RESUMO
The surveillance of antimicrobial resistance among humans and food-producing animals is important to monitor the zoonotic transmission of multidrug-resistant bacteria (MDRB). We assessed the prevalence of four MDRB within the meat production chain, including extended-spectrum ß-lactamase (ESBL)-producing, carbapenemase-producing Enterobacterales (CPE) and colistin-resistant Enterobacterales (Col-E), as well as vancomycin-resistant enterococci (VRE). In total, 505 samples from four stages of meat production, i.e., slaughterhouses, meat-processing plants, fresh food products and the urban environment, were collected in northwestern Germany in 2018/2019 and screened for the presence of MDRB using both culture-based and PCR-based techniques. We detected genes encoding for carbapenemases in 9-56% (blaOXA-48, blaKPC, blaNDM, blaVIM) and colistin resistance-encoding mcr genes in 9-26% of the samples from all stages. Culture-based analysis found CPE and VRE only in environmental samples (11% and 7%, respectively), but Col-E and ESBL-producers in 1-7% and 12-46% of samples from all stages, respectively. Overall, our results showed that ESBL-producers and mcr-carrying Col-E were common in food-producing animals at slaughterhouses, in meat-processing plants and in food items at retail, while CPE and VRE were only found in the environment. The discrepancy between detected carbapenemase genes and isolated CPE emphasizes the need for more sensitive detection methods for CPE monitoring.
RESUMO
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 determined CPE detection rate, we recommend the use of McC+CTX+MEM for monitoring purposes. This study indicates that the use of ChromID® CARBA agar might lead to an underestimation of the current CPE occurrence in food and livestock samples.
RESUMO
The objective of this study was to investigate the prevalence of methicillin-resistant Staphylococcus aureus on different stages of a fresh pork production chain to reveal potential carryover from live animals to meat. Samples were collected at different stages of the production process in a large German abattoir with an integrated processing unit for fresh pork. Samples included nasal swabs from pigs at stunning, environmental samples from the slaughter line, surface samples from carcasses, environmental and meat samples from the processing unit, and samples from final products. Samples were analyzed with an established two-step selective enrichment method, and isolates were characterized with respect to their S. aureus protein A gene (spa) and staphylococcal cassette chromosome mec (SCCmec; which harbors the mecA gene) types. Contamination rate was highest (64.7%) in nasal swabs and lower (6.0%) on carcasses, meat at processing (4.2%), and final products (2.8%). Environmental samples were positive along the slaughter line (12%) but not in the processing unit. spa types t011 and t034 and SCCmec type V predominated the isolates. Heterogeneity of spa types was highest in nasal swabs. Results show that methicillin-resistant S. aureus can be identified at all stages of the production chain. Further studies are needed to identify potential control points to reduce the carryover from farm animals to the final products.
