Microbiologic study of the bile culture and antimicrobial susceptibility in patients with biliary tract infection

BACKGROUND/AIMS: Bacterial infection of biliary tract may cause severe inflammatory response or sepsis. An immediate bile culture and appropriate antibiotic administration are important to control the biliary tract infection. The objective of the study was to identify organisms in bile and the features of antibiotic susceptibility in patients with biliary tract infection. METHODS: We retrospectively reviewed the clinical records of 212 patients whose bile had been cultured for variable biliary tract diseases at Inje University Ilsan Paik Hospital from Jan. 2000 to Feb. 2007. Bile samples were obtained from percutaneous transhepatic biliary drainage (PTBD, n=89), percutaneous transhepatic gallbladder drainage (PTGBD, n=14) or endoscopic naso-biliary drainage (ENBD, n=49). RESULTS: The overall positive rate of bile culture was 71.7% (152 cases). The organisms cultured were Escherichia coli (25.0%), Enterococcus spp. (13.4%), Klebsiella spp. (11.1%), Pseudomonas spp. (11.1%), and coagulase-negative Staphylococcus (9.7%) in decreasing order. Effective antibiotics for Gram-negative organisms were amoxicillin/clavulanic acid, amikacin, imipenem, and piperacillin/tazobactam in order of effectiveness. Of the cultured blood samples from 160 patients, fifty (31.2%) showed positive bacterial growth. The organisms isolated from blood were similar to those found in the bile. CONCLUSIONS: A broad spectrum penicillin/beta-lactamase inhibitor is a recommendable antimicrobial for empirical treatment for biliary tract infection. However, Gram-positive bacteria such as Enterococcus spp. or methicillin-resistant Staphylococcus aureus are emerging as causative microorganisms. If these organisms are isolated, antimicrobial drugs should be replaced by narrower-spectrum antimicrobials.