Presence of adherent Escherichia coli strains in ileal mucosa of patients with Crohn's disease

Background & Aims: Infectious agents are suspected of being involved in the pathogenesis of Crohn's disease, This study was designed to look for the p resence of virulent Escherichia coil strains associated with the ileal muco sa of patients with Crohn's disease. Methods: E. coli strains were recovere d from resected chronic ileal lesions (n = 20), neoterminal ileum after sur gery from patients with (n = 19) and without (n = 11) endoscopic recurrence , and controls (n = 13), Bacterial adhesion was determined in vitro using i ntestinal cell lines; other associated virulence factors were assessed by D NA hybridization and polymerase chain reaction experiments, Results: None o f the strains harbored any of the virulence factor-encoding genes of E. col i involved in acute enteric diseases, However, mannose-resistant adhesion t o differentiated Caco-2 cells was found for 84.6% and 78.9% of the E. coil strains isolated from chronic and early recurrent lesions, respectively, co mpared with 33% of controls (P < 0.02), In addition, 21.8% of the strains i nduced a cytolytic effect by synthesis of an alpha-hemolysin. Conclusions: E. coil strains isolated from the ileal mucosa of patients with Crohn's dis ease adhere to differentiated intestinal cells and may disrupt the intestin al barrier by synthesizing an alpha-hemolysin.