Microbiology of bile in patients with cholangitis or cholestasis with and without plastic biliary endoprosthesis

Background: Cholangitis is a frequent complication of biliary stents. Empiric antibiotic selection is primarily based on bile cultures obtained from patients undergoing surgery and few data are available with respect to ERCP and billary stents. This study analyzed the microbiology of bile and the antibiotic sensitivities of the organisms identified in patients presenting with clinical cholangitis or cholestasis. Methods: All bile cultures collected during ERCP from January 1994 to January 2000 were identified by using an ERCP database. Results: One hundred eighty cultures from 160 patients (mean age 55 years, range 6-94 years) were identified. Sixty-nine specimens were collected at ERCPs performed in patients with no biliary stent in place (group 1). One hundred eleven specimens were obtained from patients with a biliary stent in situ (group 2). The primary diagnoses for patients in groups 1 and 2 were as follows, respectively: malignant bile duct obstruction (25 and 85), choledocholithiasis (16 and 2), benign biliary strictures (6 and 18), acquired immunodeficiency syndrome (8 and 0), and miscellaneous (114 and 6). There were 38 positive bile cultures in group 1 (55%) and 109 positive cultures in group 2 (98%; p< 0.05). A higher frequency of polymicrobial infections (90%) was found in group 2 patients (vs. group 1, 45%; p < 0.001). Escherichia coli was the most common organism found in group 1 (17%); Enterococcus the most common in group 2 (31%). Among patients with positive bile cultures, bacteremia was more frequent in group 2 patients (46% vs. 21%; p < 0.05). Ciprofloxacin and cefiriaxone were the most effective antibiotics against identified gram-negative bacilli, and vancomycin against Enterococci. Conclusion: In patients with cholangitis associated with biliary obstruction, the antibiotic selected initially should be active against gram-negative bacilli. Use of quinolones is recommended because these agents effectively penetrate an obstructed biliary tree and can be administered orally. Enterococci and polymicrobial infections are found more commonly in patients with a biliary stent than those without a stent. Pending definitive biliary decompression, patients with sepsis and those who do not quickly respond to treatment with a quinolone may benefit from the addition of antibiotic coverage against gram-positive organisms, targeted against Enterococci.