Pathogenic anaerobes.

Anaerobes are prevalent on all mucosal surfaces and virtually all anaerobic infections are endogenous. Two thirds of anaerobic infections involve five anaerobic organisms or groups--the Bacteroides fragilis group, the Bacteroides melaninogenicus-Bacteroides asaccharolyticus group, Fusobacterium nucleatum, the anaerobic cocci, and Clostridium perfringens. Conditions that lower the oxidation-reduction potential and disrupt the mucosal surface (eg, vascular problems, malignant neoplasms, and surgery) lead to infection with anaerobes. Clues to anaerobic infection include foul odor, gas, tissue destruction, underlying malignant neoplasms, and the unique appearance of certain anaerobes on Gram's stain. Specimens must be collected to avoid normal flora and transported to the laboratory under anaerobic conditions. Therapy involves surgical débridement and drainage and the use of various antimicrobial agents. Antimicrobial agents must be used for extended periods to avoid relapse.