Microbiological etiology and current resistance patterns in acute calculous cholecystitis

The current treatment for acute calculous cholecystitis (ACC) is early laparoscopic cholecystectomy, in association with appropriate empiric antibiotic therapy. In our country, the evolution of the prevalence of the germs involved and their resistance patterns have been scarcely described. The aim of the study was to analyze the bacterial etiology and the antibiotic resistance patterns in ACC.

We conducted a single-center, retrospective, observational study of consecutive patients diagnosed with ACC between 01/2012 and 09/2019. Patients with a concomitant diagnosis of pancreatitis, cholangitis, postoperative cholecystitis, histology of chronic cholecystitis or carcinoma were excluded. Demographic, clinical, therapeutic and microbiological variables were collected, including preoperative blood cultures, bile and peritoneal fluid cultures.

A total of 1104 ACC were identified, and samples were taken from 830 patients: bile in 89%, peritoneal fluid and/or blood cultures in 25%. Half of the bile cultures and less than one-third of the blood and/or peritoneum samples were positive. Escherichia coli (36%), Enterococcus spp (25%), Klebsiella spp (21%), Streptococcus spp (17%), Enterobacter spp (14%) and Citrobacter spp (7%) were isolated. Anaerobes were identified in 7% of patients and Candida spp in 1%. Nearly 37% of patients received inadequate empirical antibiotic therapy. Resistance patterns were scrutinized for each bacterial species. The main causes of inappropriateness were extended-spectrum beta-lactamase-producing bacteria (34%) and Enterococcus spp (45%), especially in patients older than 80 years.

Updated knowledge of microbiology and resistance patterns in our setting is essential to readjust empirical antibiotic therapy and ACC treatment protocols.