Evaluation of Rosco Neo‐Sensitabs for phenotypic detection and subgrouping of ESBL‐, AmpC‐ and carbapenemase‐producing Enterobacteriaceae
The increasing prevalence of ESBL‐, AmpC‐ and carbapenemase‐producing Enterobacteriaceae necessitates reliable phenotypic tests for detection and categorization. The main objective of this study was to evaluate ROSCO Neo‐Sensitabs with different β‐lactam‐β‐lactam inhibitor combinations for phenotypic detection and categorization of β‐lactamases in Enterobacteriaceae. Using standard CLSI/EUCAST methodology, differences in zones of inhibitions between a β‐lactam alone compared with the combination with a β‐lactamase inhibitor as well as subjective synergy observations were determined for 172 well characterized Enterobacteriaceae strains with defined resistance mechanisms. The results showed that for all ESBL‐positive strains (n = 66), combinations of clavulanic acid synergy with cefotaxime, ceftazidime or cefepime, were observed. All acquired AmpC β‐lactamases (n = 17) were detected using cloxacillin combined with cefotaxime and/or ceftazidime (both combinations were required). Carbapenemase producers (n = 59) with the exception of one KPC‐producer were correctly grouped using the combination of meropenem ± aminophenylboronic acid (APBA) or dipicolinic acid (DPA). Ethylene diamine tetraacetic acid (EDTA) also inhibited all metallo‐β‐lactamases, but as with DPA, one false positive result was observed. Based upon these data, we propose a tablet layout for 14 cm agar plates, which could be used as a whole or in a targeted approach for detection and categorizing of relevant acquired β‐lactamases in Enterobacteriaceae.
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Document Type: Research Article
Publication date: 2012-09-01