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Preview: Journal of Antimicrobial Chemotherapy - current issue

Journal of Antimicrobial Chemotherapy Current Issue

Published: Wed, 12 Apr 2017 00:00:00 GMT

Last Build Date: Fri, 19 May 2017 06:48:33 GMT


No role for patient body weight on renal function assessment for drug dosing


Objectives: To evaluate the ability of body-weight-driven renal function assessment (RFA) formulae to predict on-target elimination rate ranges for gentamicin in patients with varying degrees of renal function.Methods: A 6 year retrospective pharmacokinetic study was conducted at a university teaching hospital.Results: A total of 85 patients met the inclusion criteria and 127 pharmacokinetic files were analysed from patients on medical-surgical wards (53%) and medical-surgical ICUs (13%) receiving intravenous gentamicin for treatment, as well as those for patients receiving it for surgical prophylaxis (34%). Each RFA formula was examined against standard dosing tables for gentamicin. A table of acceptable elimination rates was generated using a traditional peak of 8 mg/L and trough between 0.5 and 2 mg/L associated with each of the dosing interval extensions. The ability of each RFA formula to select on-target elimination rates was evaluated. The RFA formula assuming a normalized body weight of 72 kg and a modified creatinine reagent adjustment factor of 90% provided the most accurate on-target elimination rate selection. This method was superior to dosing interval selection based on the Modification in Diet Renal Disease (MDRD) formula, Sanford’s guide method, as well as the Cockcroft–Gault formulae using total body weight, ideal body weight or lean body weight (P <0.0001).Conclusions: Based on the use of gentamicin as a surrogate guide for renally adjusted drugs, these results support dosing interval selection based on a normalized body weight method and a formula reagent adjustment factor of 90% within the Cockcroft–Gault formula.

Single-dose pharmacokinetics of tenofovir alafenamide and its active metabolite in the mucosal tissues


Objectives: Tenofovir alafenamide, a prodrug of tenofovir, produces higher PBMC concentrations of tenofovir diphosphate (tenofovir-dp) than tenofovir disoproxil fumarate. To understand tenofovir alafenamide’s mucosal tissue distribution and its implications for pre-exposure prophylaxis, we characterized tenofovir-dp in female genital tract (FGT) and lower gastrointestinal (GI) tissues.Methods: Healthy seronegative women were given 5, 10 or 25 mg of tenofovir alafenamide (n =8/group). Each participant provided plasma, PBMC and cervical, vaginal and rectal tissue samples over 14 days. Plasma, cell lysate and tissue homogenate concentrations were analysed by LC-MS/MS. Dose proportionality was declared in plasma and PBMCs if the natural log AUC versus natural log dose regression line 90% CI was within 0.57–1.43. In vitro tenofovir-dp formation was assessed in PBMCs and ectocervical (Ect1/E6E7) and vaginal (VK2/E6E7) cells incubated in 0.5 and 10 μM tenofovir alafenamide or tenofovir. NCT02357602.Results: Following single doses of 5, 10 and 25 mg, median (IQR) tenofovir plasma AUC0–14 days was 52.8 (49.5–59.6), 78.1 (68.2–86.9) and 169.7 (131.2–211.4) ng·h/mL and tenofovir-dp PBMC AUC0–14 days was 2268 (1519–4090), 4584 (3113–5734) and 9306 (6891–10785) fmol·h/106 cells, respectively. Tenofovir was quantifiable in 52% and 92% of FGT and GI tissues, whereas tenofovir-dp was quantifiable in only 5% and 19% of FGT and GI tissues, respectively. Plasma tenofovir and PBMC tenofovir-dp were dose proportional (90% CI = 0.87–1.15 and 0.62–1.02, respectively). In vitro tenofovir-dp was 1.7–17-fold higher in epithelial cells than PBMCs.Conclusions: After tenofovir alafenamide dosing in vivo, tenofovir-dp was unquantifiable in most tissues (91%) although cervical and vaginal epithelial cells efficiently formed tenofovir-dp from tenofovir alafenamide in vitro. These findings warrant further investigation of tenofovir alafenamide’s pharmacology.

Activity of cefiderocol (S-649266) against carbapenem-resistant Gram-negative bacteria collected from inpatients in Greek hospitals


Background: Cefiderocol (S-649266), a siderophore cephalosporin, utilizes a novel mechanism of entry into the periplasmic space of Gram-negative bacteria and is broadly stable to ESBLs and carbapenemases.Methods: A collection of carbapenem-resistant Gram-negative bacteria isolated from clinical specimens in 18 Greek hospitals was tested for susceptibility to cefiderocol, meropenem, ceftazidime, cefepime, ceftazidime/avibactam, ceftolozane/tazobactam, aztreonam, amikacin, ciprofloxacin, colistin and tigecycline. Broth microdilution plates were used to determine MICs.Results: In total 189 non-fermentative Gram-negative bacteria (107 Acinetobacter baumannii and 82 Pseudomonas aeruginosa) and 282 Enterobacteriaceae (including 244 Klebsiella pneumoniae, 14 Enterobacter cloacae and 11 Providencia stuartii) were studied. For both A. baumannii and P. aeruginosa the MIC90 of cefiderocol was 0.5 mg/L. For K. pneumoniae, E. cloacae and P. stuartii the MIC90 of cefiderocol was 1, 1 and 0.5 mg/L, respectively. Tigecycline was the second most active antibiotic, followed by colistin.Conclusions: Cefiderocol exhibited greater antimicrobial activity in vitro against carbapenem-resistant Gram-negative bacteria than comparator antibiotics.

Resistance gene transfer: induction of transducing phage by sub-inhibitory concentrations of antimicrobials is not correlated to induction of lytic phage


Objectives: Horizontal gene transfer of antimicrobial resistance (AMR) genes between clinical isolates via transduction is poorly understood. MRSA are opportunistic pathogens resistant to all classes of antimicrobial agents but currently no strains are fully drug resistant. AMR gene transfer between Staphylococcus aureus isolates is predominantly due to generalized transduction via endogenous bacteriophage, and recent studies have suggested transfer is elevated during host colonization. The aim was to investigate whether exposure to sub-MIC concentrations of antimicrobials triggers bacteriophage induction and/or increased efficiency of AMR gene transfer.Methods: Isolates from MRSA carriers were exposed to nine antimicrobials and supernatants were compared for lytic phage particles and ability to transfer an AMR gene. A new technology, droplet digital PCR, was used to measure the concentration of genes in phage particles.Results: All antibiotics tested induced lytic phage and AMR gene transduction, although the ratio of transducing particles to lytic particles differed substantially for each antibiotic. Mupirocin induced the highest ratio of transducing versus lytic particles. Gentamicin and novobiocin reduced UV-induced AMR transduction. The genes carried in phage particles correlated with AMR transfer or lytic particle activity, suggesting antimicrobials influence which DNA sequences are packaged into phage particles.Conclusions: Sub-inhibitory antibiotics induce AMR gene transfer between clinical MRSA, while combination therapy with an inhibiting antibiotic could potentially alter AMR gene packaging into phage particles, reducing AMR transfer. In a continually evolving environment, pathogens have an advantage if they can transfer DNA while lowering the risk of lytic death.

