Obligate anaerobes in clinical veterinary practice.

Clinical specimens obtained from domestic animals were examined to determine the relative prevalence of obligate anaerobic bacteria and the species represented. Of 3,167 samples cultured anaerobically as well as aerobically, 2,234 were bacteriologically positive. Of these positive samples, 583 (26%) contained species of obligate anaerobic bacteria in a total of 641 isolates. Most positive samples contained anaerobes admixed with aerobic species, although 6% of such samples yielded pure cultures of obligate anaerobes. The most common sites from which anaerobes were isolated were abscesses (32% of abscesses cultured contained species of obligate anaerobes), peritoneal exudates (24%), and pleural effusions (20%). Bacteroides melaninogenicus, Bacteroides spp., Peptostreptococcus anaerobius, and Bacteroides ruminicola accounted in the aggregate for approximately 50% of all anaerobic isolates. Bacteroides fragilis accounted for 1% of all the isolates, and members of the genus Clostridium accounted for 8%.