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Preview: Journal of Antimicrobial Chemotherapy - current issue

Journal of Antimicrobial Chemotherapy Current Issue





Published: Mon, 13 Feb 2017 00:00:00 GMT

Last Build Date: Fri, 17 Mar 2017 08:46:18 GMT

 



Changing epidemiology of candidaemia in Australia

2017-02-13

J Antimicrob Chemother 2017; 72: 1103–8






Therapeutic drug monitoring and use of an adjusted body weight strategy for high-dose voriconazole therapy

2017-01-20

Objectives: A high-dose 12 mg/kg/day (6 mg/kg twice daily) voriconazole regimen was recommended by the CDC to treat patients injected with contaminated methylprednisolone acetate that caused a multi-state fungal outbreak in 2012–13. Therapeutic drug monitoring results of this unique regimen are unknown, as is the most appropriate dosing weight for obese patients. We evaluated voriconazole trough measurements for this dosing scheme, as well as the use of adjusted body weight dosing for obese patients.Methods: Voriconazole trough levels were analysed in obese (BMI ≥35 kg/m2) and non-obese (BMI <35 kg/m2) patients who were given initial therapy with 12 mg/kg/day.Results: Of 138 patients, the first steady-state voriconazole troughs were supratherapeutic (>5 mg/L) in 65 (47%) patients, therapeutic (2–5 mg/L) in 57 (41%) patients and subtherapeutic (<2 mg/L) in 16 (12%) patients. Twenty-three patients had pre-steady-state dose decreases due to supratherapeutic levels, with subsequent first steady-state troughs in the therapeutic (n =17) and subtherapeutic (n =6) categories. Voriconazole doses >11 and >8 mg/kg/day produced mainly first steady-state supratherapeutic troughs in 44 obese and 94 non-obese patients, respectively. An initial 12 mg/kg/day was progressively lowered to a median maintenance dose of 8.5 mg/kg/day in the obese and 8.6 mg/kg/day in the non-obese.Conclusions: A high-dose voriconazole regimen produced initial supratherapeutic troughs that required dose adjustment downward by nearly 30%. Adjusted body weight dosing in obese patients resulted in a similar maintenance dose to total body weight dosing in the non-obese, and appears to be a sensible dosing strategy for these patients.



Anti-TB drug concentrations and drug-associated toxicities among TB/HIV-coinfected patients

2017-01-19

Background: Toxicities due to anti-TB treatment frequently occur among TB/HIV-coinfected patients.Objectives: To determine the association between anti-TB drug concentrations and the occurrence of hepatotoxicity and peripheral neuropathy among TB/HIV-coinfected patients.Methods: TB/HIV-coinfected patients were started on standard dose anti-TB treatment according to WHO guidelines. Anti-TB drug concentrations were measured using HPLC 1, 2 and 4 h after drug intake at 2, 8 and 24 weeks following initiation of TB treatment. Participants were assessed for hepatotoxicity using Division of AIDS toxicity tables and for peripheral neuropathy using clinical assessment of tendon reflexes, vibration sensation or symptoms. Cox regression was used to determine the association between toxicities and drug concentrations.Results: Of the 268 patients enrolled, 58% were male with a median age of 34 years. Participants with no hepatotoxicity or mild, moderate and severe hepatotoxicity had a median Cmax of 6.57 (IQR 4.83–9.41) μg/mL, 7.39 (IQR 5.10–10.20) μg/mL, 7.00 (IQR 6.05–10.95) μg/mL and 3.86 (IQR 2.81–14.24) μg/mL, respectively. There was no difference in the median Cmax of rifampicin among those who had hepatotoxicity and those who did not (P =0.322). There was no difference in the isoniazid median Cmax among those who had peripheral neuropathy 2.34 (1.52–3.23) μg/mL and those who did not 2.21 (1.45–3.11) μg/mL (P =0.49).Conclusions: There was no association between rifampicin concentrations and hepatotoxicity or isoniazid concentrations and peripheral neuropathy among TB/HIV-coinfected patients.



Treatment simplification to atazanavir/ritonavir   +   lamivudine versus maintenance of atazanavir/ritonavir   +   two NRTIs in virologically suppressed HIV-1-infected patients: 48 week results from a randomized trial (ATLAS-M)

2017-01-15

Background: Combination ART (cART)-related toxicities and costs have prompted the need for treatment simplification. The ATLAS-M trial explored 48 week non-inferior efficacy of simplification to atazanavir/ritonavir  +  lamivudine versus maintaining three-drug atazanavir/ritonavir-based cART in virologically suppressed patients.Methods: We performed an open-label, multicentre, randomized, non-inferiority study, enrolling HIV-infected adults on atazanavir/ritonavir + two NRTIs, with stable HIV-RNA <50 copies/mL and CD4 + >200 cells/mm3. Main exclusion criteria were hepatitis B virus coinfection, past virological failure on or resistance to study drugs, recent AIDS and pregnancy. Patients were randomly assigned 1:1 to either switch to 300 mg of atazanavir/100 mg of ritonavir once daily and 300 mg of lamivudine once daily (atazanavir/ritonavir + lamivudine arm) or to continue the previous regimen (atazanavir/ritonavir + two NRTIs arm). The primary study outcome was the maintenance of HIV-RNA <50 copies/mL at week 48 of the ITT-exposed (ITT-e) analysis with switch = failure. The non-inferiority margin was 12%. This study is registered at ClinicalTrials.gov, number NCT01599364.Results: Between July 2011 and June 2014, 266 patients were randomized (133 to each arm). After 48 weeks, the primary study outcome was met by 119 of 133 patients (89.5%) in the atazanavir/ritonavir + lamivudine arm and 106 of 133 patients (79.7%) in the atazanavir/ritonavir + two NRTIs arm [difference atazanavir/ritonavir + lamivudine versus atazanavir/ritonavir + two NRTIs arm: +9.8% (95% CI + 1.2 to + 18.4)], demonstrating non-inferiority and superior efficacy of the atazanavir/ritonavir + lamivudine arm. Virological failure occurred in two (1.5%) patients in the atazanavir/ritonavir + lamivudine arm and six (4.5%) patients in the atazanavir/ritonavir + two NRTIs arm, without resistance selection. A similar proportion of adverse events occurred in both arms.Conclusions: Treatment simplification to atazanavir/ritonavir + lamivudine showed non-inferior efficacy (superiority on post-hoc analysis) and a comparable safety profile over continuing atazanavir/ritonavir + two NRTIs in virologically suppressed patients.



Staphylococcus aureus CC395 harbours a novel composite staphylococcal cassette chromosome mec element

2017-01-14

Background: CoNS species are likely reservoirs of the staphylococcal cassette chromosome mec (SCCmec) in Staphylococcus aureus. S. aureus CC395 is unique as it is capable of exchanging DNA with CoNS via bacteriophages, which are also known to mediate transfer of SCCmec.Objectives: To analyse the structure and putative origin of the SCCmec element in S. aureus CC395.Methods: The only MRSA CC395 strain described in the literature, JS395, was subjected to WGS, and its SCCmec element was compared with those found in CoNS species and other S. aureus strains.Results: JS395 was found to carry an unusually large 88 kb composite SCCmec element. The 33 kb region downstream of orfX harboured a type V SCCmec element and a CRISPR locus, which was most similar to those found in the CoNS species Staphylococcus capitis and Staphylococcus schleiferi. A 55 kb SCC element was identified downstream of the type V SCCmec element and contained a mercury resistance region found in the composite SCC element of some Staphylococcus epidermidis and S. aureus strains, an integrated S. aureus plasmid containing genes for the detoxification of cadmium and arsenic, and a stretch of genes that was partially similar to the type IVg SCCmec element found in a bovine S. aureus strain.Conclusions: The size and complexity of the SCCmec element support the idea that CC395 is highly prone to DNA uptake from CoNS. Thus CC395 may serve as an entry point for SCCmec and SCC structures into S. aureus.






