Antibiotics covering aerobic and aerobic bacteria should be delivered orally and intravenously prior to colorectal surgery.  Antibiotics delivered within this framework will reduce the risk of postoperative SWI by at least 75%.  Further research is required to establish the optimal timing and duration of dosing, and frequency of longer-term adverse effects such as Clostridium difficile pseudomembranous colitis.
Systemic Timentin is superior to oral tinidazole for antibiotic prophylaxis in elective colorectal surgery. University of Melbourne Colorectal Group.
A prospective, randomized, single-blind, controlled clinical trial was undertaken to compare two different prophylactic antibiotic regimens in patients undergoing elective colorectal surgery. Systemic Timentin, a combination of ticarcillin and the beta-lactamase inhibitor clavulanic acid, was assigned to 101 patients. Oral tinidazole, an agent active only against anaerobic bacteria, was assigned to 102 patients. The wound infection rate was 2.4 percent in the patients receiving Timentin and 14 percent in those receiving tinidazole (P = 0.01). Multivariate analysis of factors affecting the wound infection rate showed that the only factor that independently reached statistical significance was the prophylactic antibiotic used. The mortality of patients receiving Timentin prophylaxis was 3.4 percent compared with 8.9 percent of those receiving tinidazole (P = 0.15). The clinical anastomotic leakage rate was 1.3 percent in patients receiving Timentin and 13 percent in those receiving tinidazole (P = 0.01). These results, together with those of two previously published clinical trials by this group, indicate that antibiotic prophylaxis in elective colorectal surgery should consist of a short course of an agent effective against both aerobic and anaerobic bowel flora.