Aerobic and anaerobic microbiology of biliary tract disease.

A retrospective analysis of the experiences of two military hospitals over 4 years in the recovery of organisms from biliary tract specimens was done. Bacterial growth was obtained in 123 bile specimens. Aerobic and facultative bacteria only were present in 59 specimens (48%), aerobic bacteria only were present in 4 specimens (3%), and mixed anaerobic and aerobic or facultative bacteria were present in 60 specimens (49%). Of 286 isolates recovered, 216 were aerobic or facultative (1.8 per specimen) and 70 were anaerobic (0.6 per specimen). The predominant bacteria were Escherichia coli (71 isolates), group D streptococci (42 isolates), Klebsiella sp. (29 isolates), Clostridium sp. (27 isolates), Bacteroides sp. (28 isolates), and Enterobacter sp. (16 isolates). Polymicrobial infections were present in 108 instances (88%). A higher recovery rate of anaerobes was present in patients with chronic infections than in those with acute infections and did not correlate with the presence of gallstones or use of antimicrobial prophylaxis.