Mycobacteria as a possible cause of inflammatory bowel disease.

Mesenteric lymph-nodes from 27 patients with Crohn's disease, 13 with ulcerative colitis, and 11 without inflammatory bowel disease were cultured for mycobacteria. A node from a patient with Crohn's disease yielded a strain of Mycobacterium kansasii. Cultures from 22 other patients with Crohn's disease, 7 with ulcerative colitis, and 1 control subject yielded pleomorphic organisms with the electron-microscopic appearances of cell-wall-deficient organisms. Further culture and characterisation of these organisms has so far proved unsuccesful. Skin tests with tuberculin were positive in a smaller proportion of patients with Crohn's disease than in healthy control subjects. Conversely, the patients gave a higher proportion of positive reactions to a reagent prepared from the strain of M. kansasii isolated. No differences in the proportion of positive test were found between patients and controls with reagents prepared from 16 other mycobacteria. Cell-wall-deficient mycobacteria are a possible causative agent of inflammatory bowel disease.