Suggested use of empirical antibiotics in acute cholecystitis based on bile microbiology and antibiotic susceptibility

Background: Bacterial infection is common in acute cholecystitis (AC). To identify appropriate empirical antibiotics, we investigated AC-associated microorganisms and their susceptibilities to antibiotics. We also compared preoperative clinical findings of patients grouped according to specific microorganisms. Methods: Patients who underwent laparoscopic cholecystectomy for AC between 2018 and 2019 were enrolled. Bile cultures and antibiotic susceptibility tests were performed, and clinical findings of patients were noted. Results: A total of 282 patients were enrolled (147 culture-positive and 135 culture-negative). The most frequent microorganisms were Escherichia (n = 53, 32.7%), Enterococcus (n = 37, 22.8%), Klebsiella (n = 28, 17.3%), and Enterobacter (n = 18, 11.1%). For Gram-negative microorganisms, second -generation cephalosporin (cefotetan: 96.2%) was more effective than third-generation cephalosporin (cefotaxime: 69.8%). Vancomycin and teicoplanin (83.8%) were the most effective antibiotics for Enterococcus. Patients with Enterococcus had higher rates of CBD stones (51.4%, p = 0.001) and biliary drainage (81.1%, p = 0.002), as well as higher levels of liver enzymes, than patients with other micro-organisms. Patients with ESBL-producing bacteria had higher rates of CBD stones (36.0% vs. 6.8%, p = 0.001) and biliary drainage (64.0% vs. 32.4%, p = 0.005) than those without. Discussion: Preoperative clinical findings of AC are related to microorganisms in bile samples. Periodic antibiotic susceptibility tests should be conducted to select appropriate empirical antibiotics.