Biliary microbial colonization and antibiotic susceptibility in chronic calculous cholecystitis: a prospective observational study

Abstract

Background: One of the most common indications of cholecystectomy in the world is chronic calculous cholecystitis. Despite the fact that bile is physiologically sterile, gallstone disease predisposes microbial colonization by bile stasis, mucosal damage, and ascending infection. Bile microorganisms can be a contributor to infectious postoperative complications and affect the choice of perioperative antibiotics. Since there are regional differences in microbial flora and resistance to antibiotics, institution-specific data are required in evidence-based antimicrobial practice.

Methods: This was a prospective observational study design, based in a hospital and carried out on 87 patients who were undergoing cholecystectomy as a treatment of chronic calculous cholecystitis at a tertiary care centre in Uttar Pradesh after gaining ethical permission. Aseptically, intraoperative collection of about 2 ml of bile was done and subjected to regular microbiological procedures. The bacterium was identified using Gram staining and biochemical techniques after being cultured on blood agar and MacConkey agar. To determine antibiotic susceptibility, the Kirby-Bauer disc diffusion method was used in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines.

Results: Of the 87 patients who took part in the research, 70 (or 80.4% of the total) had cholecystectomy by laparoscopy, 12 (13.8%) had the procedure done openly, and 5 (5.8% of the total) had to have the procedure changed to open because laparoscopy failed. Biles were observed to be positive in 20 (23) patients, and sterile bile in 67 (77) patients. The most common isolate was Escherichia coli (45%), then Klebsiella pneumoniae (25%), then Enterococcus faecalis (15%), and Pseudomonas aeruginosa (15%). E. coli was more sensitive to cefuroxime and ciprofloxacin, and Klebsiella pneumoniae were intermediate to piperacillin-tazobactam and meropenem. Enterococcus faecalis was found to be sensitive to vancomycin and linezolid whereas Pseudomonas aeruginosa was found to be more sensitive to amikacin and piperacillin–tazobactam. Culture-positive patients had higher chances of postoperative wound infection, but this was not statistically significant.

Conclusion: Biliary microbial colonization was observed in about the quarter of patients with chronic calculous cholecystitis with Escherichia coli being the most common isolate. The high degree of antibiotic susceptibility variability underscores the need to have local antibiograms to optimize the use of antimicrobials during perioperative periods. Routine bile culture can be useful in the high-risk patients that undergo cholecystectomy who are selected.