Prevalence of AmpC- and Extended-Spectrum β-Lactamase-Harbouring Enterobacteriaceae in Faecal Flora of a Healthy Domestic Canine Population.

In order to estimate the prevalence of AmpC- and ESBL β-lactamase-producing Enterobacteriaceae in the faecal flora of a healthy domestic canine population, faecal samples were obtained from healthy dogs receiving routine parasitology screening at the Ohio State University Veterinary Medical Center, between January 2013 and April 2013. Samples were screened for the presence of AmpC and ESBL β-lactamase phenotypes, and the clinically important genotypes, blaCMY and blaCTX -M , were confirmed via conventional PCR. Minimum inhibitory concentrations were determined for isolates and plasmids were characterized. Two hundred and twelve canine faecal samples were screened, of which 30 harboured isolates carrying the AmpC blaCMY , representing 14.2% of the population (95% CI: 9.4-18.9%). Nine samples harboured isolates that carried the ESBL blaCTX -M , representing 4.2% of the population (95% CI: 1.5-7.0%). Isolates containing blaCMY harboured multiple plasmid replicon types, while isolates containing blaCTX -M harboured few plasmid replicon types. Our results suggest that domestic dogs may serve as a reservoir for extended-spectrum cephalosporin resistance genes for other domestic animal populations as well as for their human companions. This represents a potential veterinary and public health risk that warrants further investigation and continued surveillance to ascertain the nature and extent of the risk. The high level of diversity of plasmid content among isolates harbouring blaCMY suggests broader dissemination relative to blaCTX -M isolates.