BACTERIOLOGY OF BILIARY TREE

   Without biliary interventions, most bile is considered sterile. However, the presence of gall stones or biliary obstruction, the likelihood of bacterial contamination increases. Most bactbilia is caused by gram negative aerobes. Passage of bacteria upward from the duodenum into the biliary tree is a commonly held explanation for bacterial contamination.  Another route is through vasculature. A range of bacteria have been identified by culture or by PCR in the gall bladders of patients with cholecystitis and cholelithiasis (gallstones in the gall bladder), including Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Salmonella spp.,  Helicobacter spp.,  Enterobacter spp.,  Enterococcus spp.,  Pseudomonas aeruginosa, Bacteroides fragilis, Staphylococcus aureus, Proteus spp. and Acinetobacter spp