Emergence of Klebsiella variicola positive for NDM-9, a variant of New Delhi metallo-β-lactamase, in an urban river in South Korea

2017-01-12

Objectives: To examine the presence of pathogenic bacteria carrying New Delhi metallo-β-lactamase in the environment and to characterize the genome structures of these strains.Methods: Phenotypic screening of antimicrobial susceptibility and WGS were conducted on three Klebsiella variicola strains possessing NDM-9 isolated from an urban river.Results: Three carbapenem-resistant K. variicola isolated from Gwangju tributary were found to possess blaNDM-9 genes. Antimicrobial susceptibility testing indicated resistance of these strains to aminoglycosides, carbapenems, cephems, folate pathway inhibitors, fosfomycin and penicillins, but susceptibility to fluoroquinolones, phenicols, tetracyclines and miscellaneous agents. WGS revealed that the 108 kb IncFII(Y)-like plasmids carry blaNDM-9 sandwiched between IS15 for the GJ1 strain, IS26 for the GJ2 strain, IS15D1 for the GJ3 strain and ISVsa3, and further bracketed by IS26 and TnAS3 along with the mercury resistance operon upstream and the class 1 integron composed of gene cassettes of aadA2, dfrA12 and sul1 downstream. An aph(3′)-Ia gene conferring resistance to aminoglycosides is located after the integrons. Chromosomally encoded blaLEN-13, fosA, aqxA and oqxB genes, as well as plasmid-mediated blaTEM-1B and blaCTX-M-65 encoding ESBL, ant(3′)-Ia and mph(A) genes, were also identified.Conclusions: The findings of the present study provide us with the information that NDM-9 has been spreading into the environment. Dissemination of NDM-9 in the environment has raised a health risk alarm as this variant of NDM carries MDR genes with highly transferable mobile genetic elements, increasing the possibility of resistance gene transfer among microorganisms in the environment.



Variants of AbGRI3 carrying the armA gene in extensively antibiotic-resistant Acinetobacter baumannii from Singapore

2017-01-10

Objectives: To investigate the context of the ribosomal RNA methyltransferase gene armA in carbapenem-resistant global clone 2 (GC2) Acinetobacter baumannii isolates from Singapore.Methods: Antibiotic resistance was determined using disc diffusion; PCR was used to identify resistance genes. Whole genome sequences were determined and contigs were assembled and ordered using PCR. Resistance regions in unsequenced isolates were mapped.Results: Fifteen GC2 A. baumannii isolated at Singapore General Hospital over the period 2004–11 and found to carry the armA gene were resistant to carbapenems, third-generation cephalosporins, fluoroquinolones and most aminoglycosides. In these isolates, the armA gene was located in a third chromosomal resistance island, previously designated AbGRI3. In four isolates, armA was in a 19 kb IS26-bounded transposon, designated Tn6180. In three of them, a 2.7 kb transposon carrying the aphA1b gene, designated Tn6179, was found adjacent to and sharing an IS26 with Tn6180. However, in these four isolates a 3.1 kb segment of the adjacent chromosomal DNA has been inverted by an IS26-mediated event. The remaining 11 isolates all contained a derivative of Tn6180 that had lost part of the central segment and only one retained Tn6179. The chromosomal inversion was present in four of these and in seven the deletion extended beyond the inversion into adjacent chromosomal DNA. AbGRI3 forms were found in available GC2 sequences carrying armA.Conclusions: In GC2 A. baumannii, the armA gene is located in various forms of a third genomic resistance island named AbGRI3. An aphA1b transposon is variably present in AbGRI3.



Population structure of Japanese extraintestinal pathogenic Escherichia coli and its relationship with antimicrobial resistance

2017-01-10

Objectives: To define the population structure of extraintestinal pathogenic Escherichia coli (ExPEC) in Japan and its relationship with antimicrobial resistance and the major resistance mechanisms for fluoroquinolones and β-lactams, we designed a multicentre prospective study.Methods: A total of 329 ExPEC isolates were collected at 10 Japanese acute-care hospitals during December 2014. We defined the clonal groups of ExPEC by fumC and fimH sequencing (CH typing). Antimicrobial susceptibility testing of 18 agents and the detection of mutations in quinolone resistance-determining regions (QRDRs) and β-lactamases were performed.Results: Among the study isolates, 103 CH types were found, and CH40-30 (25%) and another 10 CH types (35% in total) constituted the major ExPEC population. Ciprofloxacin non-susceptibility, ESBLs and MDR phenotypes were found in 34%, 22% and 33%, respectively. CH40-30, corresponding to the C/H30 clade of the global pandemic ST131 clone, was associated with four QRDR mutations (100%) and blaCTX-M (60%) and was the most frequent type in 15 antimicrobial-non-susceptible populations (dominating 39%–75% of each population, the highest prevalence for ciprofloxacin), the ESBL producers (70%) and the MDR isolates (59%). Isolates that were non-susceptible to nalidixic acid and low-level resistant to ciprofloxacin with one or two QRDR mutations represented 16% of the study isolates and were distributed among the eight major and non-major CH types.Conclusions: More than half of the ExPEC population in Japan consisted of 11 major clones. Of these clones, the CH40-30–ST131-C/H30 clone was the predominant antimicrobial-resistant population. The presence of major clones with low-level ciprofloxacin resistance supports the potential future success of a non-ST131 fluoroquinolone-resistant clone.



Spread of mcr-1 -carrying Enterobacteriaceae in sewage water from Spain

2017-01-10

Objectives: The mobile colistin resistance gene mcr-1 has been identified worldwide in human and animal sources, while its occurrence in the environment is still largely unknown. The aim of this study was to investigate the presence of mcr-1-harbouring Enterobacteriaceae in water samples obtained from rivers and waste water treatment plants in the area of Barcelona, Spain.Methods: The presence of mcr-1 was detected by PCR. Bacterial identification was performed via MALDI-TOF MS. Resistance to colistin was determined by a broth dilution method. The epidemiological relationship between the positive isolates was assessed with PFGE and ST was determined by MLST. Plasmid characterization was performed by transformation experiments, antimicrobial susceptibility testing and incompatibility group PCR.Results: Thirty MDR isolates bearing mcr-1, 29 Escherichia coli (ST632 and ST479) and 1 Klebsiella pneumoniae (ST526), were identified in sewage from two different waste water treatment plants, whereas the gene was not found in river water. All isolates, including the K. pneumoniae, harboured blaCTX-M-55 and blaTEM-1. mcr-1 was in all cases associated with an IncI2 plasmid, which only conferred resistance to colistin. mcr-1 was harboured by two predominant E. coli clones that were found in both waste water treatment plants.Conclusions: This study showed a high occurrence of mcr-1 in the sewage of Barcelona, mainly due to the dissemination of two E. coli pulsotypes that are circulating in the population. The presence of mcr-1 in the environment is a cause for concern, and suggests high prevalence of mcr-1 in the community.



Characterization of carbapenemase-producing Enterobacteriaceae in the West Midlands region of England: 2007–14

2017-01-10

Objectives: Carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly reported in the UK since 2003. We analysed patient and isolate data for CPE confirmed by the national reference laboratory from laboratories in the West Midlands region from November 2007 to December 2014.Methods: MICs were determined by BSAC agar dilution methodology and isolates exhibiting resistance to one or more carbapenems were screened for carbapenemase genes by PCR. Plasmid analyses were performed after electro-transformation of carbapenemase-encoding plasmids. WGS was performed on both transformants and clinical isolates. Patient data provided by the sending laboratories were reviewed.Results: During the study period, CPE (n = 139) were submitted from 13 laboratories in the West Midlands region, originating from 108 patients and including one environmental isolate. CPE submissions increased significantly from 2009 onwards. Isolates were predominantly Klebsiella pneumoniae (89/139) obtained from inpatients. WGS was performed on all clinical isolates and transformants. After deduplication 119 isolates and 96 transformants remained for analysis. Within these, four families of carbapenemase genes were identified: blaNDM (69/119), blaKPC (26/119), blaOXA-48-like (16/119) and blaVIM (7/119); one isolate carried both blaNDM and blaOXA-48-like. Isolates represented diverse STs and plasmid replicon types. Plasmid analyses identified plasmids of different replicon types encoding blaKPC, blaNDM and blaOXA-48-like genes, found across several species and STs.Conclusions: CPE have been reported increasingly in the West Midlands region over a 7 year period. blaNDM, blaKPC and blaOXA-48-like were the dominant carbapenemase genes and were found in a range of diverse genomic/plasmid environments, highlighting their ability to mobilize across different plasmids, often impeding the detection of outbreaks.



