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.
Antibiotic prophylaxis in colorectal surgery. Combined doxycycline-tinidazole vs. doxycycline alone.
Single-dose doxycycline was compared with single-dose doxycycline + tinidazole in regard to prevention of septic complications after colorectal surgery, taking into account the type and level of surgery--right or left hemicolectomy, rectal operations and others. The study was performed as a prospective double-blind trial, with randomization in blocks. In colorectal surgery as a whole the combination was found to be more effective than doxycycline alone. When the four surgical blocks were separately considered, however, the difference between the two regimens was found to be mainly due to rectal operations, following which the incidence of abdominal and of perineal wound infections was significantly lower with the combined regimen than with doxycycline alone. The subgroups composed of right-sided or left-sided hemicolectomy or other operations were too small to permit definite conclusions.