Enrofloxacin resistance in Escherichia coli isolated from dogs with urinary tract infections

Objective - To assess the strain heterogeneity of enrofloxacin-resistant Escherichia coli associated with urinary tract infections in dogs at a veterinary medical teaching hospital (VMTH). In addition, strains from other veterinary hospitals in California were compared with the VMTH strains to assess the geographic distribution of specific enrofloxacin-resistant E coli isolates. Design - Bacteriologic study. Sample Population - 56 isolates of E coli from urine samples (43 isolates from dogs at the VMTH, 13 isolates from dogs from other veterinary clinics in California). Procedures - Pulsed field gel electrophoresis was performed on 56 isolates of E coli from urine samples from 56 dogs. All 56 isolates were tested for susceptibility to amoxicillin, chloramphenicol, enrofloxacin, tetracycline, trimethoprim-sulphamethoxazole, cephalexin, and ampicillin. Enrofloxacin usage data from 1994 to 1998 were obtained from the VMTH pharmacy. Results - Several strains of enrofloxacin-resistant E coli were collected from urine samples from the VMTH, and strains identical to those from the VMTH were collected from other veterinary clinics in California. For the isolates that did share similar DNA banding patterns, variable antibiotic resistance profiles were observed. Conclusions and Clinical Relevance - The increased occurrence of enrofloxacin-resistant E coli from urine samples from dogs at the VMTH was not likely attributable to a single enrofloxacin-resistant clone but may be attributed to a collective increase in enrofloxacin resistance among uropathogenic E coli in dogs in general.