Randomized controlled trial of the tolerability and completion of maraviroc compared with Kaletra ® in combination with Truvada ® for HIV post-exposure prophylaxis (MiPEP Trial)


Objectives: Post-exposure prophylaxis (PEP) for HIV is often poorly tolerated and not completed. Alternative PEP regimens may improve adherence and completion, aiding HIV prevention. We conducted a randomized controlled trial of a maraviroc-based PEP regimen compared with a standard-of-care regimen using ritonavir-boosted lopinavir.Methods: Patients meeting criteria for PEP were randomized to tenofovir disoproxil/emtricitabine (200/245 mg) once daily plus ritonavir-boosted lopinavir (Kaletra® 400/100 mg) or maraviroc 300 mg twice daily. The composite primary endpoint was completion of 28 days of the allocated PEP regimen without grade 3 or 4 clinical or laboratory adverse events (AEs) related to the PEP medication.Results: Two hundred and thirteen individuals were randomized (107 to maraviroc; 106 to Kaletra® arm). Follow-up rates were high in both groups. There was no difference in the primary endpoint; 70 (71%) in the maraviroc and 64 (65%) in the Kaletra® arm (P =0.36) completed PEP without grade 3 or 4 AEs. Discontinuation of PEP was the same (18%) in both groups. There were no grade 3 or 4 clinical AEs in either arm, but more grade 1 or 2 clinical AEs in the Kaletra® arm (91% versus 70%; P < 0.001). Antidiarrhoeal medication use was higher in the Kaletra® arm (67% versus 25%; P < 0.001). There were no HIV seroconversions in the study period.Conclusions: The completion rate in the absence of grade 3 or 4 AEs was similar with both regimens. Maraviroc-based PEP was better tolerated, supporting its use as an option for non-occupational PEP.

WCK 5222 (cefepime/zidebactam) antimicrobial activity tested against Gram-negative organisms producing clinically relevant β-lactamases


Background: Zidebactam is a β-lactam enhancer antibiotic with a dual mechanism of action involving binding to Gram-negative PBP2 and β-lactamase inhibition. Cefepime combined with zidebactam (WCK 5222) is under clinical development for treatment of Gram-negative infections.Objectives: To evaluate the in vitro activities of cefepime and zidebactam separately and combined at 1:1 and 2:1 ratios when tested against Gram-negative organisms producing the most clinically relevant β-lactamase types.Methods: β-Lactamase-producing (193) and WT (71) isolates were tested for susceptibility by broth microdilution method against cefepime/zidebactam, cefepime and zidebactam.Results: Cefepime/zidebactam (1:1) was very active against Enterobacteriaceae producing CTX-M-15 (21; MIC50/90 0.25/1 mg/L), SHV (20; MIC50/90 0.12/0.25 mg/L), other ESBLs (20, including GES-18, OXA-1/30 and OXY-, PER-, TEM- and VEB-like; MIC50/90 0.25/1 mg/L), plasmidic AmpC (10; MIC50/90 ≤0.06/≤0.06 mg/L), derepressed AmpC (23; MIC50/90 0.12/0.5 mg/L), KPC (35; MIC50/90 0.25/1 mg/L) and metallo-β-lactamases (MBLs; 20 including VIM, IMP and NDM; MIC50/90 0.5/8 mg/L). Cefepime/zidebactam (1:1) was also active against Pseudomonas aeruginosa with overexpression of AmpC (21; MIC50/90 4/8 mg/L) and MBLs [12 (VIM and IMP); MIC50/90 4/8 mg/L]. Zidebactam alone exhibited potent in vitro activity against some Enterobacteriaceae and P. aeruginosa, including β-lactamase-producing strains. Cefepime/zidebactam MIC values were lower than those of each agent tested alone for many β-lactamase-producing strains, indicating synergy. Cefepime/zidebactam showed moderate activity against OXA-23/24/58-producing Acinetobacter baumannii [MIC50/90 32 mg/L (1:1)].Conclusions: Cefepime/zidebactam showed potent activities against Enterobacteriaceae and P. aeruginosa producing various clinically relevant β-lactamases, including ESBLs, KPCs, AmpC and MBLs for which limited treatment options are currently available.

Drug resistance in antiretroviral-naive children newly diagnosed with HIV-1 in Manaus, Amazonas


Objectives: To determine the prevalence of drug resistance mutations (DRM), the prevalence of drug susceptibility [transmitted drug resistance (TDR)] and the prevalence of HIV-1 variants among treatment-naive HIV-infected children in Manaus, Amazonas state, Brazil.Methods: Children born to HIV-infected mothers and diagnosed with HIV in an HIV reference service centre and with available pol sequence between 2010 and 2015 prior to antiretroviral initiation were included. TDR was identified using the Calibrated Population Resistance Tool. HIV-1 subtypes were defined by Rega and phylogenetic analyses.Results: One hundred and seventeen HIV-infected children with a median age of 3.7 years were included. Among them, 28.2% had been exposed to some form of prevention of mother-to-child transmission (PMTCT). HIV DRM were present in 21.4% of all children. Among PMTCT-exposed children, 3% had NRTI mutations, 15.2% had NNRTI mutations and 3% had PI mutations. Among PMTCT-unexposed children, 1.2% had NRTI mutations, 21.4% had non-NNRTI mutations and 1.2% had PI mutations. The most common DRM was E138A (8.5%). The prevalence of TDR was 16.2%; 21.1% among PMTCT-exposed children and 14.3% among PMTC-unexposed children. The analysis of HIV-1 subtypes revealed that 80.2% were subtype B, 6.0% were subtype C, 3.4% were subtype F1 and 10.3% were possible unique recombinant forms (BF1, 4.3%; DB, 4.3%; BC, 0.9%; KC, 0.9%).Conclusions: We report a high prevalence of DRM in this population, including in almost a quarter of children with no reported PMTCT. The high prevalence of TDR observed might compromise ART effectiveness. Results show extensive HIV-1 diversity and expansion of subtype C, which highlights the need for surveillance of HIV-1 subtypes in Amazonas state.

Antibiotic consumption by New Zealand children: exposure is near universal by the age of 5 years


Background: Increasing concerns about antibiotic resistance and microbiome disruption have stimulated interest in describing antibiotic consumption in young children. Young children are an age group for whom antibiotics are frequently prescribed.Objectives: To describe community antibiotic dispensing during the first 5 years of life in a large, socioeconomically and ethnically diverse cohort of children, and to determine how antibiotic dispensing varied between population subgroups.Methods: This study was performed within the Growing Up in New Zealand longitudinal cohort study ( with linkage to national administrative antibiotic dispensing data. Descriptive statistics and univariate and multivariable associations were determined.Results: The 5581 cohort children received 53 052 antibiotic courses, of which 54% were amoxicillin. By age 5 years, 97% of children had received one or more antibiotic courses, and each child had received a median of eight antibiotic courses (IQR 4–13). The mean incidence of antibiotic dispensing was 1.9 courses/child/year. Multivariable negative binomial regression showed that Māori and Pacific children received more antibiotic courses than European children, as did children in the most-deprived compared with the least-deprived areas. A distinct seasonal pattern was noted.Conclusions: This study provided a detailed description of antibiotic dispensing within a large and diverse child cohort. Antibiotic exposure was near universal by age 5 years. The predominance of amoxicillin use and the seasonal pattern suggest much antibiotic use may have been for self-limiting respiratory infections. There is a need for safe and effective interventions to improve antibiotic prescribing practices for New Zealand children.

