Antimicrobial-resistant Enterobacteriaceae recovered from companion animal and livestock environments

Antimicrobial-resistant bacteria represent an important concern impacting both veterinary medicine and public health. The rising prevalence of extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase, carbapenemase (CRE) and fluoroquinolone-resistant Enterobacteriaceae continually decreases the efficiency of clinically important antibiotics. Moreover, the potential for zoonotic transmission of antibiotic-resistant enteric bacteria increases the risk to public health. Our objective was to estimate the prevalence of specific antibiotic-resistant bacteria on human contact surfaces in various animal environments. Environmental surface samples were collected from companion animal shelters, private equine facilities, dairy farms, livestock auction markets and livestock areas of county fairs using electrostatic cloths. Samples were screened for Enterobacteriaceae expressing AmpC, ESBL, CRE or fluoroquinolone resistance using selective media. Livestock auction markets and county fairs had higher levels of bacteria expressing both cephalosporin and fluoroquinolone resistance than did equine, dairy, and companion animal environments. Equine facilities harboured more bacteria expressing cephalosporin resistance than companion animal shelters, but less fluoroquinolone resistance. The regular use of extended-spectrum cephalosporins in livestock populations could account for the increased levels of cephalosporin resistance in livestock environments compared to companion animal and equine facilities. Human surfaces, as well as shared human and animal surfaces, were contaminated with resistant bacteria regardless of species environment. Detecting these bacteria on common human contact surfaces suggests that the environment can serve as a reservoir for the zoonotic transmission of antibiotic-resistant bacteria and resistance genes. Identifying interventions to lower the prevalence of antibiotic-resistant bacteria in animal environments will protect both animal and public health.