Analysis of Escherichia coli isolated from patients affected by Crohn's disease.

The etiopathogenesis of Crohn’s disease (CD) is still controversial: several genetic, immunologic, and environmental factors, including some bacteria, have been implicated. This study has been devised to assess the involvement of Escherichia coli in CD. Seven E. coli strains were isolated from 14 biopsies obtained from ileal and colic ulcers of patients affected by inflammatory bowel disease (IBD), including 6 with ulcerative colitis and 8 with CD. Five strains, exclusively isolated from CD patients, were found inside mucosal cells. Different PCR techniques (for chuA, yjaA, TspE4.C2, escV and bfpB genes) were performed and PFGE was carried out to characterize these bacteria in comparison with other E. coli strains isolated from non-IBD specimens. The correlation of these characters with bacterial invasiveness on intestinal (Caco-2) and phagocytic (U937) cells was assessed. Overall our pilot data suggest that 5 among 8 strains isolated from CD patients belonged to the adherent-invasive E. coli (AIEC) group, characterized by the gene chuA (present in B2 and D E. coli phylogenetic groups), and were invasive on Caco-2 cells and resistant to phagocytosis. Therefore these findings suggest that these bacteria could be considered target organisms whose elimination could reduce the intestinal inflammatory process and CD progression.