Evaluation of the β-CARBA™ test, a colorimetric test for the rapid detection of carbapenemase activity in Gram-negative bacilli


Objectives: There is an urgent need for accurate and fast diagnostic tests to identify carbapenemase-producing bacteria. Here, we have evaluated a novel colorimetric test (the β-CARBA™ test; Bio-Rad) to detect carbapenemase-producing Gram-negative bacilli from cultured colonies.Methods: The performance of the β-CARBA™ test was compared with that of the Carba NP test (or the CarbAcineto NP test) and RAPIDEC® CARBA NP (bioMérieux) using a collection of 290 isolates with characterized β-lactamase content. This collection included 199 carbapenemase producers (121 Enterobacteriaceae, 36 Pseudomonas and 42 Acinetobacter baumannii) and 91 non-carbapenemase producers (55 Enterobacteriaceae, 20 Pseudomonas and 16 A. baumannii).Results: The β-CARBA™ test correctly detected 84.9% of the carbapenemase producers, including all KPC and IMP, 96.4% of VIM, 85.3% of NDM, 80.5% of OXA-48-like and 91.2% of A. baumannii-related OXA carbapenemases (OXA-23, OXA-40, OXA-58, OXA-143 and overexpressed OXA-51). All rare metallo-β-lactamases (SPM, AIM, GIM, DIM and SIM) were detected. Importantly, all non-KPC Ambler class A carbapenemases were not detected, including GES variants with carbapenemase activity (n = 6), IMI (n = 3), NMC-A (n = 1), SME (n = 2), FRI-1 (n = 1) and BIC-1 (n = 1). All non-carbapenemase producers gave a negative result except with OXA-163-, OXA-405- and one TEM-3-producing Citrobacter freundii. The overall sensitivity and specificity of the β-CARBA™ test were 84.9% and 95.6%, respectively. This test is easy to perform and to interpret by non-specialized staff members.Conclusions: Despite lack of specificity towards non-KPC Ambler class A and OXA-48-like carbapenemases, the β-CARBA™ test could complete the existing panel of tests available for the confirmation of carbapenemases in Gram-negatives.

Therapeutic drug monitoring of boosted PIs in HIV-positive patients: undetectable plasma concentrations and risk of virological failure


Background: Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure.Methods: A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards.Results: The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P <0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P =0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL (P <0.001), genotypic susceptibility score ≤2 (P =0.001), lower nadir CD4 cell count (P =0.003) and not being in the adherent group (P =0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks.Conclusions: The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions.

Multiregional dissemination of KPC-producing Klebsiella pneumoniae ST258/ST512 genotypes in Poland, 2010–14


Objectives: In 2008–09, the KPC carbapenemase epidemiology in Poland was dominated by a Klebsiella pneumoniae ST258 KPC-2 outbreak in Warsaw and its administrative region. The aim of this study was to analyse the situation in 2010–14, with a focus on new outbreaks in other parts of the country.Methods: KPCs were detected in all suspected isolates by PCR. The detailed study was performed on 173 isolates from 2010 to 2012, and included PFGE and MLST, PCR identification of K. pneumoniae clonal group CG258 clades and potential specificity markers (pilv-1, IS66 and prp), PCR mapping of Tn4401 transposons, and plasmid analysis by nuclease S1 profiling and PCR-based replicon typing.Results: Six hundred and eight KPC cases were identified in Poland in 2010–14, almost half of which occurred in the Warsaw region, and another half in four other areas. The new outbreaks were caused by four K. pneumoniae CG258 genotypes, different from each other and from the organisms spreading in Warsaw. The new lineages were ST258 or ST512 of clade II, and had specific compositions of potential ST258/ST512 clonal markers. The isolates produced KPC-3 encoded by Tn4401a or Tn4401b elements on plasmids with single or multiple replicons, including I2, FIIK (+/–FIBK), ‘FIIY-like’, X3 and R. Of other species, Citrobacter freundii ST17 and Enterobacter cloacae ST254 with KPC-2 were identified in a Warsaw hospital.Conclusions: The study showed remarkable changes in the KPC epidemiology in Poland in 2010–14, which, following the localized regional spread in the early phase, has converted into multiregional dissemination.

Ecological impact of ciprofloxacin on commensal enterococci in healthy volunteers


Background: The ecological impact of ciprofloxacin on commensal enterococci is unknown.Methods: Forty-eight healthy volunteers received ciprofloxacin from day (D) 0 to D14; stools were collected on D7, D14 and D42. Fluoroquinolone-susceptible and -resistant enterococci (FQ-SE and FQ-RE) were detected and quantified by culture, and identified by MALDI-TOF MS. The relative abundance of FQ-RE over FQ-SE was determined. The genetic basis of fluoroquinolone resistance was deciphered by partial sequencing of gyrA and parC genes. Clonal relatedness was determined by random amplification of polymorphic DNA PCR. Clinical trial no.: NCT00190151.Results: Enterococci were carried by 47/48 (98%) subjects. Total counts were reduced during ciprofloxacin therapy (4.0 and 3.9 log cfu/g on D7 and D14 versus 5.9 log cfu/g before and 6.9 log cfu/g after treatment; P < 0.05). Twenty-one out of 48 (44%) carried FQ-RE; among them, 21/21 carried Enterococcus faecium, 19 carried Enterococcus faecalis and 11 carried other species. Five out of 48 (10%) harboured FQ-RE (ciprofloxacin MIC >4 mg/L) before treatment (all E. faecium), 6 on D7 (3 E. faecium and 3 E. faecalis), 8 on D14 (4 E. faecium and 4 E. faecalis) and 10 (21%) on D42 (9 E. faecium and 1 E. faecalis). The relative abundance of FQ-RE increased from 44% on D0 to 73% and 75% on D7 and D14, respectively. No acquisition of fluoroquinolone resistance among endogenous D0 strains was evidenced. All (14/14) distinct Fluoroquinolone-resistant E. faecalis clones were gyrA/parC double mutants with high-level resistance (ciprofloxacin MIC >64 mg/L). In contrast, 34/35 E. faecium exhibited low-level resistance (ciprofloxacin MIC 4–32 mg/L) with no gyrA/parC mutation, but overexpressed the chromosomal Efmqnr gene. As compared with Fluoroquinolone-susceptible strains, Fluoroquinolone-resistant E. faecium were more frequently ampicillin resistant and Fluoroquinolone-resistant E. faecalis were more highly resistant to gentamicin.Conclusions: Although intrinsically poorly susceptible to fluoroquinolones, gut populations of enterococci are highly impacted both quantitatively and qualitatively by ciprofloxacin.

Promoter characterization and expression of the bla KPC-2 gene in Escherichia coli , Pseudomonas aeruginosa and Acinetobacter baumannii


Objectives: KPC-producing pathogens exhibit variable carbapenem susceptibility levels, which is probably the result of the genetic environment of the blaKPC genes. Here we determined the transcriptional start sites (TSSs) and the expression of the blaKPC-2 gene in various genetic contexts and in different hosts (Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii).Methods: The blaKPC-2 genes along with the upstream sequences derived from Tn4401b (structure A), Tn4401b interrupted by Tn3/IS26 (structure B) and Tn4401b interrupted by Tn5563 (structure C) were cloned in two E. coli shuttle vectors (pBBR1MCS.3 for expression studies in P. aeruginosa and pIM-arr2 for expression studies in A. baumannii). MICs were determined by Etests. 5′ RACE (where RACE stands for rapid amplification of cDNA ends) and quantitative RT–PCR experiments were performed to determine TSSs and transcription levels, respectively.Results: Depending on the bacterial host, different promoters were used for blaKPC-2 gene expression. The highest transcriptional level was obtained in P. aeruginosa with structure C, described only in P. aeruginosa. Tn4401b (structure A), harbouring two promoters (P1 and P2), was the most efficient in E. coli and A. baumannii. This structure was also efficient in P. aeruginosa, although the same deduced promoter was not used (P1, instead of P2 used by E. coli and A. baumannii). Two novel TSSs and putative promoters (P2b and P3b) were identified in structure B. In this structure, P2b and P3b were preferably used in E. coli and in P. aeruginosa, respectively, whereas P1 was used in A. baumannii.Conclusions: We determined the preferred TSSs of the blaKPC gene in each species and described two novel deduced promoters in structure B.

