BILE CULTURE ISOLATES, ANTIMICROBIAL SUSCEPTIBILITY AND CLINICAL PROFILE IN A TERTIARY CARE HOSPITAL IN SOUTH INDIA: A RETROSPECTIVE STUDY

Abstract

Biliary tract infections are a frequent cause of sepsis in patients with biliary obstruction, and empirical therapy depends on local knowledge of the causative organisms and their resistance. This retrospective study describes the microbial isolates recovered from bile, their antimicrobial susceptibility, and the associated predisposing factors and complications in a tertiary care hospital in Mangalore, South India. All bile samples received from August 2015 to July 2016 were reviewed. Isolates were identified by conventional biochemical tests, and susceptibility was determined by disk diffusion. Of 161 bile samples, 108 (67.1%) showed significant growth. Escherichia coli was the most frequent isolate (30.9%), followed by Pseudomonas spp. (23.7%), Klebsiella spp. (17.3%) and Enterococcus spp. (9.4%). Susceptibility to cefotaxime was 4.7% in E. coli and 16.7% in Klebsiella spp., and extended-spectrum beta-lactamase producers of both organisms were detected. Imipenem and amikacin were the most active agents against E. coli (81.4% each) and Pseudomonas spp. (78.1% and 87.5%), and imipenem and cefoperazone/sulbactam against Klebsiella spp. (87.5% and 83.3%). However, 39.5% of E. coli and 33.3% of Klebsiella isolates were not susceptible to meropenem. All Enterococcus isolates were susceptible to vancomycin and teicoplanin. Among 75 patients with complete records, cholangitis was the most common diagnosis (50.7%), and cholelithiasis (45.3%), carcinoma (30.7%) and biliary stenting (29.3%) were the main predisposing factors; sepsis occurred in 4.0% and multiple organ dysfunction in 2.7%. Gram-negative bacilli with high resistance to third-generation cephalosporins predominated, and reduced carbapenem susceptibility was already evident. Routine bile culture with susceptibility testing, interpreted against current breakpoints, and continued local surveillance are needed to guide empirical therapy and antimicrobial stewardship.