Anaerobic bacteria in late infections following orthopedic surgery.

Twelve patients with late anaerobic infection following hip or knee arthroplasty or tibia osteosynthesis are presented. Peptococci (Peptococcus asaccharolyticus, P. magnus, P. prevotii) and peptostreptococci (Peptostreptococcus micros, P. anaerobius, P. parvulus) were present in nine of the cases. Anaerobic gram-positive or -negative rods were found in three cases (Propionibacterium acnes, Actinomyces israelii, and Bacteroides fragilis). Antibodies against the isolated bacteria were detected in sera of nine patients. Anaerobic bacteria seem to be responsible for some of the late reactions that may follow arthroplasty or osteosynthesis.