Preoperative antibiotics for mild or moderate acute cholecystitis (POMMAC): study protocol for a non-inferiority, open-label, randomized controlled trial

Background: Evidence is lacking on the effect of preoperative antibiotic therapy on postoperative infections in acute cholecystitis. The POMMAC trial aims to investigate whether a single dose of antibiotic prophylaxis is non-inferior to continuous preoperative antibiotic therapy in terms of postoperative infections. Methods: This is a non-inferior, open-label randomized controlled trial aiming to include 456 participants. Eligible participants with mild or moderate acute cholecystitis will be randomized at a 1:1 ratio to receive either continuous or a single dose of preoperative antibiotic prophylaxis. The primary outcome is the rate of postoperative infections within 30 days postoperatively. Secondary outcomes are rates of conversion from laparoscopic to open cholecystectomy, other postoperative complications (Clavien-Dindo), a composite outcome incorporating antibiotic-related hypersensitivity reactions, Clostridium difficile diarrhea, and yeast infections within 30 days postoperatively, and the length of stay. Discussion: The POMMAC trial will provide evidence on the effect of preoperative antibiotic therapy on postoperative infections in acute cholecystitis. Abstaining from unnecessary preoperative antibiotic therapy could reduce antimicrobial resistance, adverse antibiotic-related events, and healthcare expenses. Trial registration: EU CTIS: https://euclinicaltrials.eu/search-for-clinical-trials/?lang=en&EUCT=2024-515958-24-00 protocol version 2.4. Registered on April 9th, 2025.