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.

To investigate the prevalence of types of meticillin-resistant Staphylococcus aureus (MRSA) in slaughter pigs in German abattoirs, nasal swabs were collected from a total of 1026 pigs in five abattoirs after stunning in the course of two studies, and examined for MRSA. Study 1 included four abattoirs; study 2 was carried out in one large abattoir. Isolates were tested for antimicrobial susceptibility and characterised using spa-typing, multilocus sequence typing (MLST) and typing of the staphylococcal cassette chromosome, SCCmec. Overall, MRSA was isolated from 70.8 per cent of 520 samples in study 1 and from 49.0 per cent of 506 samples in study 2. The proportion of positive samples varied substantially between the abattoirs in study 1. Most isolates belonged to spa-types t011 and t034 and SCCmec types III and V. MLST of selected isolates revealed that they were all MLST ST398. Besides beta-lactams, 100 per cent of the isolates were resistant to tetracycline, 80.5 per cent were resistant to erythromycin and 80.7 per cent were resistant to clindamycin. Less than 5 per cent of the isolates were resistant to other antimicrobials.

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 β-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.

Validation of Selective CPE Agar Our data are in concordance with the results of eleven state laboratories that had participated in this study with their ChromID R 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 R CARBA agar might lead to an underestimation of the current CPE occurrence in food and livestock samples.

The aim of this study was to support a risk assessment of MRSA-isolates from swine using a diagnostic DNA-microarray to detect virulence-, toxin-and resistance related genes. In comparison with other species like poultry, cattle and humans there were only few isolates with virulence genes.