A retrospective study was conducted to characterize the prevalence, identity, and antimicrobial susceptibility of common hepatobiliary isolates from dogs and cats with suspected hepatobiliary disease. Results for all bacterial cultures performed on canine and feline liver tissue, gallbladder tissue, and bile samples over a 5-year period were compiled from the database of the microbiology laboratory at the University of Wisconsin Veterinary Medical Teaching Hospital. All cases included in this data compilation had clinical findings consistent with primary or secondary hepatobiliary disease, including increased liver enzyme activity, decreased serum albumin concentration, hyperbilirubinemia, increased serum bile acid concentrations, abnormal hepatobiliary findings on ultrasonography, or suspicion of hepatic involvement of systemic neoplasia. Hepatic cultures from cats were more commonly positive than those from dogs, and infections in cats usually involved a single species of bacteria. Biliary cultures for both dogs and cats produced a significantly higher percentage of positive results than did hepatic cultures, suggesting that the biliary system may be more susceptible to bacterial infection or may be a more sensitive site to document hepatobiliary infection. Findings of this study further indicated that the predominant pathogens involved in hepatobiliary infections in dogs and cats are enteric bacteria. Nearly all of the aerobic bacteria were susceptible to ciprofloxacin, and numerous isolates of Escherichia coli were resistant to amoxicillin/clavulanate and first-generation cephalosporins. All anaerobic gram-negative rods tested, primarily species of Bacteroides, were found to be beta-lactamase positive.

COMMENTARY: Although we have known that aerobic enteric bacteria can be associated with hepatobiliary disease, this study demonstrates that anaerobes are also prevalent in hepatobiliary disease. Combination therapy of a fluoroquinolone and amoxicillin/clavulanic acid with or without metronidazole is appropriate, particularly in cats, in which hepatobiliary infections may be more common.

Bacterial culture results from liver, gallbladder, or bile in 248 dogs and cats evaluated for hepatobiliary disease: 1998-2003. Wagner KA, Hartmann FA, Trepanier LA.J Vet Intern Med 21:417-424, 2007.