103 research outputs found

    Dissemination of Multidrug-Resistant Bacteria into the Arctic

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    We show that Escherichia coli isolates originating from Arctic birds carry antimicrobial drug resistance determinants. This finding implies that dissemination of drug-resistant bacteria is worldwide. Resistance genes can be found even in a region where no selection pressure for resistance development exists

    High frequency of multiresistant respiratory tract pathogens at community level in South India

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    ObjectiveTo describe the patterns of antibiotic susceptibility of outpatient strains of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in the district of Pondicherry in South India.MethodsThe antibiotic susceptibilities of 94 S. pneumoniae, 97 H. influenzae and 104 M. catarrhalis strains, collected from outpatients with respiratory tract infections, were determined by disk diffusion and Etest.ResultsResistance or reduced susceptibility to trimethoprim–sulfamethoxazole was found in 67% of S. pneumoniae, 53% of H. influenzae and 24% of M. catarrhalis strains. Thirty-seven per cent of S. pneumoniae and 39% of H. influenzae strains were resistant or showed reduced susceptibility to tetracycline. Reduced susceptibility to penicillin was found in 6% of S. pneumoniae strains. Overall, 10% of S. pneumoniae and 38% of H. influenzae strains showed reduced susceptibility to ≥3 antibiotics. Comparisons between the antibiotic susceptibility patterns of the Indian strains and a corresponding collection of strains from Sweden indicate that the susceptibility of the native susceptible population is independent of geographic origin.ConclusionsThe findings indicate high consumption of tetracycline and trimethoprim–sulfamethoxazole in the area, which emphasizes the need for surveillance of the pattern of antibiotic susceptibility among respiratory tract pathogens at community level in developing countries and for the implementation of local guidelines for rational use of antibiotics

    Antimicrobial susceptibility testing of Bacteroides species by disk diffusion: The NordicAST Bacteroides study

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    Objectives - Antimicrobial susceptibility testing (AST) of anaerobic bacteria has until recently been done by MIC methods. We have carried out a multi-centre evaluation of the newly validated EUCAST disk diffusion method for AST of Bacteroides spp. Methods - A panel of 30 Bacteroides strains was assembled based on reference agar dilution MICs, resistance gene detection and quantification of cfiA carbapenemase gene expression. Nordic clinical microbiology laboratories (n = 45) performed disk diffusion on Fastidious Anaerobe Agar with 5% mechanically defibrinated horse blood (FAA-HB) for piperacillin-tazobactam, meropenem and metronidazole. Results - A total of 43/45 (95.6%) laboratories carried out disk diffusion per protocol. Intraclass correlation coefficients were 0.87 (0.80–0.93) for piperacillin-tazobactam, 0.95 (0.91–0.97) for meropenem and 0.89 (0.83–0.94) for metronidazole. For metronidazole, one media lot yielded smaller zones and higher variability than another. Piperacillin-tazobactam and meropenem zone diameters correlated negatively with cfiA expression. A meropenem zone diameter of Conclusions - Inter-laboratory agreement by disk diffusion was good or very good. The main challenges were media-related variability for metronidazole and categorical disagreement with the reference method for piperacillin-tazobactam in some cfiA-positive strains. An area of technical uncertainty specific for such strains may be warranted

    How to interpret MICs of antifungal compounds according to the revised clinical breakpoints v. 10.0 European committee on antimicrobial susceptibility testing (EUCAST)

