Suchergebnisse

Due to the increasing reports of carbapenemase-producing Enterobacteriaceae (CPE) from livestock in recent years, the European Reference Laboratory for Antimicrobial Resistances (EURLAR) provided a protocol for their recovery from caecum and meat samples. This procedure exhibited limitations for the detection of CPE with low carbapenem MIC values. Therefore, it was modified by a second, selective enrichment in lysogeny broth with cefotaxime (CTX 1 mg/L) and with meropenem (MEM 0.125 mg/L) at 37 C under microaerophilic conditions. By Real-time PCR, these enrichments are pre-screened for the most common carbapenemase genes. Another adaptation was the use of in-house prepared MacConkey agar with MEM and MEM+CTX instead of commercial selective agar. According to the EURL-method, we achieved 100% sensitivity and specificity using the in-house media instead of commercial agar, which decreased the sensitivity to ~75%. Comparing the method with and without the second enrichment, no substantial influence on sensitivity and specificity was detected. Nevertheless, this enrichment has simplified the CPE-isolation regarding the accompanying microbiota and the separation of putative colonies. In conclusion, the sensitivity of the method can be increased with slight modifications. ; This work was financially supported by a grant of the German Federal Institute for Risk Assessment (43-001 and 43-002). The work of Natalie Pauly was supported by the European Joint Project (EJP) IMPART funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 773830. The work of Stefan Schwarz is supported by the German Federal Ministry of Education and Research (BMBF) under project number and 01KI2009D as part of the Research Network Zoonotic Infectious Diseases.

After first detections of carbapenemase-producing Enterobacteriaceae (CPE) in animals, the European Union Reference Laboratory for Antimicrobial Resistance has provided a protocol for the isolation of carbapenemase-producing Escherichia (E.) coli from cecum content and meat. Up to now, only few isolates were recovered using this procedure. In our experience, the choice of the selective agar is important for the efficacy of the method. Currently, the use of the prevailing method fails to detect CPE that exhibit a low resistance against carbapenems. Thus, this study aims to evaluate the suitability of selective media with antibiotic supplements and commercial ChromID(®) CARBA agar for a reliable CPE detection. For comparative investigations, detection of freeze-dried carbapenemase-resistant bacteria was studied on different batches of the ChromID(®) CARBA agar as well as on MacConkey agar supplemented with 1 mg/L cefotaxime and 0.125 mg/L meropenem (McC+CTX+MEM). The suitability of the different media was assessed within a time of 25 weeks, starting at least six weeks before expiration of the media. Carbapenem-resistant isolates exhibiting a serine-based hydrolytic resistance mechanism (e.g., bla(KPC) genes) were consistently detected over 25 weeks on the different media. In contrast, carbapenemase producers with only slightly reduced susceptibility and exhibiting a zinc-catalyzed activity (e.g., bla(VIM), bla(NDM), and bla(IMP)) could only be cultivated on long-time expired ChromID(®) CARBA, but within the whole test period on McC+CTX+MEM. Thus, ChromID(®) CARBA agar appears to be not suitable for the detection of CPE with slightly increased minimum inhibitory concentrations (MIC) against carbapenems, which have been detected in German livestock and thus, are of main interest in the national monitoring programs. Our data are in concordance with the results of eleven state laboratories that had participated in this study with their ChromID(®) CARBA batches routinely used for the German CPE monitoring. Based on the ...