Contamination With Antimicrobial-Resistant Escherichia coli, Salmonella, and Enterococcus in Raw Meat-Based Diets for Pets.

Abstract

Raw meat-based diets (RMBDs) for pets, which contain raw meat from livestock, aquatic species, or wild-captive animals, are known to harbour feed-borne pathogens and antimicrobial-resistant (AMR) bacteria. This study investigated the contamination of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, Salmonella, Enterococcus faecalis, and E. faecium in Thai RMBD products, focusing on their AMR phenotypic and genotypic properties. A total of 50 RMBD samples and five fresh-cooked diets (FCDs) were analysed for total aerobic colony counts (ACC) and the presence of third-generation cephalosporins (3GC)-resistant E. coli, Salmonella, E. faecalis, and E. faecium. The AMR phenotypes of isolated bacteria were determined using antimicrobial susceptibility testing and ESBL production, while blaCTX-M and mcr genes were detected by PCR assays. ACCs in RMBD samples were higher than those in FCD samples. The RMBD products tested positive for 3GC-resistant E. coli (n = 40, 80.0%), Salmonella spp. (n = 35, 70.0%), E. faecalis (n = 50, 100%), and E. faecium (n = 42, 84.0%). All 3GC-resistant E. coli isolates were ESBL producers carrying blaCTX-M group 1 and group 9. Among the Salmonella isolates, five ESBL-producing S. Infantis isolates carried blaCTX-M group 9. Two ESBL-producing E. coli and seven Salmonella isolates exhibited colistin resistance. No vancomycin resistance was observed in the enterococcal isolates. These findings underscore the high prevalence of Salmonella and ESBL-producing E. coli in RMBD products, emphasising the potential health risks associated with RMBD consumption for pets. This study highlights the need for awareness and preventive measures to mitigate AMR spread through pet foods.