Abstract
BackgroundAssociation of Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn’s disease (CD) has been controversial due to contradictory reports. Therefore, we determined the prevalence of MAP in patients with CD and intestinal tuberculosis (ITB) and its association with clinical course.MethodologyBlood and intestinal biopsies were taken from 69 CD, 32 ITB patients and 41 patients with haemorrhoidal bleed who served as controls. qPCR targeting of MAP-specific IS900 gene was used to detect the presence of MAP DNA. qPCR results were further validated by sequencing. Immunohistochemistry (IHC) was used to detect the presence of MAP antigen in biopsy specimens. CD and ITB patients were followed-up for disease course and response to therapy.Principal FindingsThe frequency of MAP-specific DNA in biopsies by qPCR was significantly higher in CD patients (23.2%, p = 0.03) as compared to controls (7.3%). No significant difference in intestinal MAP presence was observed between ITB patients (12.5%, p = 0.6) and controls (7.3%). MAP presence in blood of CD patients was 10.1% as compared to 4.9% in controls while no patients with ITB were found to be positive (p = 0.1). Using IHC for detection of MAP antigen, the prevalence of MAP in CD was 2.9%, 12.5% in ITB patients and 2.4% in controls. However, long-term follow-up of the patients revealed no significant associations between clinical characteristics and treatment outcomes with MAP positivity.ConclusionWe report significantly high prevalence of MAP in intestinal biopsies of CD patients. However, the presence of MAP does not affect the disease course and treatment outcomes in either CD or ITB patients.
Highlights
The aetiology of Crohn’s disease (CD) is unknown and believed to be complex and multifactorial, wherein genetic and environmental factors play a significant role
The CD group consisted of 69 patients (45 males and 24 females), intestinal tuberculosis (ITB) group consisted of 32 patients (20 males and 12 females) and healthy controls consisted of 41 controls (29 males and 12 females)
The frequency of Mycobacterium avium subspecies paratuberculosis (MAP)-specific IS900 DNA in biopsy samples by qPCR was significantly higher in CD patients (23.2%, p = 0.03) as compared to the controls (7.3%)
Summary
The aetiology of Crohn’s disease (CD) is unknown and believed to be complex and multifactorial, wherein genetic and environmental factors play a significant role. Several studies have reported contrasting observations regarding the association of MAP and CD in humans [9,10,11,12,13,14]. India has been an endemic area for intestinal tuberculosis (ITB) in humans as well as JD in ruminants. The existence of CD, ITB, and JD in India formed a strong basis to study the prevalence MAP in CD and ITB patients. In the present study, we have evaluated the prevalence of MAP in CD and ITB patients using TaqMan based qPCR assays as well as immunohistochemistry (IHC) of tissue biopsies. Association of Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn’s disease (CD) has been controversial due to contradictory reports. We determined the prevalence of MAP in patients with CD and intestinal tuberculosis (ITB) and its association with clinical course
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