Anaerobic infections in surgery: clinical review

Anaerobic bacteria are being recognized with increasing frequency as important micro-organisms in surgical infections. Clostridium, Bacteriodes, Fusobacterium, and Peptostreptococcus are the clinically prominent pathological anaerobes. All are commensals and, consequently, most anaerobic infections are endogenous in origin. In the colon, anaerobes are 1,000 times more prevalent than aerobes. This has important implications regarding the management of gastrointestinal tract operations and the treatment of infections originating from the bowel. Typical anaerobic infections include gas gangrene, brain abscess, oral infections, putrid lung abscesses, intra-abdominal abscesses, and wound infections following gynecologic and bowel surgery, perirectal abscesses, postabortal infections, and septic thrombophlebitis. Infections with anaerobic organisms must be suspected when there is feculent odor and/or gas production following gynecologic or bowel surgery, when there are organisms on gram staining but no growth on aerobic cultures, or when septicemia is associated with repeatedly negative blood cultures. Debridement and drainage constitute the main stay of treatment. All anaerobes are sensitive to chloramphenicol and clindamycin and all but Bacteroides fragils are sensitive to penicillin. Identification of anaerobes requires proper specimen sampling, immediate culturing on prereduced media, and careful gram staining of clinical material. The frequency of anaerobic organisms in surgical infections generally is not recognized by many surgeons; their importance needs to be stressed in the future.