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.
[Duration of the preventive use of antibiotics in colorectal surgery--single administration versus short-term prevention].
The effect of a combination of 4 g mezlocillin and 0.5 g metronidazole for the prophylaxis against infections in a one-shot dose immediately preoperatively compared to a short-time dose of 2 days given to 90 patients with resection of colorectal carcinoma was investigated in a prospective and randomized study. 6 patients developed a wound infection in the early postoperative phase; 4 of these infections (3 were severe, 1 was mild) occurred in the one-shot group and 2 in the short-time prophylaxis group. After more than 20 days postoperatively 3 late infections were observed which had a mild course (2 cases in the one-shot group, 1 case in the short-time prophylaxis group). All infections were localized in the sacral wound region in patients with abdominoperineal resection. The abdominal wounds healed per primam in each case. Besides those, 26 infections of the urinary tract were observed, which occurred significantly more often after the one-shot dose (40.9%) than with the short-time prophylaxis (18.6%). Intraoperative smears of the lumen of the bowels showed a remaining bacterial settlement. Besides Bacteroides species, especially Escherichia coli were found among the isolates. Moreover in some cases Clostridium, Klebsiella, Proteus and Pseudomonas could be identified. Smears of the site of operation (sacral/peritoneal cavity) were contaminated in over 50%, above all by Bacteroides species; besides those, E. coli were found most often. The subcutaneous smears showed a growth of the germs only in a few cases. Aerobic bacteria in 93.8%, anaerobic bacteria except for thetaiotaomicron and B. asaccharolyticus in 85.1%.(ABSTRACT TRUNCATED AT 250 WORDS)