Microbiology of subphrenic abscesses: a 14-year experience.

The objective of the review was to study the aerobic and anaerobic microbiology of subphrenic abscesses in relation with predisposing conditions. A retrospective review of clinical and laboratory data of 52 patients treated between 1974 and 1988 was conducted. Forty-three (83%) patients developed the abscesses after an operative procedure. These included 11 patients after colonic, 9 patients after gastric or duodenal, 7 patients after abdominal trauma, 7 patients after biliary, and 6 patients after appendix surgery. A total of 194 organisms (3.7 isolates/specimen), 83 aerobic (1.6/specimen), and 111 anaerobes (2.1/specimen) were recovered. Aerobic bacteria only were recovered in 7 (13%) abscesses, anaerobic bacteria only in 11 (21%), and mixed aerobic and anaerobic bacteria in 34 (65%). Polymicrobial infection was present in 47 (90%). The predominant aerobic isolates were Escherichia coli (28 isolates), Enterococcus group D(9), and Staphylococcus aureus (9). The predominant anaerobes were Peptostreptococcus species (33 isolates), Bacteroides fragilis group (25), Clostridium species (13), and Prevotella species (6). The number of isolates/site varied. The number of anaerobic bacteria/site outnumbered or was equal to the number of aerobic or facultatives in all instances, except in abscesses after biliary surgery. Their number/site was especially high in abscesses after appendectomy, and the number of aerobic and anaerobic bacteria was the lowest after gastric or duodenal surgery. S. aureus predominated after gastric, duodenal and posttrauma surgery; B. fragilis predominated after colonic, appendix, and postabdominal trauma surgery; Enterococcus group D predominated after biliary surgery; Fusobacterium and Prevotella species predominated after gastric or duodenal surgery; and Clostridium species predominated after colonic or appendix surgery. These data highlight the polymicrobial aerobic-anaerobic nature of subphrenic abscesses and their correlation with predisposing surgery.