METRONIDAZOLE MAY INHIBIT INTESTINAL COLONIZATION WITH CLOSTLIDIUM DIFFICILE

PURPOSE: Antibiotics suppress normal gut flora, allowing overgrowth of acquired or native Clostridium difficile, with release of toxins that cause mucosal inflammation. Oral metronidazole is used to treat antib iotic-associated colitis (pseudomembranous colitis). This study was de signed to determine whether oral metronidazole, as part of preoperativ e bowel preparation, prevents or decreases incidence of antibiotic-ass ociated colitis after elective colonic and rectal procedures. METHODS: Eighty-two patients (40 men) were prospectively, randomly assigned to receive one of two oral antibiotic regimens before colorectal surgery . Ail patients underwent mechanical bowel preparation with polyethylen e glycol-electrolyte lavage solution before administration of oral ant ibiotics. Group 1 (n = 42) patients received three doses (1 g/dose) of neomycin and erythromycin. Group 2 (n = 40) patients received three d oses (1 g/dose) of neomycin and metronidazole. Both groups received on e preoperative and three postoperative doses of intravenous cefotetan (2 g/dose). Both groups had stool samples tested for C. difficile toxi n in the preoperative and postoperative periods by enzyme-linked immun oabsorbent assay or by tissue culture cytotoxicity. Patients with preo perative stool studies positive for C. difficile were excluded from th e study. RESULTS: Treatment groups were not different for age, gender, or surgical procedure. Mean age +/- 1 standard deviation was 67.6 +/- 13.6 (range, 34-34) years in Group 1 and 62.1 +/- 13.5 (range, 35-84) years in Group 2 (P = 0.069). Mean length of hospital stay +/- 1 stan dard deviation was 9.76 +/- 4.9 (range, 4-28) days for Group 1 and 8.0 5 +/- 2.6 (range, 3-14) days for Group 2 (P = 0.053). Five patients in Group 1 (neomycin and erythromycin) and one patient in Group 2 (neomy cin and metronidazole) had positive stool studies for C. difficile. Re lative risk of colonization with C. difficile in Group 1 was 4.76 time s that in Group 2 (95 percent confidence interval, 0.581, 33). This di fference was not statistically significant (P = 0.202). There were no significant differences in C. difficile colonization rates with respec t to age, length of stay, or gender. CONCLUSIONS: This study suggests that there may be a clinical association between use of metronidazole preoperatively and inhibition of intestinal colonization by C. diffici le in this patient population undergoing colonic and rectal surgery.