Raw dog food tested for antibiotic-resistant bacteria risks

Abstract

OBJECTIVE: To assess the potential contamination of commercial raw dog food products with bacteria of the Enterobacterales order that produce extended spectrum beta-lactamase (ESBL) and carbapenemase enzymes, determine risk factors for contamination, and understand isolate genetic diversity. SAMPLES: A total of 200 canine raw food products. METHODS: Products were cultured on selective chromogenic agar following enrichment steps. Whole-genome sequencing was performed for isolates that were confirmed to produce an ESBL. Isolates were characterized by antimicrobial resistance genes, and multilocus sequences typing, and compared to other isolates in the NCBI database for clonality. Preservation method and protein sources were assessed as potential risk factors for contamination with ESBL and carbapenemase-producing bacteria of the Enterobacterales order. RESULTS: No carbapenemase-producing Enterobacterales (CPE) were identified, but ESBL-producing Enterobacterales bacteria were isolated from 20/200 products (10.0%; 95% CI, 7.3 to 16.5%), all of which were frozen. Pork-derived protein source products were 8.1 times (P = .001; 95% CI, 2.53 to 26.2) more likely to carry ESBL-producing Enterobacterales bacteria than other protein sources. WGS analysis confirmed the presence of ESBL genes in a total of 25 distinct isolates (19 Escherichia coli, 5 Klebsiella pneumoniae, and 1 Citrobacter braakii). Genes encoding CTX-M type ESBL enzymes were the most common (24/25 isolates, 96.0%) with blaCTX-M-27 being the most common allele (8/25, 32.0%). CLINICAL RELEVANCE: Frozen, raw food products may serve as a route of transmission of ESBL-producing Enterobacterales bacteria to companion animals. Veterinarians should advise owners about the risks of raw food diets, including potential exposure to antimicrobial-resistant bacteria.