Targeted Versus Standard Peri-operative Antibiotic Prophylaxis in Patients Colonized With Carbapenemase Producing Enterobacterales Undergoing Liver Transplantation

This is a multicenter stepped-wedge cluster randomized trial, conducted over a 2-year period at three hospitals. The trial is structured into four phases, each lasting six months. During phase 1 (pre-rollout), all hospitals will use standard antibiotic prophylaxis for all patients. In each of phases 2 to 4, one hospital will switch to targeted antibiotic prophylaxis, so that by phase 4 all hospitals will be using it. The order in which hospitals switch is determined by computer-generated randomization performed centrally by an independent statistician, ensuring each hospital has an equal chance of switching at any given phase and minimizing selection bias. The goal of this clinical trial is to learn whether targeted antibiotic prophylaxis works better than standard antibiotic prophylaxis at preventing infections in liver transplant patients who carry resistant bacteria called CPE (carbapenemase-producing Enterobacterales). It will also learn about the effects of these antibiotics on gut bacteria. The main questions it aims to answer are: * Does targeted antibiotic prophylaxis reduce the number of CPE infections occurring in the first two weeks after liver transplant, compared to standard prophylaxis? * How do targeted and standard antibiotic prophylaxis affect the gut microbiome after transplant? * Is there a link between achieving optimal antibiotic blood levels and the risk of developing an infection after transplant? Researchers will compare targeted antibiotic prophylaxis (chosen based on the specific bacteria each patient carries) to standard antibiotic prophylaxis (used routinely at each hospital) to see which approach better prevents infection. This study does not involve the administration of any drugs or instrumental examinations beyond those already part of standard clinical care at each center. However, additional blood tests will be performed by collecting one extra blood sample (and a bile sample, if the patient has a Kehr's tube, which is a drain placed in the bile duct after surgery) during blood draws already scheduled as part of routine clinical practice, in order to measure drug levels in the blood. Stool samples will also be collected specifically for the study to investigate the gut microbiome.