Clinical trial of prophylaxis of wound sepsis in elective colorectal surgery: Cephamandole with tinidazole versus tinidazole alone

A prospective randomized double-blind clinical trial was undertaken to determine whether prophylactic therapy with an antibiotic agent active against anaerobic bacteria needs to be supplemented by an antibiotic agent predominantly active against aerobic bacteria to minimize postoperative wound sepsis caused by enteric organisms in elective colorectal surgery. Two hundred and eleven patients were studied, of whom 100 received tinidazole and cephamandole, and 111 received tinidazole and a placebo. Wound infection occurred in 7% of the tinidazole/cephamandole group and in 9% of the tinidazole/placebo group (P > 0.7). After patients who required a second laparotomy, and those with staphylococcal wound infections were excluded, the wound infection rate in patients who received prophylaxis with combination chemotherapy was 2% compared with 9% in patients who received tinidazole alone (P = 0.03, Fisher's exact test). When patients with intra-abdominal sepsis were also excluded, the wound infection rate in the tinidazole group fell to 7%; in the combination therapy group, it remained at 2% (P = 0.08). There was a significant reduction in the mean wound infection rate in the combination chemotherapy group (P = 0.05, Fisher's exact test) when patients of the two surgeons who contributed two-thirds of the patients in the trial were excluded from analysis.