The BACILO study was designed with the objective of having robust data on local epidemiological bacterial colonisation information on bile cultures with patients taken to laparoscopic cholecystectomy in our institution to find which predictive factors are associated with culture positivity and antibiotic resistance patterns. Secondary endpoints include evaluating demographical, clinical and surgical variables and establishing comparison between both positive and negative bile cultures and between antibiotic sensitive and resistant microorganism strain isolations.

BACILO is single-centre, observational, analytical, prospective study with a prognostic prediction model with the objective of identifying predictive factors associated with microbial and antibiotic resistance patterns in bile cultures of patients taken to laparoscopic cholecystectomy in our institution. Primary outcomes are bile culture positivity and phenotypical resistance antibiogram patterns while secondary outcomes include demographic, clinical and surgical characteristics and surgical outcomes. The main objective is to determine predictive factors using a prediction model, variables included are: Age, diabetes mellitus, C-reactive protein test, choledocholithiasis/ERCP, cholecystitis and severity of cholecystitis according to the 2018 Tokyo guidelines.This in the nature of describing the relationship between bile culture positivity and phenotypical antibiogram resistance patterns in our institution, and establish thus better treatment strategies based on higher quality local evidence.

Inclusion Criteria:

• Patients included must be over 18 years of age and be taken to laparoscopic cholecystectomy between March 2024 and February 2026 in any institution of the Méderi hospital network (Hospital Universitario Mayor and Hospital Universitario Barrios Unidos), have signed the written informed consent to be included in the study and have both bile culture and antibiogram.

Exclusion Criteria:

• - Patients that will be taken to laparoscopic cholecystectomy with another concomitant surgical procedure (including but not exclusive to gastrectomy, pancreatoduodenectomy, oesophagectomy, splenectomy, abdominal wall reconstruction, colectomy, amongst others) with the exception of umbilical herniorrhaphy.
• Patients without a postoperative control appointment.
• Patients with an untreated HIV diagnosis.
• Patients with diagnosis of a malignant gallbladder or biliary tract disease documented preoperatively.

Patients that are over 18 years that have an indication for laparoscopic cholecystectomy in our institution without any of the exclusion criteria, which had bile cultures taken from the surgical specimen (gallbladder) during the surgery and attended the postoperative15 day follow-up appointment after hospital discharge.

Data obtained and input into the database is anonymous, without any individual or identifying characteristics will be stored in a dataset from the Centro de Recursos para el Aprendizaje y la Investigación, property of and administered by the Universidad del Rosario as a plan of data management. Moreover, the different codes used in the analysis will be stored in this dataset.

It is in our plans once we obtain a register number from Clinical Trials in order to publish the protocol, statistical analysis plan and clinical study report in a scientific journal so it will be available to all people interested.

It is in our plans to be published in a scientific journal available to all people interested.