Background: Wound infections are typically mixed, with both anaerobic and non-anaerobic bacteria present and there are usually more anaerobes than aerobes (for example, in perforated or gangrenous appendicitis, we have found an average of 9 anaerobes and 3 aerobes). Many clinical laboratories do limited anaerobic bacteriology, using commercial kits based on inadequate phenotypic characteristics and inaccurate taxonomy. As a result, physicians and surgeons must treat wound infections empirically and tend to use drugs active against the most resistant anaerobes which leads to increased resistance to antimicrobials. Molecular techniques now available permit accurate and rapid characterization of microorganisms, both aerobic and anaerobic.