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.
Cefoxitin for one day vs. ampicillin and metronidazole for three days in elective colorectal surgery. A prospective, randomized, multicenter study.
In a multicenter study the prophylactic efficacy of two antibiotic regimens was tested against postoperative septic complications following elective colorectal surgery. The study was conducted in a prospective block-randomized design. Patients were preoperatively allocated to either ampicillin, 1 gm, four times daily, and metronidazole, 0.5 gm, three times daily, for 72 hours, or to cefoxitin, 2 gm, given three times in a period of 10 hours. Both regimens were initiated immediately before surgery. Forty-five patients were withdrawn from the study after randomization. Three hundred fifty two patients (175 receiving ampicillin and metronidazole and 177 receiving cefoxitin) completed the study and were followed for one month postoperatively. The frequency of septic and nonseptic complications was not statistically significant different between the two regimens. About one third of all septic complications appeared more than two weeks after surgery. It is concluded that short-term treatment with cefoxitin is at least as efficient as a three-day treatment with ampicillin and metronidazole.