Single or multiple doses of metronidazole and ampicillin in elective colorectal surgery. A randomized trial.

A randomized trial including 294 patients was performed to evaluate the prophylactic effect of single vs. multiple doses of antibiotics in elective colorectal surgery. All patients received 1.5 g metronidazole and 3.0 g ampicillin peroperatively and were randomized to: no further prophylactic antibiotic treatment, or ampicillin 1 g X 3 and metronidazole 0.5 g X 3 given intravenously during the second and third postoperative days. Deep wound infection was seen in 9/149 (6 percent) receiving a single dose and in 8/145 (6 percent) receiving multiple doses. No differences were found in the two groups between frequencies of anastomotic dehiscences, intra-abdominal abscesses, sepsis, and pulmonary infections. The two groups were similar according to distribution of sex, age, diagnosis, and type of surgery. A single peroperative dose of metronidazole and ampicillin is a simple and satisfactory antibiotic prophylaxis in elective colorectal surgery.