Microbiology of choledochal bile in patients with choledocholithiasis admitted to a tertiary hospital

Aim: The present study was designed to investigate the microbiology of choledochal bile of patients with cholangitis and choledocholithiasis. Methods: We identified and determined the antimicrobial susceptibility of bacteria isolated in the bile of patients with cholangitis and choledocholithiasis diagnosed by endoscopic retrograde cholangiopancreatography (ERCP). Results: Nineteen (82.6%) of 23 patients with choledocholithiasis had positive bile cultures. A single agent was detected in 11 patients (57.9%), while a mixed growth, with pathogens ranging from two to three species, were seen in eight patients (42.1%). Patients with clinical manifestations of cholangitis had significantly higher counts of colonies per mL of bile (> 105 cfu/mL).The predominant Gram‐negative aerobic bacteria isolated were Escherichia coli (9, 31.0%), Klebsiella pneumoniae (5, 17.2%), Enterobacter cloacae (2, 6.9%), Pantoea agglomerans (1, 3.4%), and Pseudomonas aeruginosa (1, 3.4%). The predominant Gram‐positive bacteria were Enterococcus faecalis (5, 17.2%) and Streptococcus sp. (5, 17.2%). Bacteroides fragilis was isolated in one patient with mixed growth. All Gram‐positive bacteria isolated in bile were sensitive to ampicillin, and all Gram‐negative bacteria isolated were sensitive to gentamicin with a minimum inhibitory concentration (CIM90) ranging from 0.5 to 1.0‐µg/mL. Gram‐negative bacteria were also sensitive to imipenem, fluorquinolones, second and third generation cephalosporins. Although all five isolates of E. faecalis were sensitive to ampicillin, two of five (40%) E. faecalis isolates demonstrated high levels of resistance to gentamicin. Conclusion: E. coli, K. pneumoniae, E. faecalis and Streptoccocus sp. were the most common bacteria isolated in the bile of patients with cholangitis and choledocholithiasis, which were sensitive to a simple therapeutic regimen, such as the combination of ampicilin and gentamicin.