Potentiation of ceftazidime by avibactam against β-lactam-resistant Pseudomonas aeruginosa in an in vitro infection model

2017-01-10

Objectives: This study evaluated the in vitro pharmacodynamics of combinations of ceftazidime and the non-β-lactam β-lactamase inhibitor, avibactam, against ceftazidime-, piperacillin/tazobactam- and meropenem-multiresistant Pseudomonas aeruginosa by a quantitative time–kill method.Methods: MICs of ceftazidime plus 0–16 mg/L avibactam were determined against eight isolates of P. aeruginosa. Single-compartment, 24 h time–kill kinetics were investigated for three isolates at 0–16 mg/L avibactam with ceftazidime at 0.25–4-fold the MIC as measured at the respective avibactam concentration. Ceftazidime and avibactam concentrations were measured by LC-MS/MS during the time–kill kinetic studies to evaluate drug degradation.Results: Avibactam alone displayed no antimicrobial activity. MICs of ceftazidime decreased by 8–16-fold in the presence of avibactam at 4 mg/L. The changes in log10 cfu/mL at both the 10 h and 24 h timepoints (versus 0 h) revealed bacterial killing at ≥1-fold MIC. Significantly higher concentrations of ceftazidime alone, as compared with those of ceftazidime in combination, were required to produce any given kill. Without avibactam, ceftazidime degradation was significant (defined as degradation t1/2 <24 h), with as little as 19%±18% of the original concentration remaining at 8 h for the most resistant strain. In combination with avibactam, ceftazidime degradation at ≥ 1-fold MIC was negligible.Conclusion: The addition of avibactam protected ceftazidime from degradation in a dose-dependent manner and restored its cidal and static activity at concentrations in combination well below the MIC of ceftazidime alone.



Impact of long-term care facility residence on the antibiotic resistance of urinary tract Escherichia coli and Klebsiella

2017-01-10

Background: Long-term care facilities (LTCFs) are thought to be important reservoirs of antimicrobial-resistant (AMR) bacteria; however, there is no routine surveillance of resistance in LTCF residents, or large population-based studies comparing AMR in LTCFs with the community, so the relative burden of AMR in LTCFs remains unknown.Objectives: To compare the frequency of antibiotic resistance of urinary tract bacteria from residents of LTCFs for the elderly and adults aged 70 years or older living in the community.Methods: Positive urine specimens reported to any diagnostic microbiology laboratory in the West Midlands region (England) from 1 April 2010 to 31 March 2014 collected from individuals aged 70 years or older were analysed. The resistance of Escherichia coli and Klebsiella to trimethoprim, nitrofurantoin, third-generation cephalosporins and ciprofloxacin and the rate of laboratory-confirmed E. coli and Klebsiella urinary tract infection (UTI) were assessed in LTCF residents and in the community.Results: LTCF residents had a laboratory-confirmed E. coli and Klebsiella UTI rate of 21 per 100 person years compared with 8 per 100 person years in the elderly living in the community [rate ratio (RR)=2.66, 95% CI = 2.58–2.73] and a higher rate of developing E. coli and Klebsiella UTIs caused by bacteria resistant to trimethoprim (RR = 4.41, 95% CI = 4.25–4.57), nitrofurantoin (RR = 4.38, 95% CI = 3.98–4.83), ciprofloxacin (RR = 5.18, 95% CI = 4.82–5.57) and third-generation cephalosporins (RR = 4.49, 95% CI = 4.08–4.94).Conclusions: Residents of LTCFs for the elderly had more than double the rate of E. coli and Klebsiella UTI and more than four times the rate of E. coli and Klebsiella UTI caused by antibiotic-resistant bacteria compared with those living in the community.



Extended stability of antimicrobial agents in administration devices

2017-01-10

Background: Outpatient parenteral antimicrobial therapy (OPAT) is an established approach to patient care. A lack of data on antimicrobial stability within administration devices is a barrier to service expansion, and poses an antimicrobial stewardship dilemma. Often broad-spectrum, long half-life agents are used instead of narrow-spectrum agents, which need more frequent administration, but could possibly be used if stability data were available.Objectives: To complete a comprehensive literature review of published antimicrobial stability data, and assess these against a nationally recognized minimum dataset for medicines compounded into administration devices.Methods: Medline, EMBASE, Global Health, International Pharmaceutical Abstracts and Biomedical Research Database were interrogated in April 2014 and updated in November 2015.Results: A total of 420 citations were reviewed with 121 selected for full text review. None of these papers met the inclusion criteria stipulated in the national standards. The most frequent reason for study exclusion was the tolerance limit for the level of the active pharmaceutical ingredient being wider than 95%–105% and absence of ‘in-use’ testing at 37 °C.Conclusions: This review found no published studies that comply with UK national standards for stability testing. We recommend further research and publication of antimicrobial stability data to support OPAT within the antimicrobial stewardship agenda.



Outpatient parenteral antibiotic therapy (OPAT) in Asia: missing an opportunity

2017-01-10

Objectives: Healthcare facilities internationally have grown outpatient parenteral antibiotic administration services for the last few decades. The literature contains publications from dozens of countries describing systematized processes with specialist oversight and their levels of service provision and outcomes. Such descriptions are absent in the majority of Asian countries. We sought to elucidate the extent and nature of outpatient parenteral antibiotic therapy (OPAT) in Asia and to consider the ramifications and opportunities for improvementMethods: Utilizing colleagues and their personal networks, we surveyed healthcare facilities across 17 countries in Asia to ascertain the current means (if any) of providing OPAT. In that survey we also sought to explore the capacity and interest of these facilities in developing systematized OPAT services.Results: Responses were received from 171 different healthcare facilities from 17 countries. Most (97/171, 57%) stated that they administer outpatient parenteral antibiotics, but only 5 of 162 facilities (3%) outside of Singapore described comprehensive services with specialist oversight.Conclusions: There is very likely a large unrecognized problem of unchecked outpatient parenteral antibiotic administration in Asia. Developing comprehensive and systematized OPAT in Asia is needed as a priority in an environment in which the infectious diseases community is demanding broad stewardship approaches. There are nonetheless challenges in establishing and sustaining OPAT programmes. Local champions and leverage off identified local incentives and needs are key to regional advancement.



Estimated generic prices for novel treatments for drug-resistant tuberculosis

2017-01-10

Background: The estimated worldwide annual incidence of MDR-TB is 480 000, representing 5% of TB incidence, but 20% of mortality. Multiple drugs have recently been developed or repurposed for the treatment of MDR-TB. Currently, treatment for MDR-TB costs thousands of dollars per course.Objectives: To estimate generic prices for novel TB drugs that would be achievable given large-scale competitive manufacture.Methods: Prices for linezolid, moxifloxacin and clofazimine were estimated based on per-kilogram prices of the active pharmaceutical ingredient (API). Other costs were added, including formulation, packaging and a profit margin. The projected costs for sutezolid were estimated to be equivalent to those for linezolid, based on chemical similarity. Generic prices for bedaquiline, delamanid and pretomanid were estimated by assessing routes of synthesis, costs/kg of chemical reagents, routes of synthesis and per-step yields. Costing algorithms reflected variable regulatory requirements and efficiency of scale based on demand, and were validated by testing predictive ability against widely available TB medicines.Results: Estimated generic prices were US$8–$17/month for bedaquiline, $5–$16/month for delamanid, $11–$34/month for pretomanid, $4–$9/month for linezolid, $4–$9/month for sutezolid, $4–$11/month for clofazimine and $4–$8/month for moxifloxacin. The estimated generic prices were 87%–94% lower than the current lowest available prices for bedaquiline, 95%–98% for delamanid and 94%–97% for linezolid. Estimated generic prices were $168–$395 per course for the STREAM trial modified Bangladesh regimens (current costs $734–$1799), $53–$276 for pretomanid-based three-drug regimens and $238–$507 for a delamanid-based four-drug regimen.Conclusions: Competitive large-scale generic manufacture could allow supplies of treatment for 5–10 times more MDR-TB cases within current procurement budgets.



Antimicrobial resistance in Staphylococcus pseudintermedius and the molecular epidemiology of methicillin-resistant S. pseudintermedius in small animals in Finland

2017-01-08

Objectives: To investigate antimicrobial susceptibility in Staphylococcus pseudintermedius and the occurrence of methicillin-resistant S. pseudintermedius (MRSP), to explore the molecular structure of the MRSP population and to analyse risk factors for MRSP.Methods: Susceptibility data for clinical S. pseudintermedius isolates in 2011–15 were analysed using WHONET. All MRSP isolates in 2010–14 (n =362) were typed using PFGE. Representative isolates (n =87) of clusters were analysed using MLST and staphylococcal cassette chromosome mec (SCCmec) typing. Risk factors were analysed using logistic regression.Results: Of the clinical S. pseudintermedius (n =1958; 98% from dogs), 14% were MRSP. Resistance to other antimicrobials varied between 12% and 39%. No trends were observed over time. Among clinical specimens (from infection sites) and screening specimens (from potential carriers), respectively, 2.5% (267/10 813) and 9% (211/2434) revealed MRSP. MLST revealed 42 different STs, including 19 new ones. Clonal complexes 71, 45 and 258 were the most common, but the MRSP population diversified over the years. A clinical S. pseudintermedius isolate was more likely to be MRSP if the patient was on antimicrobials at the time of sampling or was male. The presence of MRSP in screening specimens was more likely if the patient was on multiple antimicrobials at the time of sampling. Specimens from private clinics (versus the Veterinary Teaching Hospital of the University of Helsinki) had a higher likelihood of MRSP in both analyses.Conclusions: Resistance to antimicrobials among S. pseudintermedius in Finland is high, emphasizing the importance of infection control measures and susceptibility testing prior to therapy. The diverse MRSP population indicates non-clonal spread.



