The infected tissues usually contain a mixture of several kinds of anaerobes and frequently also contain aerobic and facultative bacteria. Abscesses, postoperative wound infections, and generalized peritonitis produced by anaerobes occur as a consequence of bowel perforation during surgery or injury. Anaerobic lung infections may originate in the bronchi or the blood. Aspirations from the upper respiratory tract, which contain large numbers of anaerobic bacteria, are responsible for initiating infection in the bronchi. Anaerobic infections of the vagina and uterus sometimes occur after gynecologic surgery or in association with malignancy of pelvic organs.
Anaerobes infrequently produce meningitis, but are a common cause of brain abscesses.
The infecting organisms usually originate in the upper respiratory tract. Skin and soft tissue infections. Combinations of anaerobes, aerobes, and facultative organisms often act synergistically to produce these infections. Oral and dental infections. These local infections frequently extend to the face and neck and sometimes to other areas of the body such as the brain.