Searching for the cause of IBD. Will MAPs help?▸

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Mycobacterium avium subspecies paratuberculosis (MAP) causes chronic enteritis in cattle (Johne’s disease). Cell wall deficient structures (spheroplasts) have been cultured from Crohn’s disease tissues, and have been confirmed by DNA hybridisation techniques as MAP. MAP is extremely difficult to culture, and studies have used the DNA insertion element IS900 for identification. Polymerase chain reaction cannot distinguish viable MAP from MAP DNA. Studies to date have been conflicting and the role of MAP remains controversial. Naser and colleagues, from Orlando, Florida, USA have previously cultured MAP from tissue and breast milk of Crohn’s patients, but not controls.

In the present study (n = 52), buffy coat preparations of peripheral blood were tested for MAP by polymerase chain reaction and culture. MAP DNA was detected in 46% of Crohn’s, 44% of ulcerative colitis, and 20% of controls. MAP was isolated from culture in 50% of Crohn’s, 22% of ulcerative colitis, and no controls (a highly significant difference). Sixteen of 28 Crohn’s patients were on immunosuppression but this did not correlate with positive cultures.

These results provide further evidence that MAP is common in the environment, and that patients with Crohn’s disease have systemic …