Canine raw meat diets and antimicrobial resistant E. coli: is there a link?

Abstract

Antimicrobial resistance is increasing amongst canine commensal and clinical bacteria. Risk factors for faecal carriage of AMR Escherichia coli have been reported, including the consumption of raw meat diets, however few studies have investigated dogs fed on such diets. This study aimed to determine the prevalence of AMR (resistance to at least one antimicrobial), multidrug resistant (MDR; resistance to three or more antimicrobial classes) and third generation cephalosporin resistant (3GCR) in canine faecal E. coli. The University of Liverpool Ethics Committee approved this study in March 2015. Faecal samples (n = 190) were obtained between May and July 2015 from dogs eating raw-meat (n = 114), or cooked meat (n = 76) diets. Selective and enrichment culture were used to detect bacteria and biochemical testing and PCR assays for the uidA gene were used to confirm identification. E. coli were tested for antimicrobial resistance by disc diffusion (CLSI 2013) to a range of antimicrobials (amoxicillin, amoxicillin- clavulanate, gentamicin, ciprofloxacin, chloramphenicol, tetracycline and trimethoprim sulfamethoxazole) and isolates from 3GCR impregnated agar plates (1 lg/ml ceftazidime and 1 lg/ml cefotaxime) were additionally tested for cefpodoxime resistance. AMR was significantly more likely to be detected in raw-fed compared to cookedmeat- fed dogs: 54% of dogs (95% CI: 45-64) compared to 17% (95% CI: 9-26) of dogs (P < 0.001). Furthermore MDR was also more likely in raw-fed 25% (95% CI: 17- 32) compared to 4% (95% CI: 0-8) of cooked-meat-fed dogs (P < 0.001). 3GCR E. coli was detected in 31% (95% CI: 22-39) of dogs that were raw-fed and only 4% (95% CI: 0-8) of dogs that were cooked-meat-fed dogs (P < 0.001). Raw-fed dogs may be a source of antimicrobial resistant E. coli for the household representing both a potential public health and animal welfare issue. Preventative measures need to be implemented to prevent dissemination of such bacteria.