Genomic landscape of extended-spectrum β-lactamase resistance in Escherichia coli from an urban African setting


Objectives: Efforts to treat Escherichia coli infections are increasingly being compromised by the rapid, global spread of antimicrobial resistance (AMR). Whilst AMR in E. coli has been extensively investigated in resource-rich settings, in sub-Saharan Africa molecular patterns of AMR are not well described. In this study, we have begun to explore the population structure and molecular determinants of AMR amongst E. coli isolates from Malawi.Methods: Ninety-four E. coli isolates from patients admitted to Queen’s Hospital, Malawi, were whole-genome sequenced. The isolates were selected on the basis of diversity of phenotypic resistance profiles and clinical source of isolation (blood, CSF and rectal swab). Sequence data were analysed using comparative genomics and phylogenetics.Results: Our results revealed the presence of five clades, which were strongly associated with E. coli phylogroups A, B1, B2, D and F. We identified 43 multilocus STs, of which ST131 (14.9%) and ST12 (9.6%) were the most common. We identified 25 AMR genes. The most common ESBL gene was blaCTX-M-15 and it was present in all five phylogroups and 11 STs, and most commonly detected in ST391 (4/4 isolates), ST648 (3/3 isolates) and ST131 [3/14 (21.4%) isolates].Conclusions: This study has revealed a high diversity of lineages associated with AMR, including ESBL and fluoroquinolone resistance, in Malawi. The data highlight the value of longitudinal bacteraemia surveillance coupled with detailed molecular epidemiology in all settings, including low-income settings, in describing the global epidemiology of ESBL resistance.

Predisposing factors and outcome of uncommon yeast species-related fungaemia based on an exhaustive surveillance programme (2002–14)


Objectives: Using registry data to compare fungaemia caused by uncommon yeast species (UYS; i.e. other than Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Candida krusei) and C. albicans-related fungaemia can reveal specific predisposing factors of UYS with potential impact on treatment strategies.Methods: We analysed 338 episodes of UYS fungaemia prospectively collected from 27 hospitals (Paris, France; 1 October 2002–31 December 2014) and compared these with 1998 single episodes of C. albicans fungaemia using univariate and multivariate analyses.Results: The proportion of UYS fungaemia was stable over time. Thirty-five different species were identified (27 ascomycetes, 8 basidiomycetes), 11 had caspofungin MIC50  >0.25 mg/L and 15 fluconazole MIC50  >4 mg/L. Haematological malignancies [OR=2.39 (95% CI 1.79–3.18)] and prior exposure to antifungal drugs [OR=1.87 (1.30–2.69)] were independent predisposing factors for UYS infections upon multivariate analysis. However, when considering the genus/species complex level, only infections due to Candida kefyr-related species [OR=4.01 (2.42–6.64)] and to Trichosporon spp. [OR=5.38 (1.72–16.81)] remained associated with haematological malignancies, those due to the GEOTRICHUM group with acute leukaemia [OR=61.29 (19.23–195.36)], and infections with Trichosporon spp. or the GEOTRICHUM group with prior exposure to caspofungin [OR=15.67 (3.62–67.80) and OR=13.17 (3.33–52.03), respectively] but not to fluconazole. The global mortality at day 30 for UYS was similar to that for C. albicans (35.4%, and 39.9%, respectively), but very divergent results were observed according to the specific UYS.Conclusions: UYS encompass a high diversity of species, each with its own behaviour and predisposing factors for human infections. This variety makes it important to rapidly identify an isolate to the species level in order to optimize antifungal treatment.

Comparative effectiveness of linezolid versus vancomycin as definitive antibiotic therapy for heterogeneously resistant vancomycin-intermediate coagulase-negative staphylococcal central-line-associated bloodstream infections in a neonatal intensive care unit


Objectives: Heterogeneously resistant vancomycin-intermediate coagulase-negative staphylococci (hVICoNS) are emerging pathogens causing central-line-associated bloodstream infections (CLABSIs) in neonatal intensive care unit (NICU) patients. Given the burden of disease associated with CLABSI and the current lack of therapeutic guidelines, we aimed to compare the effectiveness of linezolid versus vancomycin used as the definitive antibiotic therapy for hVICoNS CLABSI.Methods: We performed a retrospective cohort study of infants with hVICoNS CLABSI from a single NICU between 2009 and 2014, treated with either linezolid or vancomycin as definitive antibiotic therapy. CLABSI duration, early and late recurrence and in-hospital mortality were compared using propensity score-adjusted proportional hazards and logistic regression models.Results: Of 89 infants with hVICoNS CLABSI, 33 (37.1%) treated with linezolid were compared with 56 (62.9%) treated with vancomycin. The median duration of CLABSI was 5 (range 1–12) versus 4 days (range 0–14) (P =0.11), early recurrences were 3.0% versus 7.1% (P =0.42), late recurrences 0% versus 14.3% (P =0.02) and mortality 27.3% versus 28.6% (P =0.90), when treated with linezolid versus vancomycin, respectively. When adjusting using a continuous propensity score, linezolid had an HR of 0.78 (95% CI 0.48–1.27) for CLABSI duration, an OR of 0.23 (95% CI 0.02–2.56) for early recurrence and an OR of 0.9 (95% CI 0.3–2.67) for mortality, relative to vancomycin.Conclusions: There was no statistically significant difference between linezolid and vancomycin when used as definitive treatment for hVICoNS CLABSI in NICU patients, in terms of CLABSI duration, recurrence or all-cause mortality.

Evaluation of the new GenoType NTM-DR kit for the molecular detection of antimicrobial resistance in non-tuberculous mycobacteria


Objectives: Non-tuberculous mycobacteria (NTM) are emerging pathogens causing difficult-to-treat infections. We tested a new assay (GenoType NTM-DR) that detects natural and acquired resistance mechanisms to macrolides and aminoglycosides in frequently isolated NTM species.Methods: Performance was assessed on 102 isolates including reference strains [16 Mycobacterium avium, 10 Mycobacterium intracellulare, 8 Mycobacterium chimaera, 15 Mycobacterium chelonae and 53 Mycobacterium abscessus (including subsp. abscessus isolates, 18 with a t28 in erm(41) and 10 with a c28, 13 subsp. bolletii isolates and 12 subsp. massiliense isolates)]. Genotypes were determined by PCR sequencing of erm(41) and rrl for clarithromycin resistance and of the 1400–1480 rrs region for aminoglycoside resistance. Phenotypes were determined by MIC microdilution.Results: GenoType NTM-DR yielded results concordant with Sanger sequencing for 100/102 (98%) isolates. The erm(41) genotypic pattern was accurately identified for M. abscessus isolates. Mutations in rrl were detected in 15 isolates (7 M. avium complex, 5 M. abscessus and 3 M. chelonae) with acquired clarithromycin resistance harbouring rrl mutations (a2057c, a2058g, a2058t or a2059c). Mutations in rrs were detected in five isolates with amikacin resistance harbouring the rrs mutation a1408g. In two isolates, the NTM-DR test revealed an rrl mutation (initial sequencing being WT), which was confirmed by re-sequencing. The test results were concordant with phenotypic susceptibility testing in 96/102 (94.1%) isolates, with four clarithromycin-resistant and two amikacin-resistant isolates not harbouring mutations.Conclusions: The GenoType NTM-DR test is efficient in detecting mutations predictive of antimicrobial resistance in M. avium complex, M. abscessus and M. chelonae.

