Background: Extraintestinal infections caused by multidrug-resistant (MDR) Escherichia coli and Enterobacter are becoming more common in veterinary medicine.
Objective: To generate hypotheses for risk factors for dogs acquiring extraintestinal infection caused by MDR E. coli and Enterobacter, describe antimicrobial resistance profiles and analyze treatment and clinical outcomes.
Animals: Thirty-seven dogs diagnosed with extraintestinal infection caused by MDR E. coli and Enterobacter spp. between October 1999 and June 2006.
Methods: Retrospective case series assembled from hospital records data, including clinical history before 1st MDR isolation and treatment outcome. Identity and antimicrobial susceptibility profiles were confirmed by standard microbiological techniques for 57 isolates.
Results: Most dogs had an underlying disease condition (97%), received prior antimicrobial treatment (87%), were hospitalized for >or =3 days (82%), and had a surgical intervention (57%). The urinary tract was the most common infection site (62%), and urinary catheterization, bladder stasis, or both were common among dogs (24%). Some dogs were treated with high doses of co-amoxyclavulanate (n = 14) and subsequently recovered even though the isolates showed in vitro resistance to this antimicrobial. Other dogs were successfully treated with chloramphenicol (n = 11) and imipenem (n = 2).
Conclusion and clinical importance: Predisposing disease condition, any prior antimicrobial use rather than a specific class of antimicrobial, duration of hospitalization, and type of surgical procedure might be risk factors for acquiring MDR extraintestinal infections. Whereas culture and sensitivity results can indicate use of last-resort antimicrobials such as imipenem for MDR infections, some affected dogs can recover after administration of high doses of co-amoxyclavulanate.