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    Background EUCAST has revised the definition of the susceptibility category I from ‘Intermediate’ to ‘Susceptible, Increased exposure’. This implies that I can be used where the drug concentration at the site of infection is high, either because of dose escalation or through other means to ensure efficacy. Consequently, I is no longer used as a buffer zone to prevent technical factors from causing misclassifications and discrepancies in interpretations. Instead, an Area of Technical Uncertainty (ATU) has been introduced for MICs that cannot be categorized without additional information as a warning to the laboratory that decision on how to act has to be made. To implement these changes, the EUCAST-AFST (Subcommittee on Antifungal Susceptibility Testing) reviewed all, and revised some, clinical antifungal breakpoints. Objectives The aim was to present an overview of the current antifungal breakpoints and supporting evidence behind the changes. Sources This document is based on the ten recently updated EUCAST rationale documents, clinical breakpoint and breakpoint ECOFF documents. Content The following breakpoints (in mg/L) have been revised or established for Candida species: micafungin against C. albicans (ATU = 0.03); amphotericin B (S ≤/> R = 1/1), fluconazole (S ≤/> R = 2/4), itraconazole (S ≤/> R = 0.06/0.06), posaconazole (S ≤/> R = 0.06/0.06) and voriconazole (S ≤/> R = 0.06/0.25) against C. dubliniensis; fluconazole against C. glabrata (S ≤/> R = 0.001/16); and anidulafungin (S ≤/> R = 4/4) and micafungin (S ≤/> R = 2/2) against C. parapsilosis. For Aspergillus, new or revised breakpoints include itraconazole (ATU = 2) and isavuconazole against A. flavus (S ≤/> R = 1/2, ATU = 2); amphotericin B (S ≤/> R = 1/1), isavuconazole (S ≤ /> R = 1/2, ATU = 2), itraconazole (S ≤/> R = 1/1, ATU = 2), posaconazole (ATU = 0.25) and voriconazole (S ≤/> R = 1/1, ATU = 2) against A. fumigatus; itraconazole (S ≤/> R = 1/1, ATU = 2) and voriconazole (S ≤/> R = 1/1, ATU = 2) against A. nidulans; amphotericin B against A. niger (S ≤/> R = 1/1); and itraconazole (S ≤/> R = 1/1, ATU = 2) and posaconazole (ATU = 0.25) against A. terreus. Implications EUCAST-AFST has released ten new documents summarizing existing and new breakpoints and MIC ranges for control strains. A failure to adopt the breakpoint changes may lead to misclassifications and suboptimal or inappropriate therapy of patients with fungal infections

    Dissemination of Escherichia coli with CTX-M Type ESBL between Humans and Yellow-Legged Gulls in the South of France

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    Extended Spectrum beta-Lactamase (ESBL) producing Enterobacteriaceae started to appear in the 1980s, and have since emerged as some of the most significant hospital-acquired infections with Escherichia coli and Klebsiella being main players. More than 100 different ESBL types have been described, the most widespread being the CTX-M beta-lactamase enzymes (bla(CTX-M) genes). This study focuses on the zoonotic dissemination of ESBL bacteria, mainly CTX-M type, in the southern coastal region of France. We found that the level of general antibiotic resistance in single randomly selected E. coli isolates from wild Yellow-legged Gulls in France was high. Nearly half the isolates (47.1%) carried resistance to one or more antibiotics (in a panel of six antibiotics), and resistance to tetracycline, ampicillin and streptomycin was most widespread. In an ESBL selective screen, 9.4% of the gulls carried ESBL producing bacteria and notably, 6% of the gulls carried bacteria harboring CTX-M-1 group of ESBL enzymes, a recently introduced and yet the most common clinical CTX-M group in France. Multi locus sequence type and phylogenetic group designations were established for the ESBL isolates, revealing that birds and humans share E. coli populations. Several ESBL producing E. coli isolated from birds were identical to or clustered with isolates with human origin. Hence, wild birds pick up E. coli of human origin, and with human resistance traits, and may accordingly also act as an environmental reservoir and melting pot of bacterial resistance with a potential to re-infect human populations

    Multicentre testing of the EUCAST broth microdilution reference method for MIC determination on mycobacterium tuberculosis

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    Objectives: the first objective of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) subcommittee for antimycobacterial susceptibility testing (AMST), launched in 2016, was to set a reference method for determining the MICs of antituberculous agents, since many protocols are used worldwide and a consensus one is needed for the determination of microbiological breakpoints. Methods: during 2017 and 2018, MIC determination protocols were evaluated prospectively in a multicentre study within the four AMST laboratories. MIC results were obtained for isoniazid, levofloxacin and amikacin on the reference strain Mycobacterium tuberculosis H37Rv ATCC 27294. Broth microdilution (BMD) in Middlebrook 7H9 and solid medium dilution (SMD) in Middlebrook 7H10 were performed using two inoculum concentrations. MICs were interpreted with regard to visual and 99% inhibition after 7, 14 or 21 days of incubation for BMD and 21 days for SMD. Results: following the EUCAST reference protocol, intra- and inter-assay agreements were within ±1 MIC dilution for >95% of the observations for the three drugs in both methods. MIC values, presented as MIC mode (range) for BMD and SMD respectively, were: 0.03 (0.015-0.06) mg/L and 0.12 (0.06-0.25) mg/L for isoniazid, 0.25 mg/L (0.25-0.5) and 0.5 mg/L (0.12-0.5) for levofloxacin, and 0.5 mg/L (0.5-1.0) and 0.5 mg/L (0.5-1.0) for amikacin. Conclusions: both SMD and BMD were reproducible and eligible as a reference method for MIC determination of the Mycobacterium tuberculosis complex (MTBC). BMD was finally selected as the EUCAST reference method. From now on it will be used to set epidemiological cut-off values and clinical breakpoints of new and old antituberculous agents