Tolerability of integrase inhibitors in a real-life setting


Background: Integrase inhibitors have shown better tolerability than other drugs in clinical trials, but some post-marketing data have suggested potential differences among them.Aims: We compared rates and reasons for discontinuation of raltegravir-, elvitegravir- and dolutegravir-based regimens in a large cohort of HIV-infected patients.Methods: Retrospective analysis of a prospectively followed cohort including all antiretroviral-naive and all virologically suppressed antiretroviral-experienced patients prescribed a first regimen containing raltegravir, elvitegravir or dolutegravir with at least one follow-up visit. Major outcomes were early discontinuation (≤1 year) due to any reason and more specifically due to toxicity. Incidence was calculated as number of episodes per 1000 person-years. Risk factors for discontinuation were assessed by multivariate Cox models.Results: Early discontinuations due to any reason were 271 (raltegravir), 168 (elvitegravir) and 264 (dolutegravir) per 1000 patient-years (P =0.0821). Early discontinuations due to toxicity were 76 (raltegravir), 103 (elvitegravir) and 81 (dolutegravir) per 1000 patient-years (P =0.6792). Overall, the most common toxicities leading to discontinuation were neuropsychiatric, osteomuscular or digestive. Most frequent neuropsychiatric manifestations reported at discontinuation were insomnia, dizziness, headache and anxiety irrespective of the integrase inhibitor. Among discontinuations due to toxicity, neuropsychiatric effects were more common with dolutegravir than with raltegravir or elvitegravir (P =0.0046). Age (HR 1.04, 95% CI 1.02–1.07, P =0.0007) was the only independent risk factor for early discontinuation due to toxicity.Conclusions: Discontinuations due to any reason tended to be less common with elvitegravir, but discontinuations due to toxicity did not differ among integrase inhibitors. Neuropsychiatric toxicity leading to drug discontinuation was more frequent with dolutegravir.

Effect of adding a mobile health intervention to a multimodal antimicrobial stewardship programme across three teaching hospitals: an interrupted time series study


Objectives: To evaluate the impact of adding a mobile health (mHealth) decision support system for antibiotic prescribing to an established antimicrobial stewardship programme (ASP).Methods: In August 2011, the antimicrobial prescribing policy was converted into a mobile application (app). A segmented regression analysis of interrupted time series was used to assess the impact of the app on prescribing indicators, using data (2008–14) from a biannual point prevalence survey of medical and surgical wards. There were six data points pre-implementation and six data points post-implementation.Results: There was an increase in compliance with policy (e.g. compliance with empirical therapy or expert advice) in the two specialties of medicine (6.48%, 95% CI = −1.25 to 14.20) and surgery (6.63%, 95% CI = 0.15–13.10) in the implementation period, with a significant sudden change in level in surgery (P <0.05). There was an increase, though not significant, in medicine (15.20%, 95% CI = −17.81 to 48.22) and surgery (35.97%, 95% CI = −3.72 to 75.66) in the percentage of prescriptions that had a stop/review date documented. The documentation of indication decreased in both medicine (−16.25%, 95% CI = −42.52 to 10.01) and surgery (−14.62%, 95% CI = −42.88 to 13.63).Conclusions: Introducing the app into an existing ASP had a significant impact on the compliance with policy in surgery, and a positive, but not significant, effect on documentation of stop/review date in both specialties. The negative effect on the third indicator may reflect a high level of compliance pre-intervention, due to existing ASP efforts. The broader value of providing an antimicrobial policy on a digital platform, e.g. the reach and access to the policy, should be measured using indicators more sensitive to mHealth interventions.

The complexity of minocycline serum protein binding


Objectives: Serum protein binding is critical for understanding the pharmacology of antimicrobial agents. Tigecycline and eravacycline were previously reported to have atypical non-linear protein binding; the percentage of free fraction decreased with increasing total concentration. In this study, we extended the investigation to other tetracyclines and examined the factors that might impact protein binding.Methods: Different minocycline concentrations (0.5–50 mg/L) and perfusion media (saline, 0.1 M HEPES buffer and 0.1 and 1 M PBS) were examined by in vitro microdialysis. After equilibration, two dialysate samples were taken from each experiment and the respective antimicrobial agent concentrations were analysed by validated LC-MS/MS methods. For comparison, the serum protein bindings of doxycycline and levofloxacin were also determined.Results: The free fraction of minocycline decreased with increasing total concentration, and the results depended on the perfusion media used. The trends of minocycline protein binding in mouse and human sera were similar. In addition, serum protein binding of doxycycline showed the same concentration-dependent trend as minocycline, while the results of levofloxacin were concentration independent.Conclusions: The serum protein bindings of minocycline and doxycycline are negatively correlated with their total concentrations. It is possible that all tetracyclines share the same pharmacological property. Moreover, the specific perfusion media used could also impact the results of microdialysis. Additional studies are warranted to understand the mechanism(s) and clinical implications of serum protein binding of tetracyclines.

Prevalence of HIV-1 drug resistance in treated patients with viral load >50 copies/mL: a 2014 French nationwide study


Background: Surveillance of HIV-1 resistance in treated patients with a detectable viral load (VL) is important to monitor, in order to assess the risk of spread of resistant viruses and to determine the proportion of patients who need new antiretroviral drugs with minimal cross-resistance.Methods: The HIV-1 protease and reverse transcriptase (RT) and integrase genes were sequenced in plasma samples from 782 consecutive patients on failing antiretroviral regimens, seen in 37 specialized centres in 2014. The genotyping results were interpreted using the ANRS v24 algorithm. Prevalence rates were compared with those obtained during a similar survey conducted in 2009.Results: The protease and RT sequences were obtained in 566 patients, and the integrase sequence in 382 patients. Sequencing was successful in 60%, 78%, 78% and 87% of patients with VLs of 51–200, 201–500, 501–1000 and >1000 copies/mL, respectively. Resistance to at least one antiretroviral drug was detected in 56.3% of samples. Respectively, 3.9%, 8.7%, 1.5% and 3.4% of patients harboured viruses that were resistant to any NRTI, NNRTI, PI and integrase inhibitor (INI). Resistance rates were lower in 2014 than in 2009. Resistance was detected in 48.5% of samples from patients with a VL between 51 and 200 copies/mL.Conclusion: In France in 2014, 90.0% of patients in AIDS care centres were receiving antiretroviral drugs and 12.0% of them had VLs >50 copies/mL. Therefore, this study suggests that 6.7% of treated patients in France might transmit resistant strains. Resistance testing may be warranted in all treated patients with VL > 50 copies/mL.

Antibiotic prescribing frequency amongst patients in primary care: a cohort study using electronic health records


Background: Reducing inappropriate antibiotic prescribing in primary care is a public health priority.Objectives: We hypothesized that a subset of patients account for the majority of antibiotic prescriptions in primary care. We investigated the relationship between the total amount of antibiotics prescribed, individual-level antibiotic use and comorbidity.Methods: This was a cohort study using electronic health records from 1 948 390 adults registered with 385 primary care practices in the UK in 2011–13. We estimated the average number of antibiotic prescriptions per patient and the association between prescribing and comorbidity. We modelled the impact on total prescribing of reducing antibiotic use in those prescribed antibiotics most frequently.Results: On average 30.1% (586 194/1 948 390) of patients were prescribed at least one antibiotic per year. Nine percent (174 602/1 948 390) of patients were prescribed 53% (2 091 496/3 922 732) of the total amount of antibiotics, each of whom received at least five antibiotic prescriptions over 3 years. The presence of any comorbidity increased the prescribing rate by 44% [adjusted incidence rate ratio (IRR) 1.44, 95% CI 1.43–1.45]; rates of prescribing to women exceeded those in men by 62% (adjusted IRR 1.62, 95% CI 1.62–1.63).Conclusions: Half of antibiotics prescribed to adults in primary care were for <10% of patients. Efforts to tackle antimicrobial resistance should consider the impact of this on total prescribing.

