A prospective study of the microflora of nonpuerperal breast abscess.

The majority of reports concerning nonpuerperal breast abscess (NPBA) identify aerobic and facultative bacterial isolates as the predominant flora in this disease. In the present study, fine-needle aspiration was performed in 29 women with NPBA; 12 (41%) of the patients had a history of chronic NPBA. The mean age of patients was 39.2 years. The aspirated material was cultured both anaerobically and aerobically. A total of 108 bacterial strains were recovered from 32 specimens; two specimens yielded no bacterial growth. A mean of 3.6 different bacteria were recovered from each culture-positive specimen. Anaerobic recovery outweighed aerobic-facultative recovery by a factor of 2:1. Significantly, 37 strains (five aerobes and 32 anaerobes) were harvested only from enriched broth subcultured for four to 14 days after initial culture processing. Coagulase-negative staphylococci (60% of total aerobes) and peptostreptococci (47% of total anaerobes) were the predominant bacterial isolates. These findings indicate that NPBA is due to a mixed flora with a major anaerobic component. Furthermore, the results suggest that routine cultures often overlook the involvement of anaerobes in these infections.