[Crohnie]

NEW YORK (Reuters Health) Aug 21 -- A selective increase in a novel type of invasive Escherichia coli relative to depletion of Clostridial species appears to be involved in the etiology of Crohn's disease, according to a report in the July 12th issue of the ISME Journal: Multidisciplinary Journal of Microbial Ecology.

In the study, Dr. Kenneth W. Simpson, from Cornell University in Ithaca, New York, and colleagues used DNA analysis to compare the ileal microbial flora of patients with ileum-involved or colon-only Crohn's disease and of healthy subjects.

Compared with the other groups, the ileum-involved Crohn's group showed an increase in E. coli species and decrease in Clostridiales. Moreover, the severity of the ileitis was directly related to the number of E. coli present. Lastly, only invasive species of E. coli were found in inflamed mucosa.

Further analysis showed that the invasive E. coli exhibited novel phylogeny with characteristics similar to that of extraintestinal pathogenic E. coli and Enterobacteriaceae.

"Our findings raise the possibility that a novel group of E. coli contains opportunistic pathogens that may be causally related to chronic intestinal inflammation in susceptible individuals," Dr. Simpson said in a statement. "They suggest that an integrated approach that considers an individual's mucosa-associated flora in addition to disease phenotype and genotype may improve outcome."