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.
[Parenteral antibiotic prophylaxis or oral antimicrobial bowel preparation for colorectal surgery (author's transl)].
A prospective randomized trial was designed to establish whether parenteral antibiotic prophylaxis was as effective as oral antimicrobial bowel preparation in preventing sepsis after colorectal surgery. Patients scheduled for elective resection of colorectal cancer received metronidazole and kanamycin either orally in the preoperative phase or parenterally as a short-term perioperative prophylaxis. The former regimen resulted in reduction of the microbial concentrations in the bowel contents in the absence of therapeutic serum concentrations at the time of operation, whereas the latter achieved therapeutic intraoperative serum levels without altering the colonic microflora. 72 patients were studied. There was no significant difference in the occurrence of postoperative sepsis between the two groups (a total of 72 patients). These results differ from those obtained at the Birmingham General Hospital using the same protocol, in which postoperative sepsis was significantly more common in the group of patients having oral bowel preparation. This difference was most probably due to an overgrowth of kanamycin-resistant coliforms during the period of oral antibiotic preparation. The presence of resistant organisms did not, however, result in failure of systemic prophylaxis. The authors conclude that short-term parenteral application is the safer method of antibiotic prophylaxis in colorectal surgery and is to be preferred to oral antimicrobial bowel preparation.