Reducing Surgical Site Infection in Colorectal Surgery Using Mechanical Bowel Preparation and Oral Antibiotics: a Comparative Study in the Era of Enhanced Recovery After Surgery (ERAS) Protocol

Surgical site infection in colorectal surgery is prevalent compared to other surgeries due to colonic bacterial load. This has serious implication on recovery, length of stay, readmission, mortality and duration to oncological treatment. We hypothesized that mechanical bowel preparation and oral antibiotics (MBP + OA) reduces surgical site infection in patients undergoing colorectal resection. Our institution introduced MBP + OA for elective colorectal surgeries in 2020. Inclusion criteria were as follows: (1) open colorectal resection, (2) low rectal resection with defunctioning ileostomy and (3) resection of locally advanced colorectal tumour requiring laparoscopically assisted approach. All patients who met these criteria were enrolled. Characteristics and outcomes were compared with control population from previous year that met the criteria but did not receive MBP + OA. 148 patients were studied between January 2019 and June 2021. 68 received MBP + OA; 80 did not. The MBP + OA group had a lower surgical site infection rate of 8.8% vs. 25.0% in the control group (p = 0.018). Multivariate analysis revealed that MBP + OA is an independent protective factor for surgical site infection (odds ratio = 0.30, confidence interval 0.106-0.851; p = 0.024) while open approach is an independent predictor for surgical site infection (odds ratio = 7.435, confidence interval 1.863-29.666; p = 0.004). There was no difference in anastomotic leak rate (p = 0.45). With regards to ERAS-specific outcomes, the MBP + OA group had higher rate of establishing solid diet by POD2 (57.4% vs. 33.8%, p = 0.0067) and shorter day to bowel opening (1.88SD1.08 vs. 2.39SD1.79). MBP + OA is effective in reducing surgical site infection and complements ERAS. This is one of the first studies to be conducted in the Asian population.