Antibiotic prophylaxis in large bowel surgery: results of a controlled clinical trial.

A prospective, randomized clinical trial was undertaken to compare the value of a combination of two antibiotics for the prevention of postoperative septic complications after large bowel surgery. In group I the patients received three doses daily for 2 days of 80 mg gentamicin and 600 mg clindamycin, intravenously. Patients in group II received three doses daily for 2 days of 80 mg gentamicin and 500 mg metronidazole. Antibiotic administration was started in the operating room before the surgical procedure. The two antibiotics were administered by separate venous routes. One hundred and seven patients were allocated to either one of the two groups. Both groups were equally matched for gender, age, and surgical procedure. Bacteriologic specimens were taken in the wound as soon as the peritoneum was closed. They were immediately incubated for identification by aerobic and anaerobic cultures and sensitivity determinations. Cultures of one or more organisms were positive in 63 of 107 specimens. There was no difference between the two groups. No death occurred as a result of intra-abdominal complication, no reoperation was required, and in no case did peritonitis occur. Six wound abscesses and three delayed stitch infections were observed: five in group I and two in group II. Five clinical anastomotic leakages were observed (5.1%): two in group I and three in group II. They did not require treatment and healed spontaneously. Furthermore, five radiologic anastomotic leakages were present in 45 patients who received a control barium enema. No side effects were noted with metronidazole of with clindamycin. No clinical evidence of ototoxicity or nephrotoxicity was observed in patients receiving gentamicin. There is no statistically significant clinical difference between the combination of gentamicin and metronidazole or gentamicin and clindamycin. Both combinations are effective in preventing wound sepsis in large bowel surgery. Metronidazole and clindamycin were equally effective in preventing postoperative anaerobic infections. No resistance of anaerobic organisms to metronidazole was observed.