Therapy for infections due to anaerobic bacteria: an overview.

Several classes of antimicrobial agents (e.g., penicillins, cephalosporins, tetracyclines, chloramphenicol, and clindamycin) are useful in treatment of infections due to anaerobic bacteria. However, certain anaerobic bacteria have shown a striking resistance to antimicrobial agents. In vitro susceptibility tests are useful for selection of optimal therapy. The choice of agent depends, to some extent, on the organisms responsible for the infection. Bacteroides fragilis is the most commonly encountered anaerobe, and it is also the most resistant to antimicrobial agents. Other factors influencing the selection of therapy include pharmacologic characteristics, degree of bactericidal activity, and toxicity. Proper therapy for anaerobic infections often requires intensive antimicrobial therapy for a prolonged period. Surgical intervention, including drainage of abscesses and excision of necrotic tissue, is important.