Aerobic Intraoperative Abdominal Cavity Culture Modifies Antibiotic Therapy and Reduces the Risk of Surgical Site Infection in Complicated Appendicitis with Peritonitis

Introduction: Appendectomy is one of the most performed surgeries and is the leading cause of acute abdomen.[1] The usefulness of intraoperative cultures in complicated appendicitis is controversial.[2] The current evidence presents important methodological limitations and studies are needed to evaluate outcomes in patients with intraoperative cultures. We analyzed the impact of intraoperative aerobic culture on the modification of antibiotic therapy and the clinical evolution of patients with complicated appendicitis.

Methods: Retrospective cohort study of 144 adults with complicated appendicitis (localized or generalized peritonitis) in a high complexity hospital in Colombia from 2014 to 2022. The intraoperative sample was taken according to the attending surgeon’s decision. The procedure of how the cultures were taken and analyzed can be found in the supplementary material. The primary outcomes included the modification of antibiotic therapy, surgical site infection (SSI) during the first 30 postoperative days, reintervention, length of hospital stay, and mortality. All patients were evaluated in a postsurgical outpatient visit. A Cox proportional hazards model was used with the subsequent reporting of the hazard ratio. The project was approved by the Health Ethics Committee.

Results: Intraoperative culture was collected in 42.4% (n=61) patients, 56.2% had a laparoscopic approach. In most cases, the chosen empiric antibiotic as well as the therapy duration was guided according to the hospital protocol (Table 1); 86.9% of the patients had a positive culture result. The most isolated microorganisms were Escherichia coli and Pseudomonas aeruginosa (Fig. 1). E. coli resistance to beta-lactams was detected in 38.5% (n=17) of the cultures. Four of them were positive for extended-spectrum beta-lactamase (ESBL), and 13 presented inhibitor-resistant TEM. Three of the 13 isolates of P. aeruginosa were found to be resistant to beta-lactams, one of them was resistant to carbapenems