Ileitis due to Yersinia pseudotuberculosis in Crohn's disease.

We present the case of a young woman with fulminating terminal ileitis due to Yersinia pseudotuberculosis, in whom Crohn's disease was subsequently diagnosed. Serological testing was prompted by radiological, macroscopic and histological changes which were atypical of Crohn's disease. We speculate that Y. pseudotuberculosis ileitis may occasionally produce an acute exacerbation of Crohn's disease, but that its occurrence may not be diagnosed if the atypical features are not recognised. In this case, the classical features of Y. pseudotuberculosis may have been modified by pre-existing Crohn's disease. We propose that, because of defects in mucosal barrier function and immunological function, patients with Crohn's may have increased susceptibility to infection by Yersinia sp.