PURPOSE. The methods of collecting, transporting, cultivating, and identifying aerobic bacteria in bone and joint infections have improved markedly since the early 1980s. In addition, many of the anaerobes have been reclassified and renamed. The purpose of this study was to provide more current information regarding the incidence of recovery of anaerobic bacteria from clinical specimens of infected bone and joint. MATERIALS AND METHODS: Specimens from 73 infected bone specimens and 65 infected joints inoculated on media supportive for aerobic and anaerobic bacteria showed bacterial growth. RESULTS: One hundred fifty-seven organisms (2.2 isolates/specimen), consisting of 122 anaerobic bacteria (1.7 isolates/specimen) and 35 facultative or aerobic bacteria (0.5 isolate/specimen), were recovered from the 73 bone specimens. Anaerobic bacteria were recovered with aerobe or facultative bacteria in 24 (33%) instances. The predominant anaerobes were Bacteroides species (49 isolates), anaerobic cocci (45), Fusobacterium species (11), Propionibacterium acnes (7), and Clostridium species (6). Conditions predisposing to bone infections were vascular disease, bites, contiguous infection, peripheral neuropathy, hematogenous spread, and trauma. Pigmented Prevotella and Porphyromonas species were mostly isolated in skull and bite infections (7 of 19), members of the Bacteroides fragtilis group in hand and feet infection (12 of 16), and Fusobacterium species in skull, bite, and hematogenous long bone infections. Seventy-four organisms (1.1 isolates/specimen), consisting of 67 anaerobic bacteria (1.0 isolate/specimen) and 7 facultative or aerobic bacteria (0.1 isolate/specimen), were isolated from 65 joint specimens. The predominant anaerobes were P. acnes (24 isolates), anaerobic cocci (17), Bacteroides species (10), and Clostridium species (5). Predisposing conditions to joint infection were trauma, prior surgery, presence of a prosthetic joint, and contiguous infection. P. acnes isolates were associated with prosthetic joints, members of the B. fragilis group with hematogenous spread, and Clostridium species with trauma. The clinical presentation of these cases is discussed. CONCLUSION: These data highlight the importance of anaerobic bacteria in bone and joint infection.
