Impact of oral antibiotic prophylaxis on surgical site infection after rectal surgery: results of randomized trial.

AIM To evaluate the impact of oral antibiotic prophylaxis on surgical site infection (SSI) rate after rectal surgery. METHODS It was a single-center 1:1 randomized controlled open parallel trial (registration number NCT03436719). The patients undergoing rectal resection for benign and malignant tumors were assigned randomly to two groups: the oral plus intravenous (IV) antibiotic prophylaxis (AP) and the IV antibiotic prophylaxis only. The primary endpoint was the overall rate of SSI. RESULTS Between November 2017 and December 2018, 116 (male-55, the mean age-64 years) patients were enrolled into the trial. Of them, 57 had oral erythromycin 500 mg + metronidazole 500 mg a day before surgery and 1,000 mg of cephalosporin IV 30-90 min before operation. In the other group, 59 patients had the same IV antibiotics only. The incidence of SSIs was 22% (13/59) and 3.5% (2/57) correspondingly (р = 0.002). The statistically significant difference was detected for superficial SSI 0 (0%) vs. 5 (8.5%) (p = 0.03) and organ/space SSI 2 (3.5%) vs. 9 (15.3%) (p = 0.03), respectively. A multivariate analysis of risk factors of SSI identified two independent ones: bacterial contamination of the pelvic cavity ≥ 105 CFU at the end of surgery OR 17.9, 95% CI 2.1-150.0 (p = 0.008) and oral antimicrobial prophylaxis OR 0.2, 95% CI 0.03-0.8 (p = 0.02). CONCLUSION Oral-parenteral AP significantly reduced the risk of SSI following elective rectal surgery. Bacterial contamination of the pelvic cavity ≥ 105 CFU at the end of surgery and oral antimicrobial prophylaxis were independent risk factors of SSI.