ASSOCIATION BETWEEN INTRAEPITHELIAL ESCHERICHIA-COLI AND COLORECTAL-CANCER

Background & Aims: Although multiple studies have focused on Helicobac ter pylori, little is known about the mucosa-associated flora of the c olon. The aim of this study was to detect bacteria directly in colonic mucosa from patients screened for colorectal cancer. Methods: Bacteri a were quantified with the polymerase chain reaction and identified by comparative sequence analysis in colonoscopic biopsy specimens from 3 1 asymptomatic and 34 symptomatic controls with normal colonoscopic fi ndings, 29 patients with colonic adenoma, and 31 patients with colorec tal carcinoma. In 41 patients, intra- and extracellular location of ba cteria was confirmed with the gentamicin protection assay. Results: No bacteria were detected in biopsy specimens from 97% of asymptomatic a nd 69% of symptomatic controls. In contrast, bacterial concentrations of 10(3)-10(5) colony-forming units per microliter were detected in bi opsy specimens from both malignant and macroscopically normal tissue i n 90% and 93% of patients with adenoma and carcinoma, respectively. E. coil and coil-like bacteria were shown to colonize the colonic mucosa in 82% of these patients. The gentamicin protection assay indicated t hat E. coli was partially intracellular in 87% of patients with adenom a and carcinoma and in none of the controls. Conclusions: The colonic mucosa of patients with colorectal carcinoma but not normal colonic mu cosa is colonized by intracellular E. coil.