Genetic and biochemical characterization of HMB-1, a novel subclass B1 metallo-β-lactamase found in a Pseudomonas aeruginosa clinical isolate

2017-01-08

Objectives: To characterize a novel subclass B1 metallo-β-lactamase (MBL) found in an MDR Pseudomonas aeruginosa clinical isolate.Methods: The isolate P. aeruginosa NRZ-03096 was recovered in 2012 from an anal swab from a patient hospitalized in Northern Germany and showed high MICs of carbapenems. MBL production was analysed by several phenotypic tests. Genetic characterization of the novel bla gene and MLST was performed by WGS. The novel bla gene was expressed in Escherichia coli TOP10 and the enzyme was subjected to biochemical characterization to determine the kinetic parameters Km and kcat.Results:P. aeruginosa NRZ-03096 was resistant to all tested β-lactams and showed an MBL phenotype. Shotgun cloning experiments yielded a clone producing a novel subclass B1 enzyme with only 74.3% identity to the next nearest relative, KHM-1. The novel MBL was named HMB-1 (for Hamburg MBL). Analysis of WGS data showed that the blaHMB-1 gene was chromosomally located as part of a Tn3 family transposon that was named Tn6345. Expression of blaHMB-1 in E. coli TOP10 led to increased resistance to β-lactams. Determination of Km and kcat revealed that HMB-1 had different hydrolytic characteristics compared with KHM-1, with lower hydrolytic rates for cephalosporins and a higher rate for imipenem.Conclusions: The identification of HMB-1 further underlines the ongoing spread and diversification of carbapenemases in Gram-negative human pathogens and especially in P. aeruginosa.



Rapid detection of the plasmid-mediated quinolone resistance determinant AAC(6′)-Ib-cr in Enterobacteriaceae by MALDI-TOF MS analysis

2017-01-08

Objectives: Rapid detection of the plasmid-mediated quinolone resistance determinant AAC(6′)-Ib-cr in Enterobacteriaceae by measuring acetyltransferase activity against fluoroquinolones by MALDI-TOF MS analysis.Methods: The presence of the AAC(6′)-Ib-cr enzyme was determined by MS by measuring the acetyltransferase activity of a collection of 81 isogenic Escherichia coli control strains [10 carrying the AAC(6′)-Ib-cr enzyme during exposure to ciprofloxacin, norfloxacin and levofloxacin] and further analysis of 36 clinical isolates [25 carrying the AAC(6′)-Ib-cr enzyme in addition to different combinations of quinolone resistance mechanisms]. The effect of acetylation yields an increase of 43 Da in the mass of ciprofloxacin and norfloxacin, but not of levofloxacin, that can be observed by visual inspection of the mass peaks in the spectra.Results: Based on the characteristic peak pattern for the acetylated and non-acetylated forms of ciprofloxacin and norfloxacin, a clear differentiation between AAC(6′)-Ib-cr-producing isolates and non-AAC(6′)-Ib-cr-producing isolates was detected after an incubation time of 30 min, both in the isogenic control strains and in the clinical isolates. Levofloxacin was found intact. A 100% agreement was found between the MALDI-TOF-MS-based assay and the results of the molecular characterization of the tested isolates.Conclusions: MALDI-TOF MS is an outstanding method for detection of the AAC(6′)-Ib-cr enzyme in clinical samples. The method is easy to perform and not time consuming, as analytical results can be obtained within minutes. For the first time, MALDI-TOF MS has been used to detect resistance promoted by enzymatic modification of antibiotics aside from β-lactamases, expanding the capacity of analysis into new families of antibiotics.



Impact of obesity on antiretroviral pharmacokinetics and immuno-virological response in HIV-infected patients: a case–control study

2017-01-08

Background: Obesity has high prevalence among HIV-infected patients. Increased adipose tissue mass affects the pharmacokinetics of numerous drugs, but few data are available for antiretroviral drugs.Objectives: In this study we aimed to explore the pharmacokinetics of antiretroviral drugs and the immuno-virological response in obese patients with HIV infection.Patients and methods: We examined data from 2009 to 2012 in our hospital’s database for HIV-1-infected patients who received an antiretroviral drug (abacavir, emtricitabine, lamivudine, tenofovir, efavirenz, etravirine, nevirapine, atazanavir/ritonavir, darunavir/ritonavir, lopinavir/ritonavir or raltegravir). Obese patients were defined as those with BMI ≥30 kg/m2 and normal-weight patients as those with BMI 19–25 kg/m2. Plasma concentrations (C12/24) were compared for each antiretroviral drug using a Mann–Whitney test. Suboptimal dosing and virological outcome were assessed by logistic regression, adjusting on covariates.Results: We enrolled 291 obese and 196 normal-weight patients. Among the 12 analysed antiretroviral drugs, tenofovir, efavirenz and lopinavir C12 values were significantly lower in obese than normal-weight patients: 66 versus 86 ng/mL, 1498 versus 2034 ng/mL and 4595 versus 6420 ng/mL, respectively (P <0.001). Antiretroviral drug C12/24 values were more frequently below efficacy thresholds for obese than for normal-weight patients after adjustment for other covariates (P <0.001). Although obese patients showed a higher CD4 count than normal-weight patients (510 versus 444 cells/mm3, P <0.001), the groups did not differ in virological failure rate.Conclusions: This study highlights the impact of obesity on antiretroviral drug plasma exposure, but identifies no consequence of this suboptimal exposure on the immuno-virological control in this population.



Pan-azole-resistant Candida tropicalis carrying homozygous erg11 mutations at position K143R: a new emerging superbug?

2017-01-08

Objectives: Candidaemia is a public health problem mainly in hospitalized individuals worldwide. In Brazil, Candida albicans is the most prevalent species that causes candidaemia, followed by Candida tropicalis and Candida parapsilosis. Few data on the abundance of antifungal resistance are available for Latin America.Methods: We analysed the frequency of azole and echinocandin resistance in Candida isolates (n =75) collected between 2012 and 2014 at the University Hospital of Federal University of Juiz de Fora (Brazil). The primary targets erg11 (azoles) and fks1 (echinocandins) were sequenced and modelled at the protein level. Antifungal susceptibility testing was performed according to CLSI (M27-A3 and M27-S4) and according to EUCAST.Results: The three most frequent species were C. albicans (38.0%), C. tropicalis (30.0%) and Candida glabrata (17.0%). Azole resistance was observed in 27.0% of all Candida isolates, while 20.0% of all isolates were echinocandin resistant. A novel mutation in erg11 at location K143R was found to be associated with phenotypically pan-azole-resistant C. tropicalis isolates. This mutation maps near the active binding site of erg11 and is likely to confer pan-azole resistance to C. tropicalis.Conclusions: A novel point mutation (K143R) located in the erg11 gene of C. tropicalis was found in pan-azole-resistant strains. According to our protein homology model, it is very likely that the mutation K143R causes pan-azole resistance in C. tropicalis. Moreover, an up-regulation of ABC transporters was observed, which can add up to a pan-azole-resistant phenotype.



Sale of antibiotics without a prescription at community pharmacies in urban China: a multicentre cross-sectional survey

2017-01-06

Objectives: To quantify sales of antibiotics without a medical prescription and to assess the quality of pharmacy services in relation to the antibiotics sold in community pharmacies in urban China.Methods: A multicentre cross-sectional survey of community pharmacies was undertaken in 2015 using the simulated client method. Two clinical case scenarios (paediatric diarrhoea and adult acute upper respiratory infection) were presented at systematically sampled community pharmacies in Eastern (Nanjing), Central (Changsha) and Western China (Xi’an).Results: Of 256 pharmacies, antibiotics were obtained without a prescription from 55.9% (95% CI: 49.5%–62.0%) when paediatric diarrhoea was simulated and from 77.7% (95% CI: 72.1%–82.7%) when adult respiratory infection was simulated. Of the pharmacies where antibiotics were dispensed, 83.9% and 66.3% dispensed after the simulated clients requested or insisted in the case of paediatric diarrhoea and adult respiratory infection, respectively. Significant differences (P < 0.001, χ2 test) in inappropriate antibiotic dispensing were found among cities, with 57.7%, 37.3% and 73.7% in the case of paediatric diarrhoea and 60.8%, 80.7% and 96.1% in adult respiratory infection in Nanjing, Changsha and Xi’an, respectively. Pharmacists were available in only 14.8% (95% CI: 10.7%–19.8%) of the pharmacies. The performance of pharmacy staff regarding the provision of information and advice was unsatisfactory.Conclusions: Antibiotics were easily obtained without a prescription in community pharmacies in urban China. Measures to enhance the enforcement of prescription-only regulations and training programmes for pharmacy staff to promote the appropriate use of antibiotics are warranted.



