QUANTITATIVE CULTURES OF THE MUCOSAL-ASSOCIATED BACTERIA IN THE MECHANICALLY PREPARED COLON AND RECTUM

Little is known about the mucosal microflora of the colon and rectum a t the time of elective surgery. Our objective was to determine the con centrations of anaerobic and aerobic bacteria associated with the muco sa of the mechanically prepared large bowel. Ten patients were studied after a standard polyethylene glycol-electrolyte lavage preparation. No patient had taken antibiotics in the preceding four weeks. Sterile wire brushes passed through the colonoscope during advancement were us ed to culture the rectal, transverse colon, and cecal mucosa. Total an aerobic, aerobic, Gram-positive, and enteric bacterial counts were det ermined along with specific cultures for Bacteroides fragilis, Clostri dium difficile, Escherichia coli, Pseudomonas aeruginosa, enterococcus , and staphylococcus species. The results showed that there was a sign ificant increase (P < 0.01) in aerobes, anaerobes, enterics, Gram posi tives, B. fragilis, and E. coli mucosal counts with proximal progressi on. Aerobes showed a steady gradient, while anaerobes demonstrated an increase from the rectum to the transverse colon but no change between the transverse colon and cecum. We conclude that, in the prepared bow el, there is an increase in the mucosal bacterial counts in the more p roximal portions of the bowel. The results may serve as a baseline for future studies on the mucosal-associated bacteria of the large intest ine.