Dominant genotypes in mucosa-associated Escherichia coli strains from pediatric patients with inflammatory bowel disease

BACKGROUND: Studies performed in adults with inflammatory bowel disease (IBD) have suggested that mucosa-associated Escherichia coli strains may be involved in its pathogenesis. The aim of this study was to characterize E. coli strains from the intestinal mucosa of pediatric IBD patients to investigate whether a particular subset of strains could be associated with the disease. METHODS: We analyzed the genomic and phenotypic traits of 60 E. coli strains isolated from biopsies of pediatric patients with Crohn's disease (CD), ulcerative colitis (UC), and from age-matched controls. RESULTS: No noteworthy differences were found in the distribution of phylogroups. The percentage of adhesive E. coli strains was similar in biopsies from patients and controls. However, the adhesion ability of E. coli strains differed between ileal and colonic or rectal areas, only in the strains from CD and UC patients. The percentage of E. coli possessing more than 1 of the adhesive/virulence determinants was significantly higher in strains from UC than from CD and controls. Interestingly, the genetic profile examination revealed 2 large clusters of genetically linked E. coli strains from IBD patients. Ninety-two percent of the strains isolated from CD patients were in the first cluster (A) and were distributed between 2 genetic subclusters (A1 and A2), while a second cluster (B) contained most of the strains isolated from UC (78%; subcluster B1), and control strains (77%; subcluster B2). CONCLUSIONS: Genomic analysis of mucosa-associated E. coli strains found a close genetic association between strains isolated from CD and UC patients.