Detection of Mycobacterium avium subspecies paratuberculosis in surgicalpathology blocks from patients with Crohn's disease in China

AIM To determine whether MAP can be detected in archival paraffin embedded full thickness samples ofintestinal tissue from patients in China with Crohn's disease (CD), ulcerative colitis (UC), and in controlsubjects (NIBD) having surgery for bowel cancer.METHODS Optimized procedures for the removal of paraffin, recovery of tissue and access to MAP DNA,followed by MAP-specific nested IS900 PCR. Confirmation of specific amplification by Southern blotting andDNA sequencing.RESULTS IS900 PCR positive tests identified MAP in 9 (69%) of 13 CD, 1 of 3 UC and 2 (14%) of 14NIBD in the presence of correctly reporting positive and negative sample and reagent control reactions. DNAsequence analysis of the 298bp IS900 PCR amplification product from MAP in 2 Chinese CD patientsdemonstrated 99% homology with the GenBank IS900 sequence accession number X16293.CONCLUSION Although larger numbers of Chinese samples need to be studied, these initial results areconsistent with an exposure of human populations in China to MAP, and an involvement of this pathogen inchronic inflammation of the intestine of the Crohn's disease type. The results are in agreement with similarpositive studies reported from China, from Western Europe and elsewhere.