Susceptibilities of MDR Mycobacterium tuberculosis isolates to unconventional drugs compared with their reported pharmacokinetic/pharmacodynamic parameters


Background: The second-line drugs recommended to treat drug-resistant TB are toxic, expensive and difficult to procure. Given increasing resistance, the need for additional anti-TB drugs has become more urgent. But new drugs take time to develop and are expensive. Some commercially available drugs have reported anti-mycobacterial activity but are not routinely used because supporting laboratory and clinical evidence is sparse.Methods: We analysed 217 MDR M. tuberculosis isolates including 153 initial isolates from unique patients and 64 isolates from follow-up specimens during the course of treatment. The resazurin microdilution assay was performed to determine MICs of trimethoprim/sulfamethoxazole, mefloquine, thioridazine, clofazimine, amoxicillin/clavulanate, meropenem/clavulanate, nitazoxanide, linezolid and oxyphenbutazone. Isoniazid was used for validation. We calculated the MIC50 and MIC90 as the MICs at which growth of 50% and 90% of isolates was inhibited, respectively.Results: The MIC50s, in mg/L, for initial isolates were as follows: trimethoprim/sulfamethoxazole, 0.2/4; mefloquine, 8; thioridazine, 4; clofazimine, 0.25; amoxicillin/clavulanate, 16/8; meropenem/clavulanate, 1/2.5; nitazoxanide, 16; linezolid, 0.25; and oxyphenbutazone, 40. The MIC90s, in mg/L, for initial isolates were as follows: trimethoprim/sulfamethoxazole, 0.4/8; mefloquine, 8; thioridazine, 8; clofazimine, 0.5; amoxicillin/clavulanate, 32/16; meropenem/clavulanate, 8/2.5; nitazoxanide, 16; linezolid, 0.25; and oxyphenbutazone, 60. By comparison, the MIC90 of isoniazid was >4 mg/L, as expected. There was no evidence that previous treatment affected susceptibility to any drug.Conclusions: Most drugs demonstrated efficacy against M. tuberculosis. When these MICs are compared with the published pharmacokinetic/pharmacodynamic profiles of the respective drugs in humans, trimethoprim/sulfamethoxazole, meropenem/clavulanate, linezolid, clofazimine and nitazoxanide appear promising and warrant further clinical investigation.

Increased activity of colistin in combination with amikacin against Escherichia coli co-producing NDM-5 and MCR-1


Objectives: Colistin and carbapenem are two lines of last-resort antibiotics against lethal infections caused by MDR Gram-negative pathogens. The emergence of carbapenemase-positive Escherichia coli with colistin resistance poses a serious threat to public health worldwide. Here we report, for the first time (to the best of our knowledge), a novel combination therapy used for the treatment of E. coli co-producing MCR-1 and NDM-5.Methods: The MICs of colistin were determined alone and with 1–4 mg/L amikacin. A 7-by-4 time–kill array of colistin (0, 0.5, 1, 2, 4, 8 and 16 mg/L) and amikacin (0, 1, 2 and 4 mg/L) over 48 h was designed to characterize the in vitro activity of these agents alone and in combination against each E. coli isolate at an inoculum of 106 and 108 cfu/mL. The sigmoid Emax model was utilized for better delineation of the concentration–effect relationship of each combination. In vivo effectiveness was investigated using a mouse model (combination therapy with intraperitoneal colistin plus amikacin compared with monotherapy).Results: For colistin-resistant isolates, the addition of amikacin demonstrated augmented susceptibility, reducing colistin MICs below the current susceptibility breakpoint. A concentration-dependent decrease in the EC50 values of colistin was observed for all study isolates in the presence of increasing amikacin concentrations. Further in vivo treatment experiments demonstrated that this combination could achieve 1.5–2.8 log10 killing after 24 h of therapy, while monotherapy was unable to achieve such a killing effect.Conclusions: The combination of colistin and amikacin may be a promising therapeutic option for the treatment of lethal infections caused by NDM-5-bearing MCR-1-positive superbugs.

Candida auris candidaemia in Indian ICUs: analysis of risk factors


Objectives: To identify the risk factors associated with Candida auris candidaemia, as this fungus now poses a global threat.Methods: We performed a subgroup analysis of a previously reported study of 27 Indian ICUs. The clinical data of candidaemia cases due to C. auris and other Candida species were compared to determine significant risk factors associated with C. auris infection.Results: Of the 1400 candidaemia cases reported earlier, 74 (5.3%) from 19 of 27 ICUs were due to C. auris. The duration of ICU stay prior to candidaemia diagnosis was significantly longer in patients with C. auris candidaemia (median 25, IQR 12–45 days) compared with the non-auris group (median 15, IQR 9–28, P <0.001). Based on logistic regression modelling, admission to north Indian ICUs [OR 2.1 (1.2–3.8); P =0.012], public-sector hospital [OR 2.2 (1.2–3.9); P =0.006], underlying respiratory illness [OR 2.1 (1.3–3.6); P =0.002], vascular surgery [OR 2.3 (1.00–5.36); P =0.048], prior antifungal exposure [OR 2.8 (1.6–4.8); P <0.001] and low APACHE II score [OR 0.8 (0.8–0.9); P =0.007] were significantly associated with C. auris candidaemia. The majority (45/51, 88.2%) of the isolates were clonal. A considerable number of isolates were resistant to fluconazole (n =43, 58.1%), amphotericin B (n =10, 13.5%) and caspofungin (n =7, 9.5%).Conclusions: Although C. auris infection has been observed across India, the number of cases is higher in public-sector hospitals in the north of the country. Longer stay in ICU, underlying respiratory illness, vascular surgery, medical intervention and antifungal exposure are the major risk factors for acquiring C. auris infection even among patients showing lower levels of morbidity.

Analysis of bla SHV-12 -carrying Escherichia coli clones and plasmids from human, animal and food sources


Objectives: This study aimed at characterizing 23 Escherichia coli isolates from various sources and their respective blaSHV-12-carrying plasmids and sequencing one of these plasmids completely.Methods: Isolates were typed by XbaI-PFGE, MLST and PCR-based phylotyping. Transformed blaSHV-12-carrying plasmids were examined by replicon typing, S1-nuclease, conjugation, EcoRI-HindIII-BamHI digests and plasmid MLST. Co-located resistance genes and integrons as well as the blaSHV-12 genetic environment were analysed by PCR and sequencing. One IncI1 plasmid was sequenced completely using HiSeq 2500 and gap closure by PCRs and Sanger sequencing.Results: Among the 23 SHV-12-positive E. coli, some isolates from different sources showed the same characteristics: ST23/phylogroup A (human, dog, livestock), ST57/D (wild bird, chicken meat) and ST117/D (chicken meat, chicken). All blaSHV-12 genes were horizontally transferable via 30–120 kb plasmids of incompatibility groups IncI1 (n = 17), IncK (n = 3), IncF (n = 1), IncX3 (n = 1) and a non-typeable plasmid. IncK plasmids, indistinguishable in size and restriction patterns, were found in isolates from different sources (ST57/D, meat; ST131/B2, meat; ST57/B1, dog). The IncI1-blaSHV-12-carrying plasmids were mostly assigned to plasmid ST (pST) 26 and pST3. Three plasmids showed novel pSTs (pST214, pST215). The majority of the IncI1 transformants exhibited resistance to β-lactams, chloramphenicol and streptomycin (in relation with a class 1 integron containing an estX-psp-aadA2-cmlA1-aadA1-qacI gene cassette array), and to tetracycline. A novel blaSHV-12 environment was detected and whole plasmid sequencing revealed a Tn21-derived-blaSHV12-ΔTn1721 resistance complex.Conclusions: Results from this study suggest that the dissemination of blaSHV-12 genes occurs by vertical (clonal) and horizontal transfer, the latter mainly mediated through IncI1 multidrug-resistance plasmids.

