00

In this Leading article, we summarize current knowledge of the occurrence of the first and so far only transferable colistin resistance gene, mcr-1. Its location on a conjugative plasmid is likely to have driven its spread into a range of enteric bacteria in humans and animals. Screening studies have identified mcr-1 in five of the seven continents and retrospective studies in China have identified this gene in Escherichia coli originally isolated in the 1980s, while the first European isolate dates back to 2005. Based on the widespread use of colistin in pigs and poultry in several countries and the higher number of mcr-1-carrying isolates of animal origin than of human origin, it is tempting to assume that this resistance may have emerged in the animal sector. Whatever its origin, interventions to reduce its further spread will require an integrated global one-health approach, comprising robust antibiotic stewardship to reduce unnecessary colistin use, improved infection prevention, and control and surveillance of colistin usage and resistance in both veterinary and human medicine.




Bacteriophage therapy: a regulatory perspective

2016-07-21T00:06:04-07:00

Despite the recognized problem of antibiotic multidrug resistance, very few antibacterial agents with new mechanisms of action are under development. Bacteriophage therapy could offer one alternative strategy to mitigate this challenge. Although widely used throughout the 20th century in Eastern Europe and the former Soviet Union, this potential therapy has not yet been investigated according to rigorous scientific standards. This paper reports on a multistakeholder meeting held at the EMA, which outlined the existing regulatory framework to which such therapy should adhere and reviewed the current obstacles and shortcomings in scientific development for bacteriophage therapy.




New therapeutic strategies for invasive aspergillosis in the era of azole resistance: how should the prevalence of azole resistance be defined?

2016-07-21T00:06:04-07:00

Given reports showing a high prevalence of azole resistance in Aspergillus fumigatus, alternatives to azole therapy are discussed when a threshold of 10% of azole-resistant environmental isolates is reached. This raises the issue of calculation of this threshold, either on the prevalence of azole-resistant isolates as a whole or on the prevalence of azole-resistant cases in populations at risk of invasive aspergillosis (IA). For isolate evaluation, there are high disparities in routine microbiological procedures for the isolation of A. fumigatus and azole resistance detection. There are also huge differences between the microbiological work-up for diagnosing IA. Some centres rely on galactomannan detection alone without actively trying to culture appropriate samples, which affects reliability of the figures on the prevalence of resistance and thus the threshold of resistance. Moreover, reports from the laboratory could mix up figures from completely different patient populations: frequent azole-resistant isolates from pneumology patients and rare azole-resistant isolates from haematology patients. Therefore, to sum isolates from different specimens and different wards can lead to erroneous calculations for the restricted populations at risk of developing IA. In conclusion, assessing the incidence of azole resistance in A. fumigatus should be based on harmonized consensual microbiological methods and reports should be restricted to IA episodes in ide[...]



Azole resistance surveillance in Aspergillus fumigatus: beneficial or biased?

2016-07-21T00:06:04-07:00

Azole resistance is a growing concern with Aspergillus fumigatus, and may cause increased mortality in patients with azole-resistant invasive aspergillosis (IA). Microbial surveillance has been recognized as a fundamental component of resistance management. Surveillance information may be used to inform decisions regarding health services and research funding allocation, to guide local infection control in hospitals and communities, and to direct local and national drug policies and guidelines. Azole resistance frequencies have been based on screening of unselected A. fumigatus isolates, on the number of azole-resistant cases within a cohort of patients with a specific Aspergillus disease, or on analysis of patients within a specific risk group. The various surveillance approaches differ in their aims, as well as in their associated advantages and drawbacks. Nevertheless, a wide range of azole resistance frequencies has been reported, partly due to the denominator used. As most azole resistance is believed to develop in the environment and, as a consequence, azole-naive patients may present with azole-resistant aspergillosis, experts recommended a 10% resistance frequency threshold above which the standard treatment choice, i.e. voriconazole, should be reconsidered. We believe that local resistance rates based on Aspergillus disease and/or risk group should be leading for decisions regarding empirical antifungal therapy in[...]



Polymorphic substitution E157Q in HIV-1 integrase increases R263K-mediated dolutegravir resistance and decreases DNA binding activity

2016-07-21T00:06:04-07:00

Objectives The E157Q substitution in HIV-1 integrase (IN) is a relatively common natural polymorphism associated with HIV resistance to IN strand transfer inhibitors (INSTIs). Although R263K is the most common resistance substitution for the INSTI dolutegravir, an INSTI treatment-experienced individual recently failed dolutegravir-based therapy, with E157Q being the only resistance-associated change reported. Given that different resistance pathways can sometimes synergize to confer high levels of resistance to antiretroviral drugs, we studied the effects of E157Q in association with R263K. Because Glu157 is thought to lie within the binding site of HIV IN DNA binding inhibitors such as FZ41, we also evaluated DNA binding activity and resistance to IN inhibitors in the presence of E157Q. Methods Purified recombinant IN proteins were assessed in cell-free assays for their strand transfer and DNA binding activities. NL4.3 viral stocks harbouring IN mutations were generated and characterized in the presence and absence of IN inhibitors in tissue culture. Results E157Q alone had little if any effect on the biochemical activity of IN, and partially restored the activity of R263K-containing IN. The E157Q/R263K double viral mutant displayed infectiousness in culture equivalent to WT, while increasing resistance to dolutegravir by 10-fold compared with lower-level resistance associated with R263K alon[...]



Pharmacodynamics of anti-HIV gene therapy using viral vectors and targeted endonucleases

2016-07-21T00:06:04-07:00

Objectives A promising curative approach for HIV is to use designer endonucleases that bind and cleave specific target sequences within latent genomes, resulting in mutations that render the virus replication incompetent. We developed a mathematical model to describe the expression and activity of endonucleases delivered to HIV-infected cells using engineered viral vectors in order to guide dose selection and predict therapeutic outcomes. Methods We developed a mechanistic model that predicts the number of transgene copies expressed at a given dose in individual target cells from fluorescence of a reporter gene. We fitted the model to flow cytometry datasets to determine the optimal vector serotype, promoter and dose required to achieve maximum expression. Results We showed that our model provides a more accurate measure of transduction efficiency compared with gating-based methods, which underestimate the percentage of cells expressing reporter genes. We identified that gene expression follows a sigmoid dose–response relationship and that the level of gene expression saturation depends on vector serotype and promoter. We also demonstrated that significant bottlenecks exist at the level of viral uptake and gene expression: only ~1 in 220 added vectors enter a cell and, of these, depending on the dose and promoter used, between 1 in 15 and 1 in 1500 express tran[...]