Background: It is not clear which species of bacteria may be involved in inflammatory bowel disease (IBD). One way of determining which bacteria might be likely candidates is to use culture-independent methods to identify microorganisms that are present in diseased tissues but not in controls.
Aims: (1) To assess the diversity of microbial communities of biopsy tissue using culture-independent methods; (2) to culture the bacteria found in the tissues of patients with IBD but not in the controls; (3) to identify potential virulence factors associated with cultured bacteria.
Methods: 84 biopsy specimens were collected from 15 controls, 13 patients with Crohn’s disease (CD) and 19 patients with ulcerative colitis (UC) from a population-based case–control study. Ribosomal intergenic spacer analysis (RISA) was conducted to identify unique DNA bands in tissues from patients with CD and UC that did not appear in controls.
Results: RISA followed by DNA sequencing identified unique bands in biopsy specimens from patients with IBD that were classified as Escherichia coli. Targeted culture showed a significantly (p<0.05) higher number of Enterobacteriaceae in specimens from patients with IBD. The B2+D phylogenetic group, serine protease autotransporters (SPATE) and adherence factors were more likely to be associated with tissues from patients with UC and CD than with controls.
Conclusions: The abundance of Enterobacteriaceae is 3–4 logs higher in tissues of patients with IBD and the B2+D phylogenetic groups are more prevalent in patients with UC and CD. The B2+D phylogenetic groups are associated with SPATE and adherence factors and may have a significant role in disease aetiology.
- CD, Crohn’s disease
- IBD, inflammatory bowel disease
- PAI, pathogenicity island
- RFLP, restriction fragment length polymorphism
- RISA, ribosomal intergenic spacer analysis
- SPATE, serine protease autotransporters
- UC, ulcerative colitis
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Published Online First 6 October 2006
Funding: This work was funded by the Crohn’s and Colitis Foundation of Canada. CNB is supported in part by a Crohn’s and Colitis Foundation of Canada Research Scientist Award.
Competing interests: None.
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