MYCOBACTERIUM-PARATUBERCULOSIS DNA NOT DETECTED IN CROHNS-DISEASE TISSUE BY FLUORESCENT POLYMERASE CHAIN-REACTION

The role of mycobacteria in the aetiology of Crohn's disease has been a contentious subject for many years. Mycobacterium paratuberculosis i s known to cause a chronic granulomatous enteritis in animals (Johne's disease) and has been implicated as a possible infectious cause of Cr ohn's disease. However this fastidious organism is only rarely detecte d by conventional microbiological techniques. This study used oligonuc leotide primers to the species-specific M paratuberculosis IS900 DNA i nsertion element and the polymerase chain reaction to amplify any M pa ratuberculosis DNA from intestinal tissue DNA extracts. One oligonucle otide primer was fluorochrome-labelled and the presence of fluorescent amplified product was determined using an automated DNA sequencer wit h a computerised gel-scanning laser. This method was shown capable of detecting 1-2 mycobacterial genomes. Intestinal tissue samples were ob tained from 68 patients with histologically confirmed Crohn's disease, 49 patients with histologically confirmed ulcerative colitis, and 26 non-inflammatory bowel disease controls. In no case was M paratubercul osis detected in any of the inflammatory bowel disease tissue samples and only one non-inflammatory bowel disease case was positive. These r esults do not support the hypothesis that M paratuberculosis has an ae tiological role in Crohn's disease.