    Antimicrobial susceptibility testing of mycobacterium tuberculosis complex isolates - the EUCAST broth microdilution reference method for MIC determination

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    Scope:Several methods are used worldwide for antibiotic susceptibility testing (AST) for theMycobac-terium tuberculosiscomplex (MTBC). The variability in the results obtained with these methods hamperssetting epidemiological cut-off (ECOFF) values and clinical breakpoints according to EUCAST guidelines.Methods for susceptibility testing and determination of the minimal inhibitory concentrations (MICs)need to be standardized for MTBC isolates for old and new agents. Our objective was to establish astandardized reference method for MIC determination for MTBC.Methods:The EUCAST antimycobacterial susceptibility testing subcommittee (AMST) compared pro-tocols of MIC determination with regard to medium, inoculum preparation, antituberculous agentpreparation, incubation, reading of the results and interpretation.Recommendations:The EUCAST reference method of MIC determination for MTBC is the broth micro-dilution method in Middlebrook 7H9-10% OADC medium. Thefinal inoculum is a 105CFU/mL suspension,obtained from a 10 2dilution of a 0.5 McFarland suspension prepared after vortexing bacterial colonieswith glass beads before suspending them in sterile water. The culture is maintained in a U-shaped 96-well polystyrene microtitre sterile plate with a lid incubated at 36 ±1 C. Reading is done using aninverted mirror as soon as the 1:100 diluted control (i.e. 103CFU/mL suspension) shows visual growth.The MIC, expressed in mg/L, is the lowest concentration that inhibits visual growth.MycobacteriumtuberculosisH37Rv ATCC 27294 is used as the reference strain and its targeted MIC values are within therange 0.03e0.12 for isoniazid, 0.12e0.5 for levofloxacin and 0.25e1 mg/L for amikacin.Conclusions:The EUCAST reference method for MTBC was endorsed by EUCAST after public consultationand will from now on be used to define EUCAST ECOFFs and clinical breakpoints. This reference methodis not primarily intended to be used under routine conditions and the AST methods will need to b

    Molecular Characterisation of Trimethoprim Resistance in Escherichia coli and Klebsiella pneumoniae during a Two Year Intervention on Trimethoprim Use

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    BACKGROUND: Trimethoprim resistance is increasing in Enterobacteriaceae. In 2004-2006 an intervention on trimethoprim use was conducted in Kronoberg County, Sweden, resulting in 85% reduction in trimethoprim prescriptions. We investigated the distribution of dihydrofolate reductase (dfr)-genes and integrons in Escherichia coli and Klebsiella pneumoniae and the effect of the intervention on this distribution. METHODOLOGY/PRINCIPAL FINDINGS: Consecutively isolated E. coli (n = 320) and K. pneumoniae (n = 54) isolates phenotypically resistant to trimethoprim were studied. All were investigated for the presence of dfrA1, dfrA5, dfrA7, dfrA8, dfrA12, dfrA14, dfrA17 and integrons class I and II. Isolates negative for the seven dfr-genes (n = 12) were also screened for dfr2d, dfrA3, dfrA9, dfrA10, dfrA24 and dfrA26. These genes accounted for 96% of trimethoprim resistance in E. coli and 69% in K. pneumoniae. The most prevalent was dfrA1 in both species. This was followed by dfrA17 in E. coli which was only found in one K. pneumoniae isolate. Class I and II Integrons were more common in E. coli (85%) than in K. pneumoniae (57%). The distribution of dfr-genes did not change during the course of the 2-year intervention. CONCLUSIONS/SIGNIFICANCE: The differences observed between the studied species in terms of dfr-gene and integron prevalence indicated a low rate of dfr-gene transfer between these two species and highlighted the possible role of narrow host range plasmids in the spread of trimethoprim resistance. The stability of dfr-genes, despite large changes in the selective pressure, indirectly suggests a low fitness cost of dfr-gene carriage
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