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High prevalence of Escherichia coli belonging to the B2+D phylogenetic group in inflammatory bowel disease
  1. Roman Kotlowski1,
  2. Charles N Bernstein3,
  3. Shadi Sepehri2,
  4. Denis O Krause3
  1. 1Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada
  2. 2Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
  3. 3Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
  1. Correspondence to:
    Dr DO Krause
    Department of Animal Science, 236 Animal Science Building, University of Manitoba, Winnipeg, MB, Canada R3T 2N2; denis_krause{at}


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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