Mechanical bowel preparation plus oral antibiotics reduces surgical site infection and anastomotic leak rates in elective colorectal cancer surgery: A systematic review and meta-analysis of randomised controlled trials.

BACKGROUND

Surgical site infection (SSI) and anastomotic leak (AL) are major contributors to postoperative morbidity in elective colorectal surgery. Although the addition of oral antibiotics (oAB) to mechanical bowel preparation (MBP) is recommended by several professional societies, uncertainty remains about its effectiveness and hence uptake globally is inconsistent, particularly in patients undergoing surgery for colorectal cancer (CRC).

METHODS

We conducted a systematic review and meta-analysis (PROSPERO CRD420251055720) of randomised controlled trials comparing MBP plus oAB with MBP alone in adult patients undergoing elective colorectal cancer resection. The primary outcomes were overall SSI. Secondary outcomes included CDC-defined SSI subtypes, AL and Clostridium difficile infection. A prespecified subgroup analysis was performed for trials limited to rectal cancer resections. Risk of bias was assessed using the RoB 2.0 tool, and the certainty of evidence was evaluated with GRADE methodology.

RESULTS

Nine trials comprising 3046 patients with colorectal cancer met inclusion criteria. Compared with MBP alone, the addition of oAB significantly reduced the risk of SSI (RR: 0.55, 95% CI: 0.44-0.68; I2 = 8%; p < 0.001) and AL (OR: 0.45, 95% CI: 0.32-0.65; I2 = 0%; p < 0.001). This benefit persisted across CDC-defined superficial incisional (RR: 0.53, 95% CI: 0.34-0.82; p = 0.005), deep incisional (RR: 0.40, 95% CI: 0.22-0.71; p = 0.002) and organ/space infections (RR: 0.55, 95% CI: 0.39-0.78; p < 0.001). In rectal cancer patients (n = 1172), the pooled risk of SSI remained lower with MBP plus oAB (RR: 0.48, 95% CI: 0.29-0.79; I2 = 41%; p = 0.004) and AL (OR: 0.40, 95% CI: 0.25-0.65; I2 = 0%; p < 0.001). Sensitivity analyses confirmed the robustness of these findings. The certainty of evidence was rated as moderate to high for all primary outcomes.

CONCLUSIONS

The addition of oral antibiotics to mechanical bowel preparation significantly reduces the risk of SSI and anastomotic leak in elective colorectal cancer surgery. The benefits are consistent in rectal cancer-specific cohorts, supporting the integration of oral antibiotics into standard bowel preparation protocols for patients undergoing colorectal cancer resection.