Region-specific protection effect of preoperative oral antibiotics combined with mechanical bowel preparation before laparoscopic colorectal resection: a prospective randomized controlled trial

Background: Oral antibiotics (OA) combined with mechanical bowel preparation (MBP) significantly decrease the rate of surgical site infections (SSIs). However, the prophylactic effects in region-specific colorectal surgery have not been assessed.Materials and methods: A single-centre, single-blind, randomized controlled trial was conducted from 2019 to 2022. Patients were eligible if they were diagnosed with nonmetastatic colorectal malignancy, and laparoscopic colorectal surgery was indicated. Participants were randomly assigned (1:1) to the experimental (OA+MBP preparation) or control group (MBP preparation). The randomization was further stratified by resected region. The primary outcome was the incidence of SSIs. Patients were followed up for 1 month postoperatively, and all complications were recorded.Result: Between 2019 and 2022, 157 and 152 patients were assigned to the experimental and control groups, respectively, after 51 patients were excluded. The incidence of SSIs in the control group (27/152) was significantly higher than that in the experimental group (13/157; P=0.013), as was the incidence of superficial SSIs (5/157 vs. 14/152, P=0.027) and deep SSIs (7/157 vs. 16/152, P=0.042). After redistribution according to the resected region, the incidence of SSIs was significantly higher in the control group with left-sided colorectal resection (descending, sigmoid colon, and rectum) (9/115 vs. 20/111, P=0.022) but was similar between the groups with right-sided colon resection (ascending colon) (3/37 vs. 7/36, P=0.286). No differences were noted between the groups in terms of other perioperative complications.Conclusion: OA+MBP before colorectal surgery significantly reduced the incidence of SSIs. Such a prophylactic effect was particularly significant for left-sided resection. This preparation mode should be routinely adopted before elective left-region colorectal surgeries.