Genome-wide association study of nevirapine hypersensitivity in a sub-Saharan African HIV-infected population

2017-01-05

Background: The antiretroviral nevirapine is associated with hypersensitivity reactions in 6%–10% of patients, including hepatotoxicity, maculopapular exanthema, Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).Objectives: To undertake a genome-wide association study (GWAS) to identify genetic predisposing factors for the different clinical phenotypes associated with nevirapine hypersensitivity.Methods: A GWAS was undertaken in a discovery cohort of 151 nevirapine-hypersensitive and 182 tolerant, HIV-infected Malawian adults. Replication of signals was determined in a cohort of 116 cases and 68 controls obtained from Malawi, Uganda and Mozambique. Interaction with ERAP genes was determined in patients positive for HLA-C*04:01. In silico docking studies were also performed for HLA-C*04:01.Results: Fifteen SNPs demonstrated nominal significance (P <1 × 10−5) with one or more of the hypersensitivity phenotypes. The most promising signal was seen in SJS/TEN, where rs5010528 (HLA-C locus) approached genome-wide significance (P <8.5 × 10−8) and was below HLA-wide significance (P <2.5 × 10−4) in the meta-analysis of discovery and replication cohorts [OR 4.84 (95% CI 2.71–8.61)]. rs5010528 is a strong proxy for HLA-C*04:01 carriage: in silico docking showed that two residues (33 and 123) in the B pocket were the most likely nevirapine interactors. There was no interaction between HLA-C*04:01 and ERAP1, but there is a potential protective effect with ERAP2 [P =0.019, OR 0.43 (95% CI 0.21–0.87)].Conclusions:HLA-C*04:01 predisposes to nevirapine-induced SJS/TEN in sub-Saharan Africans, but not to other hypersensitivity phenotypes. This is likely to be mediated via binding to the B pocket of the HLA-C peptide. Whether this risk is modulated by ERAP2 variants requires further study.









Inhibition of β-lactamases of mycobacteria by avibactam and clavulanate

2016-12-30

Objectives:Mycobacterium tuberculosis and Mycobacterium abscessus produce broad-spectrum class A β-lactamases, BlaC and BlaMab, which are inhibited by clavulanate and avibactam, respectively. BlaC differs from BlaMab at Ambler position 132 in the conserved motif SDN (SDG versus SDN, respectively). Here, we investigated whether this polymorphism could account for the inhibition specificity of β-lactamases from slowly and rapidly growing mycobacteria.Methods: Enzyme kinetics were determined to assess the impact of the substitutions G132N in BlaC and N132G in BlaMab on β-lactamase inhibition by clavulanate and avibactam. The stability of acylenzymes was evaluated by MS. The impact of the substitutions on the antibacterial activity of drug combinations was determined based on production of the β-lactamases in Escherichia coli.Results: The substitution G132N increased 140-fold the efficacy of BlaC inhibition by avibactam and abolished clavulanate inhibition due to acylenzyme hydrolysis. BlaMab efficiently hydrolysed clavulanate, but the substitution N132G led to a 5600-fold reduction in the hydrolysis rate constant kcat due to stabilization of BlaMab–clavulanate covalent adducts. The N132G substitution also led to a 610-fold reduction in the efficacy of BlaMab carbamylation by avibactam. Testing resistance to the amoxicillin/clavulanate and amoxicillin/avibactam combinations revealed that modifications in the catalytic properties of the β-lactamases resulted in opposite shifts from susceptibility to resistance and vice versa.Conclusions: G132N and N132G had opposite effects on the inhibition of BlaC and BlaMab, indicating that these substitutions might lead to acquisition of resistance to either of the β-lactamase inhibitors, but not to both of them.



Population-based meta-analysis of roxithromycin pharmacokinetics: dosing implications of saturable absorption and protein binding

2016-12-30

Objectives: The macrolide antibiotic roxithromycin has seen widespread clinical use for several decades; however, no population pharmacokinetic analysis has been published. Early studies indicated saturation of protein binding and absorption at doses within the approved range, which may impact pharmacodynamic target attainment since regimens of 150 mg twice daily and 300 mg once daily are used interchangeably in clinical practice. This study aimed to develop a population-based meta-analysis of roxithromycin pharmacokinetics, and utilize this model to inform optimal dosing regimens.Methods: Following an extensive search, roxithromycin pharmacokinetic data were collected or digitized from literature publications. Population pharmacokinetic modelling was undertaken with ADAPT. Dosing simulations were performed to investigate differences in exposure and pharmacodynamic target attainment between dosing regimens.Results: A two-compartment model with saturable absorption described the data (n =63); changes in free drug exposure were simulated using a saturable protein binding model. Simulations indicated that a 300 mg daily regimen achieves a 37% and 53% lower total or free AUC (fAUC), respectively, compared with 150 mg twice daily. These pharmacokinetic differences translated to significantly lower target attainment (fAUC/MIC ratio >20) with a 300 mg daily regimen at MICs of 0.5 and 1 mg/L (51% and 7%) compared with patients receiving 150 mg twice daily (82% and 54%).Conclusions: Roxithromycin displays saturable absorption and protein binding leading to lower exposure and lower target attainment at MICs ≥0.5 mg/L with widely used once-daily dosing regimens, indicating that twice-daily regimens may be preferable for pathogens less susceptible to roxithromycin.



Qualitative and quantitative HIV antibodies and viral reservoir size characterization in vertically infected children with virological suppression

2016-12-30

Background: Absence of detectable viraemia after treatment cessation in some vertically HIV-infected (VHIV) children suggests that early initiation of HAART could lead to functional cure.Objectives: We described the factors associated with HIV antibody levels and the viral reservoir size in HAART-treated VHIV children.Methods: Study included 97 VHIV children with virological suppression, in Bamako, Mali. The anti-gp41 antibody activities and HIV serostatus were assessed. The viral reservoir size was measured by quantifying total cell-associated HIV DNA.Results: Among the children studied, the median total HIV DNA level was 445 copies/106 cells (IQR = 187–914) and the median anti-gp41 antibody activity was 0.29 OD (IQR = 0.18–0.75). Low activity of anti-gp41 antibodies was associated with a younger age of HAART initiation (P =0.01). Overall, eight HIV-1 seroreversions were identified.Conclusions: Study identified potential candidates with low viral reservoir and low antibody levels or activities for future trials aiming to reduce HIV-1 reservoir to limit HAART duration.



Novel lnu (G) gene conferring resistance to lincomycin by nucleotidylation, located on Tn 6260 from Enterococcus faecalis E531

2016-12-30

Objectives: To identify a novel putative lincosamide resistance gene determinant in a swine Enterococcus faecalis E531 exhibiting a lincosamide resistance/macrolide susceptibility (LRMS) phenotype and to determine its location and genetic environment.Methods: The whole genomic DNA of E. faecalis E531, which tested negative for the known lincosamide nucleotidyltransferase genes, was sequenced. A putative lincosamide resistance gene determinant was cloned into an Escherichia coliE. faecalis shuttle vector (pAM401) and transformed into E. faecalis JH2-2. The MICs were determined by the microbroth dilution method. Inactivity of lincomycin was examined by UPLC-MS/MS. Inverse PCR and primer walking were used to explore the genetic environment based on the assembled sequence.Results: A novel resistance gene, designated lnu(G), which encodes a putative lincosamide nucleotidyltransferase, was found in E. faecalis E531. The deduced Lnu(G) amino acid sequence displayed 76.0% identity to Lnu(B) in Enterococcus faecium. Both E. faecalis E531 and E. faecalis JH2-2 harbouring pAM401-lnu(G) showed a 4-fold increase in the MICs of lincomycin, compared with E. faecalis JH2-2 or E. faecalis JH2-2 harbouring empty vector pAM401 only. UPLC-MS/MS demonstrated that the Lnu(G) enzyme catalysed adenylylation of lincomycin. The genetic environment analysis revealed that the lnu(G) gene was embedded into a novel putative transposon, designated Tn6260, which was active.Conclusions: A novel lincosamide nucleotidyltransferase gene lnu(G) was identified in E. faecalis. The location of the lnu(G) gene on a mobile element Tn6260 makes it easy to disseminate.









