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ABSTRACT

JOURNAL OF CLINICAL MICROBIOLOGY, 0095-1137/00/$04.0010
Dec. 2000, p. 4373-4381 Vol. 38, No. 12

Results of Multiple Diagnostic Tests for Mycobacterium avium subsp. paratuberculosis in Patients with Inflammatory Bowel Disease and in Controls

Michael T. Collins,1* Gorm Lisby,2 Claus Moser,3 Debra Chicks,4 Steen Christensen,5 Mark Reichelderfer,4 Niels HøIby,3 Bruce A. Harms,6 Ole Ø. Thomsen,5 Ulrik Skibsted,2 And Vibeke Binder5
Department of Pathobiological Sciences, School of Veterinary Medicine,1 and Department of Clinical Gastroenterology and Department of Medicine4 and Department of Surgery,6 Medical School, University of Wisconsin, Madison, Wisconsin, and Department of Clinical Microbiology, Rigshospitalet,3 and Department of Clinical Microbiology2 and Department of Medical Gastroenterology,5 Herlev Hospital, Copenhagen, Denmark

Received 17 July 2000/Returned for modification 9 August 2000/Accepted 26 September 2000

Mycobacterium avium subsp. paratuberculosis has been incriminated as a cause of Crohn's disease (CD); however, studies to date have been relatively small and generally only used a single diagnostic assay. The objective of the study was to reexamine the association of M. avium subsp. paratuberculosis and CD using multiple diagnostic tests. Five methods were used to detect M. avium subsp. paratuberculosis infections in 439 inflammatory bowel disease (IBD) patients and 324 control subjects in the United States and Denmark. Most assays were adaptations of diagnostic tests for this infection performed routinely on animals. PCR for IS900, a genetic element unique to M. avium subsp. paratuberculosis, was positive significantly more often on resected bowel and lymph node tissues from CD patients (19.0%) and ulcerative colitis (UC) patients (26.2%) than from controls (6.3%) (P < 0.05). Positive IS900 PCR results occurred more often in U.S. than in Danish IBD patients, 32.0 versus 13.3% (P = 0.025). The majority of Danish patients were bacillus Calmette-Guérin (Mycobacterium bovis BCG) vaccinated (CD, 77.5%; UC, 86.6%; controls, 83.0%) whereas none of the U.S. patients with IBD and only 2% of U.S. controls were vaccinated. Among Danish IBD patients, positive PCR findings were four times more common among subjects who were not BCG vaccinated (33.3%) than among BCG vaccinates (8.8%, P = 0.02). Culture of the same tissues tested by PCR using modified BACTEC 12B medium failed to grow M. avium subsp. paratuberculosis from patients or controls. U.S. CD patients had the highest serological evidence (enzyme-linked immunosorbent assay [ELISA] for serum antibodies) of M. avium subsp. paratuberculosis infection (20.7% of patients positive) which was higher than for all UC patients studied (6.1%) or healthy controls (3.8%, P < 0.005). Among Danish patients alone, however, no significant differences in rates of ELISA-positive results among CD, UC, or control patients were found. For 181 study subjects, both IS900 PCR and ELISA were performed. Although 11 were ELISA positive and 36 were PCR positive, in no instance was a patient positive by both tests, suggesting that these states are mutually exclusive. Evaluation of cytokine-mediated immune responses of IBD patients was complicated by the influence of immunosuppressive therapy given most IBD patients. Gamma interferon (IFN-gamma) release by peripheral blood leukocytes after M. avium purified protein derivative PPD antigen stimulation showed significantly lower responses in CD patients than in UC patients or controls in both U.S. (by ex vivo assay) and Danish (by in vitro assay) populations (P < 0.05). Interleukin-5 responses were not different among CD, UC, or control groups. Collectively, the PCR, ELISA, and IFN-gamma tests for M. avium subsp. paratuberculosis together with the unexpected observation that BCG vaccination influenced M. avium subsp. paratuberculosis detection, lead us to conclude that M. avium subsp. paratuberculosis, or some similarly fastidious mycobacterial species, infects at least a subset of IBD patients. Whether the infection is primary (causal) or secondary, it may contribute to the etiopathogenesis of IBD.


PARA's SUMMARY

THE MOST CONSERVATIVE CONCLUSION OF THIS STUDY IS THAT THERE IS AN ASSOCIATION BETWEEN MAP AND CROHN'S DISEASE. WHILE NOT CONCLUDING THAT MAP CAUSES CROHNS, BY USING A VARIETY OF DIFFERENT TESTS, IT DRAWS AN INDELIBLE LINK: WHERE THERE IS MAP, THERE IS LIKELY TO BE CROHN'S. WHERE THERE IS CROHN'S, THERE IS LIKELY TO BE MAP.


Source: http://www.crohns.org/articles/2000_12_4373-81_jcm.htm   Contact PARA: http://www.crohns.org/contact.htm
Paratuberculosis Awareness & Research Association