High prevalence of Mycobacterium avium subspecies paratuberculosis IS900 DNA in gut tissues from individuals with Crohn's disease

Abstract

Background and aims: Conflicting results exist about the presence of Mycobacterium avium subspecies paratuberculosis (MAP) specific IS900 DNA in Crohn's disease (CD) tissues. Therefore, we examined IS900 in a large number of gut samples from patients with CD (n = 100) and ulcerative colitis (UC, n = 100), and in non-inflamed control tissues (nIBD, n = 100). We hypothesised that IS900 DNA detection might be associated with distinct clinical phenotypic characteristics in CD.

Methods: The prevalence of MAP DNA in surgically resected tissues was examined using a mechanical-enzymatic disruption technique and nested IS900 specific polymerase chain reaction (PCR). CD patients were stratified according to the criteria of the Vienna classification and other clinical characteristics.

Results: IS900 PCR detection rate was significantly higher in CD tissue samples (52%) than in UC (2%) or nIBD (5%) specimens (p<0.0001). In CD patients, IS900 DNA was detected in samples from both diseased small bowel (47%) as well as from the colon (61%). No firm association between MAP specific IS900 detection rates and clinical phenotypic characteristics in CD could be established. However, corticosteroid medication constituted a factor which tended to have a negative influence on IS900 DNA detection rates in CD (p<0.01).

Conclusions: The presence of MAP specific IS900 DNA is a predominant feature of CD. Therapeutic intervention against MAP might represent a potential target for disease mitigation in Crohn's disease.

Figure 1

Agarose gel electrophoresis of polymerase chain reaction (PCR) products obtained from transmural bowel specimens following IS900 [L/AV] nested PCR (Crohn’s disease cases, two samples tested per case). Site of tissue sampling indicated as (C) colon, (R) rectum, and (IL) ileum. Lanes 1C, 2C, 3C, 4R, 5C, 6R, 7IL, 10IL, positive samples (+) with a specific amplification product of 298 bp. Lanes 8IL, 9IL, 11IL, 12IL, negative samples (−). Note variation in band intensity of the amplified products on the gels. Regarding lanes 5C and 10IL, both samples were positive. Positive controls consisted of a plasmid (pIDL60) containing a single copy of IS900. Inhibition controls consisted of pIDL60 “spiked” into each sample after processing.