Organisms isolated from dogs and cats with anaerobic infections and susceptibility to selected antimicrobial agents

Abstract

Objective: To determine the prevalence of obligate anaerobic bacteria in bacterial infections in dogs and cats and susceptibility to selected antimicrobial agents.

Design: Case series.

Sample population: Specimens from 1,267 dogs and 243 cats.

Procedure: Standard anaerobic and aerobic bacterial culture methods were used. Anaerobic isolates were tested for susceptibility to selected antimicrobial agents.

Results: Obligate anaerobic bacteria were isolated from 199 (15.7%) and 69 (28.4%) specimens obtained from dogs and cats, respectively. More than half of the specimens that contained obligate anaerobic bacteria were from draining tracts (exclusively dogs), pleural fluid, abscesses, bones, the respiratory tract, or the abdominal cavity. The most commonly isolated obligate anaerobic bacteria (approx 70% of all isolates) were Bacteroides spp, Peptostreptococcus spp, Fusobacterium spp, and Porphyromonas spp. Eighty percent of the specimens that contained obligate anaerobic bacteria also contained facultative anaerobic or aerobic organisms. The organisms most commonly isolated in association with obligate anaerobic bacteria were members of the family Enterobacteriaceae (Escherichia coli was the most common), Pasteurella spp, and Staphylococcus intermedius. Ninety-seven obligate anaerobic isolates were tested for susceptibility to ampicillin, amoxicillin-clavulanic acid, chloramphenicol, clindamycin, and metronidazole. All were susceptible to amoxicillin-clavulanic acid and chloramphenicol, and most were susceptible to metronidazole. Only 71% of the Bacteroides isolates were susceptible to ampicillin, and only 83% were susceptible to clindamycin. Only 80% of the Clostridium isolates were susceptible to clindamycin, but all were susceptible to ampicillin.

Clinical implications: Data on sites and conditions from which anaerobic bacteria are commonly isolated, along with results of susceptibility testing, may be useful in designing antimicrobial treatment regimens.