Nonenteric Escherichia coli isolates from dogs: 674 cases (1990-1998)

To determine nonenteric sites associated with Escherichia coli isolates in dogs and the antimicrobial susceptibilities of the isolates.

Retrospective study.

17,000 canine specimens.

Medical records of 17,000 canine specimens submitted for bacteriologic culture were examined and the number of isolations of E coli was determined. For these cases, records were further examined with respect to body system involvement, sex, concurrent infection with other species of bacteria, and antimicrobial susceptibility.

674 E coli isolates (424 from urine, 62 from the skin, 52 from the respiratory tract, 45 from the ear, 43 from the female reproductive tract, 25 from the male reproductive tract, and 23 from other organ systems) were identified. There was a significantly higher proportion of isolates from urine specimens from spayed females than from sexually intact females or males. Escherichia coli was isolated in pure culture from 65.9% of the specimens. Most E coli isolates were susceptible to norfloxacin (90%), enrofloxacin (87.5%), gentamicin (90.7%), and amikacin (85.9%).

Most nonenteric E coli infections in dogs involve the urinary tract. Amikacin, gentamicin, norfloxacin, and enrofloxacin have the highest efficacy against canine E coli isolates. For E coli isolates from dogs, in vitro susceptibility to commonly used antimicrobial agents has remained fairly stable during the past decade.