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.
A multicenter randomized trial of prophylaxis with intravenous cefepime + metronidazole or ceftriaxone + metronidazole in colorectal surgery. The 230 Study Group.
We compared two prophylactic antimicrobial regimens in 615 patients undergoing elective colorectal surgical procedures. Patients ranged in age from 19 to 92 years (median 66 years); the majority were male (54.0%) and most (77.7%) had neoplastic disease. All underwent mechanical bowel preparation. Patients were randomized to receive preoperative infusions of 2 g cefepime (n=307) or 2 g ceftriaxone (n=308), followed by 500 mg metronidazole. Patients were followed for up to 4 to 6 weeks after surgery. Antimicrobial prophylaxis was successful in preventing primary site infections in 92.8% of patients in the cefepime + metronidazole arm and 92.9% of patients in the ceftriaxone + metronidazole arm. Both regimens were well tolerated. A single dose of cefepime + metronidazole thus seems to be a very useful alternative to other regimens for prophylaxis in patients undergoing colorectal surgery.