Background: In an immunohistochemical study a higher rate of reactivity of intestinal tissues to the antibody against Listeria monocytogenes was reported in Crohn's disease as compared with controls.

Methods: Seventy-six intestinal tissues, either therapeutically resected or biopsied, from 31 patients with Crohn's disease, 20 with ulcerative colitis, and 21 with non-inflammatory bowel disease were studied. DNA extracted from intestinal tissues by proteinase K treatment was used for nested polymerase chain reaction (PCR), using two sets of primers. PCR products were analyzed with agarose gel electrophoresis and subsequent Southern blot analysis.

Results: Our amplification system could detect 9 pg of L. monocytogenes DNA. L. monocytogenes was detected in only one sample, that from a patient with ulcerative colitis.

Conclusions: Our study does not support the etiologic significance of L. monocytogenes in Crohn's disease.