ABSTRACT
To better understand the prevalence of fluoroquinolone-resistant Escherichia coli among sheltered companion animals, we conducted a screening study of 38 dogs and 78 cats and investigated the resistance mechanisms and characteristics of the isolates. Fluoroquinolone-resistant E. coli was detected in 18 dogs (47.4â%) and 14 cats (17.9â%). The isolates carried one to four mutations in the gyrA, parC and parE genes of the quinolone resistance-determining region, and the number of mutations was proportional to the MIC for ciprofloxacin. For plasmid-mediated quinolone resistance, aac-(6')-Ib-cr was detected in nine isolates, qnrS in five isolates and qnrB in one isolate. A relationship between the presence of these genes and MIC for ciprofloxacin was not apparent. Statistical analysis indicated that fluoroquinolone-resistant E. coli was widely distributed among sheltered companion animals with various attributes. This may relate to the wide dissemination of fluoroquinolone resistance among humans and other animals in Japan.
ABSTRACT
PURPOSE: The prevalence of antimicrobial-resistant bacteria, especially cephalosporin-resistant Enterobacteriaceae, is a major concern for human and animal health. We investigated the prevalence of cephalosporin-resistant Enterobacteriaceae among sheltered dogs and cats with various backgrounds. METHOD: Faecal samples or rectal swabs were collected from 151 dogs and 182 cats, and screened for the presence of antimicrobial-resistant bacteria. Isolates were characterized phenotypically and genotypically by pulsed-field gel electrophoresis, multi-locus sequence typing and phylogenetic grouping. The animal attributes related to bacterial carriage were statistically analysed. RESULTS: Cephalosporin-resistant Enterobacteriaceae was detected in 22 dogs (14.6%) and 20 cats (11.0%): 21 were extended-spectrum ß-lactamase (ESBL)-producing, 20 were AmpC-producing, and 1 was both ESBL- and AmpC-producing. Their ß-lactamase genes were varied and associated with humans, animals or other origins. The genes CTX-M-14 (n=9) and CMY-2 (n=9) were dominant, but CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-15, CTX-M-24, CTX-M-27, CTX-M-55 and DHA-1 genes were also detected. Genotyping of isolates revealed that ß-lactamase-producing Enterobacteriaceae had high genetic diversity. Relationships between animals harbouring cephalosporin-resistant Enterobacteriaceae and individual attributes, such as sex and nutrition type, were detected, but there was no correlation between history of human association and the presence of the bacterium in either dogs or cats. CONCLUSION: We found several types of cephalosporin-resistant Enterobacteriaceae distributed among companion animals with a range of individual attributes and histories in Osaka, Japan. Companion animals may play a bridging role in the circulation of antimicrobial-resistant bacteria from humans and from other origins.