Incidence of Mycobacterium avium subspecies paratuberculosis in a population-based cohort of patients with Crohn's disease and control subjects.
OBJECTIVE
To define the incidence of Mycobacterium avium subspecies paratuberculosis (MAP) in patients with Crohn's disease (CD) and in control subjects.


METHODS
Blood samples from 361 CD patients from a previously described population-based inflammatory bowel disease (IBD) cohort and 200 blood donor controls, of known NOD2 genotype, were screened by PCR for MAP-specific IS900 DNA. These results were correlated with NOD2 genotype.


RESULTS
The PCR assay was capable of detecting 20 fg of purified MAP DNA, equivalent to roughly 100 MAP cells/mL of blood. MAP-specific IS900 DNA was detected in 33.8% of CD cases and 21.5% of controls (OR 1.86, 95% CI 1.247-2.785, P= 0.002). All study participants were genotyped for the NOD2 mutations 2104C>T (R702W), 2722G>C (G908R), and 3020insC (1007fs). Carriage of one or two NOD2 mutations was not associated with a significantly higher risk of CD (OR 0.75, 95% CI 0.465-1.207, P= 0.234). No significant association was seen in the CD cohort for carriage of one or two NOD2 mutations and MAP status (OR 0.883, 95% CI 0.494-1.579, P= 0.675).


CONCLUSIONS
Screening peripheral blood using IS900 PCR indicated that MAP DNA could be detected in a significant proportion of CD cases from a large population-based cohort, and also, in control subjects. The over-representation of MAP DNA in CD suggests either a role or a probable role for MAP in the etiology of CD.
Bentley
Robert W
RW
Department of Pathology, University of Otago, Christchurch, New Zealand.
Keenan
Jacqui I
JI
Gearry
Richard B
RB
Kennedy
Martin A
MA
Barclay
Murray L
ML
Roberts
Rebecca L
RL
D015331:Cohort Studies; D003424:Crohn Disease / Q000453:epidemiology* / Q000235:genetics; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D016927:Mycobacterium avium subsp. paratuberculosis / Q000235:genetics; D009520:New Zealand; D053473:Nod2 Signaling Adaptor Protein; D010283:Paratuberculosis / Q000453:epidemiology*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity
D004269:DNA, Bacterial; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein