Anaerobic bacteria in brain abscess, a review; observation of 18 consecutive cases.

The aerobic and anaerobic bacterial flora of 18 consecutive cases of brain abscesses were studied. Two cases were sterile. In five cases there was a single bacterial isolate. In five cases there was a single bacterial isolate the organism being Staphylococcus aureus in two cases, Bacteroides fragilis in two cases and Peptostreptococcus anaerobius in one case. In the remaining eleven cases, more than one organism was isolated. A combination of anaerobe with an aerobe was observed in five cases and infections with more than one anaerobe in as many as six cases. Anaerobic organisms are the important pathogens in brain abscess and occurrence of infections by more than one organism is a common factor.