Aerobic and anaerobic microbiology of infected hemorrhoids.

OBJECTIVES To study the aerobic and anaerobic microbiology of infected hemorrhoids. METHODS Retrospective review of the clinical microbiology records. RESULTS Aspirates of pus from infected hemorrhoids in 19 patients showed bacterial growth. Anaerobic bacteria only were recovered in six (32%) specimens, aerobic bacteria only in one (5%), and mixed aerobic and anaerobic bacteria in 12 (63%). Sixty-eight isolates were recovered: 39 anaerobes (2.1 isolates per specimen) and 29 aerobes (1.5 per specimen). The predominant anaerobes were Bacteroides sp. (13 isolates, including 10 Bacteroides fragilis groups) and 13 Peptostreptococcus sp. The predominant aerobes were Escherichia coli (7), Proteus sp. (5), group D streptococci (4), and Pseudomonas sp. (3). CONCLUSIONS This study highlights the polymicrobial nature and predominance of anaerobic bacteria in infected hemorrhoids.