Presence of eubacteria in biopsies from Crohn's disease inflammatory lesions as determined by 16S rRNA gene-based PCR.

The aim of this study was to search for putative microbial agents in Crohn's disease (CD) tissues by bacterial broad-range 16S rDNA PCR combined with genus- and species-specific DNA hybridisation analysis. Biopsies taken both surgically and endoscopically from the terminal ileum of 11 CD patients and 11 control patients were investigated. Significant amounts of eubacteria were demonstrated in biopsies taken endoscopically from both affected and unaffected individuals; the biopsies taken at surgery from control patients were negative. Three of five biopsies taken surgically from CD patients harboured Helicobacter spp.-, Mycobacterium paratuberculosis-, Listeria monocytogenes- and Escherichia coli-like 16S rDNA sequences. These findings show the importance of the sampling method chosen when combined with molecular typing of eubacteria in intestinal tissues. The mixed bacterial flora found in the surgical biopsies from CD patients supports the idea that the enteric microflora enters primary lesions where secondary bacterial colonisers may elicit a chronic inflammatory syndrome.