Microbial Flora in Gallstones: A Prospective Observational Study of Cholecystectomy Patients

Introduction: Gallstone disease is a common cause of morbidity worldwide, with numerous studies suggesting the role of bacteria in the pathogenesis of gallstone formation and in infective complications arising from stones lost in the peritoneal cavity post-surgery. Although molecular and microscopy methods can detect the presence of bacteria, they do not provide information about the infectious potential of the microorganisms. Aim: To analyse the bacteriological profile of gallstones in patients with cholelithiasis undergoing open or laparoscopic cholecystectomy. Materials and Methods: A prospective observational study was conducted on patients undergoing cholecystectomy for symptomatic cholelithiasis from February 2024 to May 2025 in the Departments of Surgery and Microbiology at a tertiary care hospital in Central Maharashtra (Chhatrapati Sambhajinagar), India. The study included 76 patients undergoing open or laparoscopic cholecystectomy for acute, chronic, or acute-onchronic cholecystitis. Demographic details like age and gender were recorded, along with clinical presentation, intraoperative findings, and co-morbidities. Post-cholecystectomy, gallstones were aseptically collected and subjected to culture and sensitivity testing. Positive cultures were further processed for identification and susceptibility using the Vitek 2 system, while negative cultures were reported after five days of incubation. Results: The peak incidence in females was observed in the 41-60 years age group (20 cases, 26.3%), whereas in males it was observed in the 61-80 years age group (23 cases, 30.3%). Culture positivity was observed in 49 gallstones (64.5%). Enteric bacteria predominated amongst the isolates, with Escherichia coli (E. coli) being the most common (18 cases, 31.57%), followed by Enterococcus species (8 cases, 14.03%). Salmonella paratyphi A was isolated in 2 cases (3.50%). Escherichia coli showed high susceptibility to aminoglycosides (18 cases, 100%), tigecycline (17 cases, 94.4%), and carbapenems (16 cases, 88.8%). Enterococci were highly susceptible to teicoplanin, tigecycline and linezolid. Follow-up was conducted post-discharge at 5 days, 15 days, and monthly thereafter. Conclusion: Gallstones act as a significant microenvironment for bacterial colonisation. Gallstone cultures, rather than bile cultures alone, provide a better understanding of gallstoneassociated microbiota, their role in disease pathogenesis, and postoperative complications. This information can help optimise antibiotic strategies, especially in high-risk or polymicrobial cases, leading to improved patient outcomes.