The combination of MBP+OAB versus MBP alone was associated with a significant reduction in SSI [risk ratio (RR) 0.51, 95% confidence interval (CI) 0.46–0.56, P < 0.00001, I2 = 13%], anastomotic leak (RR 0.62, 95% CI 0.55–0.70, P < 0.00001, I2 = 0%), 30-day mortality (RR 0.58, 95% CI 0.44–0.76, P < 0.0001, I2 = 0%), overall morbidity (RR 0.67, 95% CI 0.63–0.71, P < 0.00001, I2 = 0%), and development of ileus (RR 0.72, 95% CI 0.52–0.98, P = 0.04, I2 = 36%), with no difference in Clostridium difficile infection rates. The gene discussed is MBP; the disease is clostridium difficile infection.