Extended-spectrum β-lactamase-producing Enterobacteriaceae in healthy companion animals living in nursing homes and in the community.

Background: Animals could be reservoirs of extended-spectrum β-lactamases (ESBL) strains, but epidemiologic data on ESBL-producing bacteria in healthy pets are missing. We determined the prevalence of ESBL-producing Enterobacteriaceae in pets living in nursing homes and in households to investigate the potential role of companion animals as carriers of ESBL.

Methods: Three hundred seventy-six rectal swabs were taken from cats and dogs visiting or living in 68 randomly selected nursing homes or brought to 26 veterinary practices in Switzerland for routine mandatory vaccination. Isolates were identified by matrix-assisted laser desorption ionization time of flight mass spectrometry. Confirmatory tests were performed on the isolated Enterobacteriaceae. Phenotypic ESBL isolates were investigated for genetic determinants of resistance.

Results: The overall prevalence of ESBL isolates, adjusted for clustering, was 2.5% (95% confidence interval: 1.3-4.6). Pets that received an antibiotic treatment in the 3 months prior to the study had a higher risk to be carriers of these microorganisms (Adjusted odds ratio, 7.8; 95% confidence interval: 2.2-26.9).

Conclusion: ESBL-producing Enterobacteriaceae were present in healthy cats and dogs, particularly from those with a history of antibiotic treatment. These animals could become ESBL reservoirs. Investigations are needed to assess the possible transmission of these microorganisms between pets and humans.