Voriconazole MICs are predictive for the outcome of experimental disseminated scedosporiosis

2016-12-24

Background: Scedosporiosis is associated with a mortality rate of up to 90% in patients suffering from disseminated infections. Recommended first-line treatment is voriconazole, but epidemiological cut-off values and clinical breakpoints have not been determined.Objectives: To correlate voriconazole treatment response in mice suffering from disseminated scedosporiosis with MIC values determined using CLSI broth microdilution, Etest (bioMérieux) and disc diffusion.Methods: Voriconazole MICs for 31 Scedosporium apiospermum strains were determined using CLSI broth microdilution, Etest and disc diffusion. Groups of mice were challenged intravenously with 1 out of 16 S. apiospermum strains (voriconazole CLSI broth microdilution MIC range: 0.125–8.0 mg/L) and treated with 40 mg/kg voriconazole orally by gavage once daily. Efficacy of voriconazole was evaluated by a statistically significant (P <0.05) reduction in fungal burden in brain.Results: A categorical agreement of 90.4% was reached for CLSI broth microdilution and disc diffusion and of 93.6% for CLSI broth microdilution and Etest. Correlation of CLSI MICs and in vivo outcome was good, as mice challenged with strains with an MIC ≤2 mg/L responded to voriconazole therapy in 92.3% and those challenged with strains with an MIC ≥4 mg/L responded to voriconazole therapy in 33.3%.Conclusions: CLSI broth microdilution and Etest deliver comparable results that enable a prediction of in vivo outcome. Our results suggest that voriconazole is able to reduce fungal burden in the brain of 92.3% of all mice challenged with strains with voriconazole CLSI MICs ≤2 mg/L, while mice challenged with strains with CLSI MICs ≥4 mg/L showed limited response to voriconazole treatment.



Polyclonal emergence of vanA vancomycin-resistant Enterococcus faecium in Australia

2016-12-24

Objectives: To investigate the genetic context associated with the emergence of vanA VRE in Australia.Methods: The whole genomes of 18 randomly selected vanA-positive Enterococcus faecium patient isolates, collected between 2011 and 2013 from hospitals in four Australian capitals, were sequenced and analysed.Results:In silico typing and transposon/plasmid assembly revealed that the sequenced isolates represented (in most cases) different hospital-adapted STs and were associated with a variety of different Tn1546 variants and plasmid backbone structures.Conclusions: The recent emergence of vanA VRE in Australia was polyclonal and not associated with the dissemination of a single ‘dominant’ ST or vanA-encoding plasmid. Interestingly, the factors contributing to this epidemiological change are not known and future studies may need to consider investigation of potential community sources.



Comparison of phenotypic methods for the detection of penicillinase in Staphylococcus aureus and proposal of a practical diagnostic approach

2016-12-20

Objectives: Disc diffusion is a cost-efficient, low-complexity, reliable method for detection of blaZ-mediated benzylpenicillin resistance in Staphylococcus aureus if the zone edge is inspected. EUCAST breakpoints cannot fully separate β-lactamase-positive from β-lactamase-negative strains, and EUCAST recommends the zone edge test. Literature on nitrocefin-based testing and the zone edge test is scarce with wide variations in reported assay performance.Methods: This study compared two different nitrocefin-based commercial and in-house tests and the EUCAST-based zone edge test for penicillinase detection in S. aureus applying a PCR-based gold standard.Results: In total, 215 non-duplicate clinical S. aureus isolates were included in the study, of which 127 (59.1%) did not harbour a blaZ gene, whereas 88 (40.9%) were blaZ positive. This study showed that for blaZ detection the zone edge test is more sensitive (96.6%) than nitrocefin tests independent of using nitrocefin discs (87.5% sensitivity) or solution (89.8% sensitivity), and that the significant inter-person variations of the zone edge test are probably related to the training level of the individual investigators (individual sensitivity ranging from 68.2% to 96.6%, specificity ranging from 89.8% to 100%).Conclusions: In addition to continued and strict training of investigators, we propose mandatory checking of benzylpenicillin zone edges, particularly in an investigation zone from 26 to 30 mm, which can result in improved specificity/positive predictive value of the zone edge test (from 98.4% to 100%) but retains the high sensitivity/negative predictive value of the method.









WalK(S221P), a naturally occurring mutation, confers vancomycin resistance in VISA strain XN108

2016-12-19

Objectives: Vancomycin-intermediate Staphylococcus aureus (VISA) strains have spread globally. We previously isolated an ST239 VISA (XN108) with a vancomycin MIC of 12 mg/L. The mechanism for XN108 resistance to vancomycin was investigated in this study.Methods: Genome comparison was performed to characterize mutations that might contribute to the XN108 resistance phenotype. The novel mutation WalK(S221P) was identified and investigated using allelic replacement experiments. Vancomycin susceptibilities, autolytic activities and morphologies of the strains were examined. Autophosphorylation activities of WalK and the WalK(S221P) mutant were determined in vitro with [λ-32P]ATP, and binding activity of WalK(S221P)-activated WalR to the promoter region of its target gene lytM was determined by electrophoretic mobility shift assay.Results: Genome comparison revealed three mutations, GraS(T136I), RpoB(H481N) and WalK(S221P), which might be responsible for vancomycin resistance in XN108. The introduction of WalK(S221P) to the vancomycin-susceptible strain N315 increased its vancomycin MIC from 1.5 to 8 mg/L, whereas the allelic replacement of WalK(S221P) with the native N315 WalK allele in XN108 decreased its vancomycin MIC from 12 to 4 mg/L. The VISA strains have thickened cell walls and decreased autolysis, consistent with observed changes in the expression of genes involved in cell wall metabolism and virulence regulation. WalK(S221P) exhibited reduced autophosphorylation, which may lead to reduced phosphorylation of WalR. WalK(S221P)-phosphorylated WalR also exhibited a reduced capacity to bind to the lytM promoter.Conclusions: The naturally occurring WalK(S221P) mutation plays a key role in vancomycin resistance in XN108.



Emergence and dissemination of a linezolid-resistant Staphylococcus capitis clone in Europe

2016-12-19

Objectives: We investigated the epidemiological, clinical, microbiological and genetic characteristics of linezolid-resistant (LZR) Staphylococcus capitis isolates from French ICUs, and compared them with LZR S. capitis isolates from other European countries.Methods: All LZR isolates were subjected to antimicrobial susceptibility testing (AST) and the presence of cfr and optrA genes as well as mutations in the 23S rRNA and ribosomal proteins were investigated using specific PCR with sequencing. The genetic relationship between isolates was investigated using PFGE and WGS. Epidemiological data concerning LZR S. capitis were collected retrospectively in French microbiology laboratories.Results: Twenty-one LZR isolates were studied: 9 from France, 11 from Greece and 1 from Finland. All were resistant to methicillin and aminoglycosides. In addition, this unusual AST profile was identified in S. capitis isolates from seven French hospitals, and represented up to 12% of the S. capitis isolates in one centre. A G2576T mutation in 23S rRNA was identified in all isolates; cfr and optrA genes were absent. All isolates belonged to the same clone on the basis of their PFGE profiles, whatever their geographical origin. WGS found at most 212 SNPs between core genomes of the LZR isolates.Conclusions: We identified and characterized an LZR S. capitis clone disseminated in three European countries, harbouring the same multiple resistance and a G2576T mutation in the 23S rRNA. The possible unrecognized wider distribution of this clone, belonging to a species classically regarded as a low-virulence skin colonizer, is of major concern not least because of the increasing use of oxazolidinones.



