Mycobacteria and inflammatory bowel disease. Results of culture

We have been able to isolate mycobacteria from intestinal specimens obtained by surgical resection or endoscopic biopsy from patients with Crohn's disease, ulcerative colitis, and noninflammatory bowel diseases. Nineteen slow-growing (Runyon groups I and III) and 17 rapid-growing (Runyon group IV) mycobacterial isolates were obtained. Slow-growing mycobacteria were recovered from approximately one-third of intestinal biopsy specimens from Crohn's disease, one-quarter of ulcerative colitis biopsies, and 40% of biopsies from noninflammatory bowel disease patients. Isolates were most commonly members of the Mycobacterium avium-complex. One isolate (from an ulcerative colitis patient) was biochemically similar to the Mycobacterium strain previously associated with Crohn's disease, and one from a Crohn's disease patient was Mycobacterium kansasii. The rapid-growing organisms were members of the Mycobacterium fortuitum-complex. In addition to conventional mycobacteria, spheroplasts (cell wall-defective forms) were isolated from 12 patients with Crohn's disease (most often from surgically resected colon) and 3 patients with ulcerative colitis; none were isolated from non-inflammatory bowel disease patients. We have been unable to identify a consistent relationship between the presence, or the species, of Mycobacterium and Crohn's disease. Our results do not support the proposed role of a specific mycobacterium in the pathogenesis of Crohn's disease. The cause of Crohn's disease remains unclear.