The influence of oral versus parenteral preoperative metronidazole on sepsis following colon surgery.

The incidence of wound infection following surgery on the colon is reduced by the preoperative adminstration of appropriate antibiotics. Quantitative bacteriologic studies raise the fundamental question as to whether effective antibiotic prophylaxis results from reduction of the bacterial content of the gut prior to surgery or whether effective tissue levels of the antibiotic is the key factor. Oral neomycin and metronidazole have been shown to markedly reduce the incidence of wound infection following colon surgery. A prospective randomized double-blind clinical trial was undertaken to compare the effectiveness of intravenous metronidazole (high tissue level) with oral administration (tissue and gut activity) on the incidence of wound infection. There was no difference in wound infection rates between the two groups of patients. Surprisingly, there was a significant reduction in the bacteroides content in the colon of patients who received intravenous metronidazole one hour before operation to a level almost equal to that achieved by the administration of the drug for two days by mouth before operation. Metronidazole levels in the colon at the time of surgery were comparable for both groups. The median time for recolonization of the colon was six days for the oral group, and four days for the intravenous group. Although peritoneal fluid contained significant numbers of coliforms and enterococci, clinical infection did not occur. These data suggest that systemic antibiotics effective against anerobic flora of the colon markedly reduce postoperative septic complications.