Rapid EUCAST disc diffusion testing of MDR Escherichia coli and Klebsiella pneumoniae : inhibition zones for extended-spectrum cephalosporins can be reliably read after 6 h of incubation

2016-12-19

Objectives: The need for rapid antibiotic susceptibility testing increases with escalating levels of antimicrobial resistance in Enterobacteriaceae. Our objective was to evaluate the accuracy of reading EUCAST disc diffusion, ROSCO ESBL and carbapenemase detection kits and the Mast Carbapenemase Activity Test (CAT-ID) disc, after 6 h of incubation.Methods: We used a collection of 128 isolates of Escherichia coli and Klebsiella pneumoniae with a wide variety of resistance mechanisms. Inhibition zones read from digital photo images with the BD Kiestra™ Total Lab Automation System after 6 h of incubation were compared with standard reading, after 18 h, of the same Mueller–Hinton agar plates.Results: For WT isolates, zones were generally smaller at 6 h than at 18 h. Cefotaxime had excellent categorical agreement of 99%, despite the high number of challenge isolates. However, for some other antimicrobials, hetero-resistant subpopulations were commonly invisible at 6 h, which resulted in an unacceptable number of errors when using standard EUCAST breakpoints. Accurate ESBL detection was possible at 6 h for isolates lacking other β-lactamases. Carbapenemase detection was not reliable after 6 h.Conclusions: Inhibition zone reading at 6 h is an accurate method for susceptibility testing of extended-spectrum cephalosporins for Enterobacteriaceae. For other antimicrobials, 6 h reading can be used for preliminary reports of clearly resistant or susceptible isolates, preferably with application of adjusted breakpoints including an area of uncertainty between susceptible and resistant values.



Efficacy and pharmacokinetics of ME1100, a novel optimized formulation of arbekacin for inhalation, compared with amikacin in a murine model of ventilator-associated pneumonia caused by Pseudomonas aeruginosa

2016-12-19

Background: Arbekacin is an aminoglycoside that shows strong antimicrobial activity against Gram-positive bacteria, including MRSA, as well as Pseudomonas aeruginosa. The therapeutic effectiveness of arbekacin is directly related to Cmax at the infection site. To maximize drug delivery to the respiratory tract and minimize the systemic toxicity, arbekacin optimized for inhalation, ME1100, is under development. In this study, we investigated the efficacy and pharmacokinetics of ME1100 in a murine model of ventilator-associated pneumonia caused by P. aeruginosa by using a customized investigational nebulizer system.Methods: The mice were treated for 5 min, once daily, with placebo, 3, 10 or 30 mg/mL ME1100 or 30 mg/mL amikacin.Results: In the survival study, the survival rate was significantly improved in the 10 and 30 mg/mL ME1100 treatment groups compared with that in the placebo group. The number of bacteria in the lungs was significantly lower in the 30 mg/mL ME1100 treatment group at 6 h after the initial treatment, compared with all other groups. In the pharmacokinetic study, the Cmax in the 30 mg/mL ME1100 treatment group in the epithelial lining fluid (ELF) and plasma was 31.1 and 1.2 mg/L, respectively. Furthermore, we compared the efficacy of ME1100 with that of amikacin. Although there were no significant differences in ELF and plasma concentrations between 30 mg/mL of ME1100 and 30 mg/mL of amikacin, ME1100 significantly improved the survival rate compared with amikacin.Conclusions: The results of our study demonstrated the in vivo effectiveness of ME1100 and its superiority to amikacin.



Cumulative and temporal associations between antimicrobial prescribing and community-associated Clostridium difficile infection: population-based case–control study using administrative data

2016-12-19

Background: Community-associated Clostridium difficile infection (CA-CDI; defined as cases without prior hospitalization in the previous 12 weeks who were either tested outside of hospital or tested within 2 days of admission to hospital) is a major public health problem. This study estimates the magnitude of the association between temporal and cumulative prescribing of antimicrobials in primary care and CA-CDI.Methods: Three national patient-level datasets, covering CDI cases, community prescriptions and hospitalizations, were linked by the NHS Scotland unique patient identifier, the Community Health Index (CHI). All validated cases of CDI from August 2010 to July 2013 were extracted and up to six population-based controls were matched to each case from the CHI register for Scotland. Statistical analysis used conditional logistic regression.Results: The 1446 unique cases of CA-CDI were linked with 7964 age-, sex- and location-matched controls. Cumulative exposure to any antimicrobial in the previous 6 months has a monotonic dose–response association with CA-CDI. Individuals with more than 28 DDDs to any antimicrobial (19.9% of cases) had an OR of 4.4 (95% CI 3.4–5.6) compared with those unexposed. Individuals exposed to 29+ DDDs of high-risk antimicrobials (cephalosporins, clindamycin, co-amoxiclav or fluoroquinolones) had an OR of 17.9 (95% CI 7.6–42.2). Elevated CA-CDI risk following high-risk antimicrobial exposure was greatest in the first month (OR = 12.5, 95% CI 8.9–17.4), but was still present 4–6 months later (OR = 2.6, 95% CI 1.7–3.9). Cases exposed to 29+ DDDs had prescription patterns more consistent with repeated therapeutic courses, using different antimicrobials, than long-term prophylactic use.Conclusions: This analysis demonstrated temporal and dose–response associations between CA-CDI risk and antimicrobials, with an impact of exposure to high-risk antimicrobials remaining 4–6 months later.



Influence of antimicrobial susceptibility reporting on junior doctors’ decision to prescribe antimicrobials inappropriately

2016-12-19

Objectives: Inappropriate antimicrobial use drives antimicrobial resistance and is a global public health problem. This study examined whether withholding antimicrobial susceptibilities in combination with interpretive comments on microbiological reports influenced the decision to inappropriately prescribe antibiotics in a controlled survey.Methods: Seventy junior doctors attending educational sessions were given one of two surveys describing four clinical case vignettes (scenarios) in which antimicrobial treatment was not indicated. They were asked to select their preferred treatment from multiple choices. In the scenarios labelled ‘A’, the laboratory report did not report antibiotic susceptibilities, but included comments from the microbiologist. In the scenarios labelled ‘B’, the laboratory report included full organism identification and susceptibility results without additional comments.Results: For scenarios 1, 2 and 3 there was a significantly higher probability (P <0.01) that the doctor selected an answer involving antibiotic treatment if he/she received the ‘B’ version of the scenario where reports included antimicrobial susceptibilities, but no interpretive comments. This was significant in both interns and more senior doctors. In scenario 4, of which there were two versions, there was no difference seen in the answers between the groups given scenario A or B.Conclusions: The results of this survey suggest that withholding antimicrobial susceptibility results in combination with interpretive comments on microbiology reports significantly influences the decision of junior doctors to prescribe antibiotics in low-acuity outpatient setting scenarios (represented in scenarios 1–3), but not in inpatient scenarios (represented in scenario 4).



Electronic prescribing system design priorities for antimicrobial stewardship: a cross-sectional survey of 142 UK infection specialists

2016-12-19

Background: The implementation of electronic prescribing and medication administration (EPMA) systems is a priority for hospitals and a potential component of antimicrobial stewardship (AMS).Objectives: To identify software features within EPMA systems that could potentially facilitate AMS and to survey practising UK infection specialist healthcare professionals in order to assign priority to these software features.Methods: A questionnaire was developed using nominal group technique and transmitted via email links through professional networks. The questionnaire collected demographic data, information on priority areas and anticipated impact of EPMA. Responses from different respondent groups were compared using the Mann–Whitney U-test.Results: Responses were received from 164 individuals (142 analysable). Respondents were predominantly specialist infection pharmacists (48%) or medical microbiologists (37%). Of the pharmacists, 59% had experience of EPMA in their hospitals compared with 35% of microbiologists. Pharmacists assigned higher priority to indication prompt (P <0.001), allergy checker (P =0.003), treatment protocols (P =0.003), drug–indication mismatch alerts (P =0.031) and prolonged course alerts (P =0.041) and lower priority to a dose checker for adults (P =0.02) and an interaction checker (P <0.05) than microbiologists. A ‘soft stop’ functionality was rated essential or high priority by 89% of respondents. Potential EPMA software features were expected to have the greatest impact on stewardship, treatment efficacy and patient safety outcomes with lowest impact on Clostridium difficile infection, antimicrobial resistance and drug expenditure.Conclusions: The survey demonstrates key differences in health professionals’ opinions of potential healthcare benefits of EPMA, but a consensus of anticipated positive impa[...]



