Veterinary Hospital Dissemination of CTX-M-15 Extended-Spectrum Beta-Lactamase–Producing Escherichia coli ST410 in the United Kingdom

We characterized extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) in 32 Escherichia coli extended spectrum cephalosporin (ESC)-resistant clinical isolates from UK companion animals from several clinics. In addition, to investigate the possible dissemination of ESBL clinical isolates within a veterinary hospital, two ESBL-producing E. coli isolates from a dog with septic peritonitis and a cluster of environmental ESC-resistant E. coli isolates obtained from the same clinic and during the same time period, as these two particular ESBL-positive clinical isolates, were also included in the study. Molecular characterization identified blaCTX-M to be the most prevalent gene in ESC-resistant isolates, where 66% and 27% of clinical isolates carried blaCTX-M-15 and blaCTX-M-14, respectively. The only PMQR gene detected was aac(6')-Ib-cr, being found in 34% of the ESC E. coli isolates and was associated with the carriage of blaCTX-M-15. The clinical and environmental isolates investigated for hospital dissemination had a common ESBL/AmpC phenotype, carried blaCTX-M-15, and co-harbored blaOXA-1, blaTEM-1, blaCMY-2, and aac(6')-Ib-cr. Multilocus sequence typing identified them all as ST410, while pulse-field gel electrophoresis demonstrated 100% homology of clinical and environmental isolates, suggesting hospital environmental dissemination of CTX-M-15-producing E. coli ST410.