Post-operative Infections After Emergent Laparotomy for Traumatic Perforated Viscera: An Assessment of Risk Factors and Antimicrobial Prophylaxis.

Introduction Trauma involving perforated viscera is at high risk for surgical site infection (SSI). Standard practice is to give peri-operative prophylactic antibiotics within one hour before surgery. There is still uncertainty regarding the best specific agents and how trauma-related variables interact with prophylactic antibiotics. Methods This retrospective cohort study assessed patients undergoing exploratory laparotomy due to traumatic hollow visceral perforation between 1/1/2020 and 12/31/2023. The primary objective was to assess risk factors for post-operative infections. Other outcomes were death, hospital and ventilator days, and intensive care unit treatment. Significance testing for categorical and continuous data was performed with the chi-squared test and t-test, respectively. Multivariate analysis for binary and continuous outcomes was performed with logistic and linear regression, respectively. Results Two hundred thirty-one patients were included. SSI occurred in 26 (11%) with superficial, deep, and organ space infections documented in six, six, and 14 patients, respectively. Ertapenem was the most common antimicrobial prophylaxis (168, 73%). Antimicrobial prophylaxis without expected activity against anaerobes was given in 46 patients (20%). No antimicrobial prophylaxis was administered in 10 patients (4%). Antimicrobials were administered within 60 minutes prior to the procedure in 150 patients (65%). Patients who received peri-operative antibiotic prophylaxis with any agent had six SSIs (2.9%) versus four SSIs (15.4%) for patients who received no antibiotic prophylaxis of any kind (p=0.017). Patients who received ertapenem prophylaxis had one trauma-related SSI (0.6%) versus four SSIs (6.2%) for patients who received antibiotic prophylaxis with any other agent (p=0.008). On multivariate analysis, the adjusted odds ratio for infection associated with ertapenem prophylaxis versus any other agent was protective at 0.05 (p=0.01). Hospital length of stay (LOS) was 20.3 days for patients who received post-operative antibiotics versus 12.1 days for those who did not receive post-operative antibiotics (p<0.01). Patients who received massive transfusion protocol (MTP) had eight SSIs (22.2%) versus 17 SSIs (8.8%) for those who did not receive MTP (p=0.02). Patients who received post-operative vasopressors had nine SSIs (22%) versus 17 SSIs (9%) for those who did not receive post-operative vasopressors (p=0.02). Patients whose abdominal fascia was left open at the end of the index operation had 21 SSIs (16.4%) versus five SSIs (4.9%) for those whose fascia was closed immediately (p=0.01).  Conclusion Lack of antibiotic prophylaxis, MTP, post-operative vasopressors, and open abdomen predict SSI. Ertapenem was associated with a lower traumatic wound infection rate, but not SSI. Other specific antibiotic agents and timing intervals were not significant. Variables that are surrogates for trauma severity are more accurate predictors of SSI than specific antibiotic agents and timing.