Alteration of Intestinal Microflora Following Preoperative Mechanical Preparation of the Colon* RONALD L. NICHOLS, M.D.,t SHERWOOD L. GORBACH, M.D.* ROBERT E. CONDON, M.D.~ From the Departments of Surgery and Medicine, the Abraham Lincoln School of Medicine, University ol Illinois College o] Medicine, Chicago, Illinois PREOPERATIVE MECHANICAL CLEANSING Of the bowel with enemas and cathartics is associated with decreased morbidity and mortality in patients undergoing colonic op- erations. It is obvious that reducing the quantity of stool in the colon would lower the total number of microorganisms. How- ever, there is little information about the numbers or types of bacteria in the material remaining in the bowel after mechanical preparation. Knowledge of these microflora would be helpful in assessing potential wound contaminants and would provide a rational basis for selecting antimicrobials which might be added to the preoperative cleansing regimen. Below we report the results of quantita- tive cultures of stool and material obtained from the lumen of the intra-abdominal bowel. Findings in specimens from patients receiving vigorous preoperative mechanical bowel preparation were compared with those in specimens from control patients receiving no therapy. Material and Methods Patient Selection: Informed consent was obtained from 12 patients with chronic cal- culous cholecystitis admitted to the Univer- sity of lllinois Hospital for elective chole- cystectomy. They had not received anti- biotics, enemas, or cathartics for at least a month prior to admission to the hospital. *Received for publication August 13, 1970. t Instructor in Surgery. *Associate Professor of Medicine. w of Surgeryl Supported in part by grants from the National Aeronautics and Space Administration and the Na- tional Institute of Health (7-R22-AI-09851-01). 123 They were currently asymptomatic and had no past histories of intestinal disorders other than those related to chronic disease of the gallbladder. Patients were randomly assigned to two groups of six each. One group received a 72-hour mechanical preparation of the bowel, while the other group had no pre- operative preparation and served as the con- trols. A fast of approximately eight hours preceded every operation. The mechanical preparation used was: Day 1 1) Low-residue diet 2) Bisacodyl, 5 mg by mouth at 6:00 P.M. Day 2 1) Diet as on day 1 2) Magnesium sulfate, 30 ml of 50 per cent solution (15 g) by mouth at 10:00 A.M., 2:00 P.M., and 6:00 P.M. 3) Saline enemas in the evening un- til returns clear Day 3 1) Clear-liquid diet 2) Magnesium sulfate, 30 ml of 50 per cent solution (15 g) at 10:00 A.M. and 2:00 P.M. 3) No enemas Day 4 Operation at 8:00 A.M. Sample Collection: Stool specimens were obtained within 24 hours prior to operatioll in the control group and within four hours Dis. Col. & Rect. Volume 14 Mar:Apr. 1971 Number 2