Impact of Hospitalization and Antimicrobial Drug Administration on Antimicrobial Susceptibility Patterns of Commensal Escherichia Coli Isolated From the Feces of Horses

J Am Vet Med Assoc. 2006 Jun 15;228(12):1909-17. doi: 10.2460/javma.228.12.1909.


Objective-To evaluate antimicrobial susceptibility of commensal Escherichia coli strains isolated from the feces of horses and investigate relationships with hospitalization and antimicrobial drug (AMD) administration. Design-Observational study. Animals-68 hospitalized horses that had been treated with AMDs for at least 3 days (HOSP-AMD group), 63 hospitalized horses that had not received AMDs for at least 4 days (HOSP-NOAMD group), and 85 healthy horses that had not been hospitalized or treated with AMDs (community group). Procedures-Fecal samples were submitted for bacterial culture, and up to 3 E coli colonies were recovered from each sample. Antimicrobial susceptibility of 724 isolates was evaluated. Prevalence of resistance was compared among groups by use of log-linear modeling. Results-For 12 of the 15 AMDs evaluated, prevalence of antimicrobial resistance differed significantly among groups, with prevalence being highest among isolates from the HOSP-AMD group and lowest among isolates from the community group. Isolates recovered from the HOSP-AMD and HOSP-NOAMD groups were also significantly more likely to be resistant to multiple AMDs. Resistance to sulfamethoxazole and resistance to trimethoprim-sulfamethoxazole were most common, followed by resistance to gentamicin and resistance to tetracycline. Use of a potentiated sulfonamide, aminoglycosides, cephalosporins, or metronidazole was positively associated with resistance to 1 or more AMDs, but use of penicillins was not associated with increased risk of resistance to AMDs. Conclusion and Clinical Relevance-Results suggest that both hospitalization and AMD administration were associated with prevalence of antimicrobial resistance among E coli strains isolated from the feces of horses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use*
  • Cross Infection / veterinary
  • Drug Resistance, Bacterial*
  • Drug Resistance, Multiple, Bacterial
  • Escherichia coli / drug effects*
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / veterinary*
  • Feces / microbiology
  • Female
  • Horse Diseases / drug therapy*
  • Horse Diseases / microbiology
  • Horses
  • Hospitalization
  • Male
  • Microbial Sensitivity Tests / veterinary


  • Anti-Bacterial Agents