Fully automated disc diffusion for rapid antibiotic susceptibility test results: a proof-of-principle study


Background: Antibiotic resistance poses a significant threat to patients suffering from infectious diseases. Early readings of antibiotic susceptibility test (AST) results could be of critical importance to ensure adequate treatment. Disc diffusion is a well-standardized, established and cost-efficient AST procedure; however, its use in the clinical laboratory is hampered by the many manual steps involved, and an incubation time of 16–18 h, which is required to achieve reliable test results.Methods: We have evaluated a fully automated system for its potential for early reading of disc diffusion diameters after 6–12 h of incubation. We assessed availability of results, methodological precision, categorical agreement and interpretation errors as compared with an 18 h standard. In total, 1028 clinical strains (291 Escherichia coli, 272 Klebsiella pneumoniae, 176 Staphylococcus aureus and 289 Staphylococcus epidermidis) were included in this study. Disc diffusion plates were streaked, incubated and imaged using the WASPLabTM automation system.Results and conclusions: Our results demonstrate that: (i) early AST reading is possible for important pathogens; (ii) methodological precision is not hampered at early timepoints; and (iii) species-specific reading times must be selected. As inhibition zone diameters change over time and are phenotype/drug combination dependent, specific cut-offs and expert rules will be essential to ensure reliable interpretation and reporting of early susceptibility testing results.

WCK 4234, a novel diazabicyclooctane potentiating carbapenems against Enterobacteriaceae, Pseudomonas and Acinetobacter with class A, C and D β-lactamases


Background: Several diazabicyclooctanes (DBOs) are under development as inhibitors of class A and C β-lactamases. Inhibition of OXA (class D) carbapenemases is variable, with those of Acinetobacter spp. remaining notably resistant. We describe a novel DBO, WCK 4234 (Wockhardt), with distinctive activity against OXA carbapenemases.Methods: MICs of imipenem and meropenem were determined by CLSI agar dilution with WCK 4234 added at 4 or 8 mg/L. Test organisms were clinical Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa with carbapenemases or carbapenem resistance via porin loss plus AmpC or ESBL activity. AmpC mutants were also tested.Results: WCK 4234, which lacked direct antibacterial activity, strongly potentiated imipenem and meropenem against Enterobacteriaceae with OXA-48/OXA-181 or KPC enzymes, or with combinations of impermeability and AmpC or ESBL activity, with MICs reduced to ≤2 mg/L in almost all cases. Carbapenems likewise were potentiated against P. aeruginosa (n =2) with OXA-181 enzyme, with MICs reduced from 64–128 to 2–8 mg/L and against A. baumannii with OXA carbapenemases, particularly OXA-23 or hyperproduced OXA-51, with MICs reduced to ≤2 mg/L for 9/10 acinetobacters with OXA-23 enzyme. Carbapenems were not potentiated against Enterobacteriaceae or non-fermenters with metallo-β-lactamases.Conclusions: WCK 4234 distinctively overcame resistance mediated by OXA-type carbapenemases, including those of A. baumannii. It behaved similarly to other DBOs against strains with KPC carbapenemases or combinations of impermeability and ESBL or AmpC activity.

Oxidative stress and TB outcomes in patients with diabetes mellitus?


In patients with diabetes mellitus, TB treatment outcomes are poorer. Most parameters, when measured, reflect the slower bacteriological conversion from positivity to negativity and higher risks of disease relapse and mortality, as well as a greater propensity to develop drug-resistant TB. Aside from the well-known immunological dysfunction inherent to patients with diabetes mellitus, oxidative stress is likely a major underlying mechanism adversely impacting their TB treatment outcomes. Mycobacterium tuberculosis persisters, formed as a result of the core dormancy response to stress, possibly play a central role in this hypothesis. This hypothetical model also underscores the paramount importance of programmatic management of TB and diabetes mellitus, in collaboration, to improve the outcomes of patients with both diseases. The validity of these ideas could be further ascertained by laboratory and clinical research.

Minocycline attenuates colistin-induced neurotoxicity via suppression of apoptosis, mitochondrial dysfunction and oxidative stress


Background: Neurotoxicity is an adverse effect patients experience during colistin therapy. The development of effective neuroprotective agents that can be co-administered during polymyxin therapy remains a priority area in antimicrobial chemotherapy. The present study investigates the neuroprotective effect of the synergistic tetracycline antibiotic minocycline against colistin-induced neurotoxicity.Methods: The impact of minocycline pretreatment on colistin-induced apoptosis, caspase activation, oxidative stress and mitochondrial dysfunction were investigated using cultured mouse neuroblastoma-2a (N2a) and primary cortical neuronal cells.Results: Colistin-induced neurotoxicity in mouse N2a and primary cortical cells gives rise to the generation of reactive oxygen species (ROS) and subsequent cell death via apoptosis. Pretreatment of the neuronal cells with minocycline at 5, 10 and 20 μM for 2 h prior to colistin (200 μM) exposure (24 h), had an neuroprotective effect by significantly decreasing intracellular ROS production and by upregulating the activities of the anti-ROS enzymes superoxide dismutase and catalase. Minocycline pretreatment also protected the cells from colistin-induced mitochondrial dysfunction, caspase activation and subsequent apoptosis. Immunohistochemical imaging studies revealed colistin accumulates within the dendrite projections and cell body of primary cortical neuronal cells.Conclusions: To our knowledge, this is first study demonstrating the protective effect of minocycline on colistin-induced neurotoxicity by scavenging of ROS and suppression of apoptosis. Our study highlights that co-administration of minocycline kills two birds with one stone: in addition to its synergistic antimicrobial activity, minocycline could potentially ameliorate unwanted neurotoxicity in patients undergoing polymyxin therapy.

Early in vitro development of daptomycin non-susceptibility in high-level aminoglycoside-resistant Enterococcus faecalis predicts the efficacy of the combination of high-dose daptomycin plus ampicillin in an in vivo model of experimental endocarditis


Background: Previous studies showed development of daptomycin non-susceptibility (DNS: MIC >4 mg/L) in Enterococcus faecalis infections. However, no studies have assessed the efficacy of the combination of daptomycin/ampicillin against E. faecalis strains developing DNS in the experimental endocarditis (EE) model.Objectives: To assess the in vitro and in vivo efficacy of daptomycin at 10 mg/kg/day, daptomycin/ampicillin and ampicillin/ceftriaxone against two high-level aminoglycoside-resistant E. faecalis strains, one developing DNS after in vitro exposure to daptomycin and another that did not (DS).Methods: Subculture of 82 E. faecalis strains from patients with endocarditis with daptomycin MICs, time–kill and in vivo experiments using the EE model.Results: 33% of the strains (27 of 82) displayed DNS after subculture with daptomycin. Daptomycin MIC rose from 0.5–2 to 8–16 mg/L. In time–kill experiments, when using a high inoculum (108 cfu/mL), daptomycin/ampicillin was synergistic for one-third of DS strains and none of DNS strains, while ampicillin/ceftriaxone retained synergy in all cases. In the EE model, daptomycin did not significantly reduce cfu/g from vegetations compared with control against either strain, while daptomycin/ampicillin reduced significantly more cfu/g than daptomycin against the DS strain, but not against the DNS strain [2.9 (2.0–4.1) versus 6.1 (4.5–8.0); P =0.002]. Ampicillin/ceftriaxone was synergistic and bactericidal against both strains, displaying the same activity as daptomycin/ampicillin against the DS strain.Conclusions: Performance of an Etest for daptomycin MIC after subculture with daptomycin inhibitory doses on strains of high-level aminoglycoside-resistant E. faecalis endocarditis may be an easy test to predict the in vivo efficacy of daptomycin/ampicillin.

