Occurrence of Antimicrobial Resistance in Indicator Bacteria and Campylobacter spp. Isolated from Commercial Raw-Meat-Based Food for Dogs and Cats in Belgium

Background: Raw-meat-based diets (RMBDs) for companion animals have gained popularity but may serve as vehicles for antimicrobial-resistant (AMR) bacteria, posing risks to animal and public health. This study investigated the occurrence and risk factors of AMR in indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium) and Campylobacter spp. from commercial RMBD products. Methods: In 2023, 50 RMBD samples were collected in Belgium, representing 21 brands from five countries. After both selective and non-selective isolation and MALDI-TOF identification, antimicrobial susceptibility testing of the isolates was performed using broth microdilution. Results: From non-selective media, E. coli was found in 45 samples (90.0%), E. faecalis in 31 samples (62.0%), E. faecium in 23 samples (46.0%), and Campylobacter spp. in 3 samples (6.0%). Among these, one E. faecalis strain with acquired resistance to vancomycin and daptomycin was isolated. Multidrug resistance (MDR) was identified in 17 isolates from 15 samples (30.0%), including 14 MDR E. coli, 1 MDR E. faecalis, and 2 MDR E. faecium. From selective media, presumptive ESBL/AmpC-producing E. coli were detected in 17 samples (34.0%), and 5 E. faecium from linezolid-supplemented media were confirmed by the broth microdilution method. Samples from Belgian origin showed significantly higher E. faecium prevalence (76.5%) compared to Dutch samples (21.4%) (OR = 11.9, p < 0.001). Minor livestock sources were associated with increased MDR risk (OR = 5.52, p = 0.016). Conclusions: Commercial RMBDs in Belgium exhibit widespread bacterial contamination with concerning AMR patterns. These findings highlight the need for improved production standards in the RMBD industry and the need to raise awareness in pet owners.