From guidelines to practice: a pharmacist-driven prospective audit and feedback improvement model for peri-operative antibiotic prophylaxis in 34 South African hospitals

2016-12-19

Background: Few data exist on the implementation of process measures to facilitate adherence to peri-operative antibiotic prophylaxis (PAP) guidelines in Africa.Objectives: To implement an improvement model for PAP utilizing existing resources, in order to achieve a reduction in surgical site infections (SSIs) across a heterogeneous group of 34 urban and rural South African hospitals.Methods: A pharmacist-driven, prospective audit and feedback strategy involving change management and improvement principles was utilized. This 2.5 year intervention involved a pre-implementation phase to test a PAP guideline and a ‘toolkit’ at pilot sites. Following antimicrobial stewardship committee and clinician endorsement, the model was introduced in all institutions and a survey of baseline SSI and compliance rates with four process measures (antibiotic choice, dose, administration time and duration) was performed. The post-implementation phase involved audit, intervention and monthly feedback to facilitate improvements in compliance.Results: For 70 weeks of standardized measurements and feedback, 24 206 surgical cases were reviewed. There was a significant improvement in compliance with all process measures (composite compliance) from 66.8% (95% CI 64.8–68.7) to 83.3% (95% CI 80.8–85.8), representing a 24.7% increase (P <0.0001). The SSI rate decreased by 19.7% from a mean group rate of 2.46 (95% CI 2.18–2.73) pre-intervention to 1.97 post-intervention (95% CI 1.79–2.15) (P =0.0029).Conclusions: The implementation of process improvement initiatives and principles targeted to institutional needs utilizing pharmacists can effectively improve PAP guideline compliance and sustainable patient outcomes.



Improving feedback of surveillance data on antimicrobial consumption, resistance and stewardship in England: putting the data at your Fingertips

2016-12-19

The provision of better access to and use of surveillance data is a key component of the UK 5 Year Antimicrobial Resistance (AMR) Strategy. Since April 2016, PHE has made data on practice (infection prevention and control; antimicrobial stewardship) and outcome (prevalence of AMR, antibiotic use and healthcare-associated infections) available through Fingertips, a publicly accessible web tool (https://fingertips.phe.org.uk/profile/amr-local-indicators). Fingertips provides access to a wide range of public health data presented as thematic profiles, with the above data being available through the ‘AMR local indicators’ profile. Local data on a range of indicators can be viewed at the level of National Health Service acute trusts, Clinical Commissioning Groups or general practitioner practices, all of which can be compared with the corresponding aggregate values for England to allow benchmarking. The data can be viewed in a range of formats including an overview showing counts and rates, interactive maps, spine charts and graphs that show temporal trends over a range of time scales or allow correlations between pairs of indicators. The aim of the AMR local indicators profile on Fingertips is to support the development of local action plans to optimize antibiotic prescribing and reduce AMR and healthcare-associated infections. Provision of access to relevant information in an easy to use format will help local stakeholders, including healthcare staff, commissioners, Directors of Public Health, academics and the public, to benchmark relevant local AMR data and to monitor the impact of local initiatives to tackle AMR over time.



Issues in antifungal stewardship: an opportunity that should not be lost

2016-12-19

Many countries have observed an increase in the incidence of invasive fungal infections (IFIs) over the past two decades with emergence of new risk factors and isolation of new fungal pathogens. Early diagnosis and appropriate antifungal treatment remain the cornerstones of successful outcomes. However, due to non-specific clinical presentations and limited availability of rapid diagnostic tests, in more than half of cases antifungal treatment is inappropriate. As a result, the emergence of antifungal resistance both in yeasts and mycelial fungi is becoming increasingly common. The Delhi Chapter of the Indian Association of Medical Microbiologists (IAMM-DC) organized a 1 day workshop in collaboration with BSAC on 10 December 2015 in New Delhi to design a road map towards the development of a robust antifungal stewardship programme in the context of conditions in India. The workshop aimed at developing a road map for optimizing better outcomes in patients with IFIs while minimizing unintended consequences of antifungal use, ultimately leading to reduced healthcare costs and prevention development of resistance to antifungals. The workshop was a conclave of all stakeholders, eminent experts from India and the UK, including clinical microbiologists, critical care specialists and infectious disease physicians. Various issues in managing IFIs were discussed, including epidemiology, diagnostic and therapeutic algorithms in different healthcare settings. At the end of the deliberations, a consensus opinion and key messages were formulated, outlining a step-by-step approach to tackling the growing incidence of IFIs and antifungal resistance, particularly in the Indian scenario.



Systematic review of public-targeted communication interventions to improve antibiotic use

2016-12-19

Background: Excessive use of antibiotics accelerates the acquisition/spread of antimicrobial resistance. A systematic review was conducted to identify the components of successful communication interventions targeted at the general public to improve antibiotic use.Methods: The databases MEDLINE, EMBASE, CINAHL, Web of Science and Cochrane Library were searched. Search terms were related to the population (public, community), intervention (campaign, mass media) and outcomes (antibiotic, antimicrobial resistance). References were screened for inclusion by one author with a random subset of 10% screened by a second author. No date restrictions were applied and only articles in the English language were considered. Studies had to have a control group or be an interrupted time-series. Outcomes had to measure change in antibiotic-related prescribing/consumption and/or the public’s knowledge, attitudes or behaviour. Two reviewers assessed the quality of studies. Narrative synthesis was performed.Results: Fourteen studies were included with an estimated 74–75 million participants. Most studies were conducted in the United States or Europe and targeted both the general public and clinicians. Twelve of the studies measured changes in antibiotic prescribing. There was quite strong (P < 0·05 to ≥ 0·01) to very strong (P < 0·001) evidence that interventions that targeted prescribing for RTIs were associated with decreases in antibiotic prescribing; the majority of these studies reported reductions of greater than −14% with the largest effect size reaching −30%.Conclusion: Multi-faceted communication interventions that target both the general public and clinicians can reduce antibiotic prescribing in high-income countries but the sustainability of reductions in antibiotic prescribing is unclear.



Public health risk of antimicrobial resistance transfer from companion animals

2016-12-05

Antimicrobials are important tools for the therapy of infectious bacterial diseases in companion animals. Loss of efficacy of antimicrobial substances can seriously compromise animal health and welfare. A need for the development of new antimicrobials for the therapy of multiresistant infections, particularly those caused by Gram-negative bacteria, has been acknowledged in human medicine and a future corresponding need in veterinary medicine is expected. A unique aspect related to antimicrobial resistance and risk of resistance transfer in companion animals is their close contact with humans. This creates opportunities for interspecies transmission of resistant bacteria. Yet, the current knowledge of this field is limited and no risk assessment is performed when approving new veterinary antimicrobials. The objective of this review is to summarize the current knowledge on the use and indications for antimicrobials in companion animals, drug-resistant bacteria of concern among companion animals, risk factors for colonization of companion animals with resistant bacteria and transmission of antimicrobial resistance (bacteria and/or resistance determinants) between animals and humans. The major antimicrobial resistance microbiological hazards originating from companion animals that directly or indirectly may cause adverse health effects in humans are MRSA, methicillin-resistant Staphylococcus pseudintermedius, VRE, ESBL- or carbapenemase-producing Enterobacteriaceae and Gram-negative bacteria. In the face of the previously recognized microbiological hazards, a risk assessment tool could be applied in applications for marketing authorization for medicinal products for companion animals. This would allow the approval of new veterinary medicinal antimicrobials for which risk levels are estimated as acceptable for public health.






Changing epidemiology of candidaemia in Australia

2016-11-08

Objectives
Knowledge of contemporary epidemiology of candidaemia is essential. We aimed to identify changes since 2004 in incidence, species epidemiology and antifungal susceptibilities of Candida spp. causing candidaemia in Australia.
Methods
These data were collected from nationwide active laboratory-based surveillance for candidaemia over 1 year (within 2014–2015). Isolate identification was by MALDI-TOF MS supplemented by DNA sequencing. Antifungal susceptibility testing was performed using Sensititre YeastOne™.
Results
A total of 527 candidaemia episodes (yielding 548 isolates) were evaluable. The mean annual incidence was 2.41/105 population. The median patient age was 63 years (56% of cases occurred in males). Of 498 isolates with confirmed species identity, Candida albicans was the most common (44.4%) followed by Candida glabrata complex (26.7%) and Candida parapsilosis complex (16.5%). Uncommon Candida species comprised 25 (5%) isolates. Overall, C. albicans (>99%) and C. parapsilosis (98.8%) were fluconazole susceptible. However, 16.7% (4 of 24) of Candida tropicalis were fluconazole- and voriconazole-resistant and were non-WT to posaconazole. Of C. glabrata isolates, 6.8% were resistant/non-WT to azoles; only one isolate was classed as resistant to caspofungin (MIC of 0.5 mg/L) by CLSI criteria, but was micafungin and anidulafungin susceptible. There was no azole/echinocandin co-resistance.
Conclusions
We report an almost 1.7-fold proportional increase in C. glabrata candidaemia (26.7% versus 16% in 2004) in Australia. Antifungal resistance was generally uncommon, but azole resistance (16.7% of isolates) amongst C. tropicalis may be emerging.