Prevalence of Adherent-Invasive Escherichia coli with fimH Gene Isolated from Iranian Patients with Ulcerative Colitis

Ulcerative colitis is a kind of inflammatory bowel disease that is considered as immunological response to commensal bacteria colonizing gut lumen. Adherent-invasive Escherichia coli strains are pathogens responsible for ulcerative colitis disease. These bacteria have special virulence factors, including type 1 fimbriae, which could be involved in inflammatory bowel disease.
The present study was conducted to determine the prevalence of adherent-invasive E. coli with fimH gene isolated from Iranian patients with ulcerative colitis.
Sixty intestinal biopsy samples of 30 patients with ulcerative colitis and 30 individuals without inflammatory bowel disease were examined. Biopsies from rectum, descending, ascending, terminal ileum, and colon were taken during colonoscopy.
All biopsy samples were cultured for isolation of E. coli strains. Using polymerase chain reaction assay, the invasive plasmid antigen H and invasion-association locus genes were detected from both isolated bacteria and tissue specimens to confirm the presence of adherent-invasive E. coli. The frequency of adherent-invasive E. coli with type 1 fimbriae was much higher in patients with ulcerative colitis than control subjects. Among isolated bacteria, type 1 fimbriae of adherent-invasive E. coli were detected in 53.3% and 13.3% of ulcerative colitis patients and control subjects, respectively. In addition, from 60 biopsy samples, type 1 fimbriae were detected in 56.7% of ulcerative colitis patients but in 10% of healthy subjects.
Subjects without inflammatory bowel disease had a high rate of E. coli strains than patients with ulcerative colitis via cultivation detection. We found a high rate of type 1 fimbriae of adherent-invasive E. coli in ulcerative colitis patients by polymerase chain reaction assay. It appears that the presence of adherent-invasive E. coli with type 1 fimbriae in the gastrointestinal tract of patients with ulcerative colitis is more likely than previously supposed.