Safety and effectiveness of neuraminidase inhibitors in situations of pandemic and/or novel/variant influenza: a systematic review of the literature, 2009–15


Objectives: To review systematically the published literature evaluating neuraminidase inhibitor (NI) safety and effectiveness in situations of pandemic and novel/variant influenza.Methods: We searched six online databases using comprehensive search criteria for observational studies and randomized controlled trials investigating the effects of NI treatment, prophylaxis or outbreak control in patients of all ages.Results: Overall, 165 studies were included (95% observational), which were generally of low methodological quality due to lack of adjustment for confounding variables. In studies reporting adjusted estimates in general populations, NI treatment appeared likely to be effective against mortality (primarily if administered within 48 h of symptom onset) and potentially effective in reducing pneumonia. NIs appeared effective in reducing secondary transmission when indicated for prophylaxis. Limited, low-quality data suggest NIs are likely safe in general populations and may be safe in pregnant women and children. Data are scarce regarding safety of NIs in adults and high-risk individuals.Conclusions: Most included studies were observational, statistically underpowered and at high risk of reporting biased and/or confounded effect estimates. NI treatment appeared likely effective in reducing mortality (cause unspecified) and pneumonia in general populations, with increasing benefit when administered with 48 h of symptom onset. NI pre- or post-exposure prophylaxis is likely effective in reducing secondary transmission of influenza in a general population. Our evidence suggests NIs are likely safe to use in the general population; however, data for children and pregnant women are limited. Knowledge gaps persist in specific populations such as Aboriginals, high-risk individuals and the elderly.

In vitro and in vivo antifungal activities of T-2307, a novel arylamidine, against Cryptococcus gattii : an emerging fungal pathogen


Objectives: T-2307, a novel arylamidine, exhibits potent broad-spectrum activities against the majority of fungal pathogens. In this study, the antifungal activity of T-2307 against Cryptococcus gattii was evaluated in comparison with those of amphotericin B, fluconazole and voriconazole in vitro and in vivo.Methods: The MICs for 15 clinical isolates were determined according to CLSI guidelines and time–kill studies were performed using C. gattii YF2784. In a murine model for intranasal pulmonary infection caused by C. gattii YF2784, the test compounds were administered once daily for 7 days from 2 h or 14 days post-infection. The viable counts in the lungs and brain were determined at 21 days post-infection.Results: The MIC range, MIC50, MIC90 and geometric mean MIC of T-2307 were 0.0078–0.0625, 0.0313, 0.0625 and 0.0394 mg/L, respectively. The MIC of T-2307 was significantly lower than those of fluconazole, voriconazole and amphotericin B. T-2307 showed concentration-dependent fungicidal activity at 4 times the MIC or higher. Administration of T-2307 at 2 mg/kg/day, amphotericin B at 1 mg/kg/day and fluconazole at 160 mg/kg/day from 2 h post-infection significantly reduced viable counts in the lungs and brain. However, when the administration was started 14 days post-infection, only T-2307 significantly reduced the viable counts in both the lungs and the brain at 1 mg/kg/day.Conclusions: T-2307 shows excellent in vitro and in vivo antifungal activities against C. gattii and would be a promising new candidate for the treatment of cryptococcosis.

Emergence of a plasmid-borne multidrug resistance gene cfr (C) in foodborne pathogen Campylobacter


Objectives: To identify and characterize a novel cfr variant that recently emerged and confers multidrug resistance in Campylobacter, a major foodborne pathogen.Methods: WGS was initially used to identify the cfr(C) gene in Campylobacter isolates and its function was further verified by cloning into an antibiotic-susceptible Campylobacter jejuni strain. Distribution of cfr(C) in various Campylobacter isolates was determined by PCR analysis. Genotyping of cfr(C)-positive strains was done by PFGE and MLST.Results: The cfr(C) gene is predicted to encode a protein that shares 55.1% and 54.9% identity with Cfr and Cfr(B), respectively. cfr(C) was located on a conjugative plasmid of ∼48 kb. Cloning of cfr(C) into C. jejuni NCTC 11168 and conjugative transfer of the cfr(C)-containing plasmid confirmed its role in conferring resistance to phenicols, lincosamides, pleuromutilins and oxazolidinones, and resulted in an 8–256-fold increase in their MICs in both C. jejuni and Campylobacter coli. The cfr(C) gene was detected in multiple C. coli (34 of 344; 10%) isolates derived from different cattle farms in different states, and molecular typing of the cfr(C)-positive C. coli isolates revealed its spread mainly via clonal expansion.Conclusions: These results identify cfr(C) as a new multidrug resistance mechanism in Campylobacter and suggest the potential transmission of this mechanism via the foodborne route, warranting enhanced efforts to monitor its spread in Campylobacter and other foodborne pathogens.

Switch as maintenance to elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate: week 48 results in a clinical cohort


Objectives: To assess, in a clinical cohort, the efficacy of switching current ART in virologically suppressed patients to elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate as a single-tablet regimen (STR) using the PCR signal of the plasma viral load (pVL) assay and determination of plasma drug concentration (C24).Patients and methods: This was an observational single-centre study enrolling antiretroviral-treated patients with pVL <50 copies/mL initiating elvitegravir-based STR. PCRneg was defined as an undetected PCR signal.Results: One hundred and fifty-one patients were enrolled. At STR baseline, the median time since first ART and time of virological suppression were 5 years (IQR 3–9) and 24 months (IQR 9–44), respectively. By week (W) 48, 26 (17%) of the patients had discontinued STR due to adverse events. The proportion of patients maintaining pVL <50 copies/mL on treatment was 98%, 96%, 93% and 97% at W12, W24, W36 and W48, respectively. Five patients (3.3%) experienced a virological failure and emergence of resistance was observed in two of them with the selection of M184V and N155H mutations. At baseline, W12, W24, W36 and W48, 70%, 57%, 72%, 61% and 74% of the patients with pVL <20 copies/mL had a PCRneg, respectively. The median elvitegravir plasma C24 value was 648 ng/mL (IQR 348–989; n =237), with 84% of elvitegravir C24 values >45 ng/mL, the protein-adjusted IC95.Conclusions: In this clinical cohort of virologically suppressed patients switching to STR, most subjects had adequate elvitegravir C24 values with a high proportion maintaining virological suppression with no residual viraemia until W48.

Overexpression of antibiotic resistance genes in hospital effluents over time


Objectives: Effluents contain a diverse abundance of antibiotic resistance genes that augment the resistome of receiving aquatic environments. However, uncertainty remains regarding their temporal persistence, transcription and response to anthropogenic factors, such as antibiotic usage. We present a spatiotemporal study within a river catchment (River Cam, UK) that aims to determine the contribution of antibiotic resistance gene-containing effluents originating from sites of varying antibiotic usage to the receiving environment.Methods: Gene abundance in effluents (municipal hospital and dairy farm) was compared against background samples of the receiving aquatic environment (i.e. the catchment source) to determine the resistome contribution of effluents. We used metagenomics and metatranscriptomics to correlate DNA and RNA abundance and identified differentially regulated gene transcripts.Results: We found that mean antibiotic resistance gene and transcript abundances were correlated for both hospital (ρ = 0.9, two-tailed P <0.0001) and farm (ρ = 0.5, two-tailed P  <0.0001) effluents and that two β-lactam resistance genes (blaGES and blaOXA) were overexpressed in all hospital effluent samples. High β-lactam resistance gene transcript abundance was related to hospital antibiotic usage over time and hospital effluents contained antibiotic residues.Conclusions: We conclude that effluents contribute high levels of antibiotic resistance genes to the aquatic environment; these genes are expressed at significant levels and are possibly related to the level of antibiotic usage at the effluent source.