Mycobacterium avium Complex: An Emerging Pathogen in IBD and Non-IBD Diarrhea: Preliminary Results

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Introduction: The pathogenesis of inflammatory bowel disease (IBD) has been postulated to be multifactorial: including immune dysregulation, gut bacteria, genetic predisposition, and infection. One possible infectious pathogen is Mycobacterium avium complex (MAI). MAI causes intestinal disease in other animal species with histological changes similar to Crohn’s disease (CD). MAI is ubiquitous, having been found in retail milk and in domestic water supplies. MAI can be evasive microscopically, but with the application of PCR and stool cultures, there has been an increase in the diagnosis of MAI. To date, there have been few clinical trials looking at the significance of MAI in the stool. We examine the clinical implication of MAI in the stool of patients with diarrhea and/or colitis, with or without IBD. Methods: We conducted a prospective study on patients who are undergoing a colonoscopy either for diagnosis of diarrhea or colitis or a known history of IBD. During colonoscopy, stool was collected through the colonoscope and sent for culture, ova and parasites, C. difficle, Wright stain, viral culture, along with AFB stain and culture. Informed consent was obtained for each patient enrolled in the trial. Results: Thirty-three patients were recruited for the study; 16 had IBD (10 with ulcerative colitis, 6 with Crohn’s disease) and 17 non-IBD patients had diarrhea. Fifty percent (8/16) of IBD patients had MAI in the stool. Sixty-five percent (11/17) of the non-IBD patients with diarrhea had MAI in their stool. To date, 1 patient each in the IBD group and diarrhea group are undergoing treatment with anti-mycobacterial therapy and show significant clinical improvement. The remainder patients are being evaluated for treatment. Conclusion: This study suggests that MAI may be an emerging pathogen in patients with both IBD and non-IBD related diarrhea. Our data shows that MAI should be considered not only in immunocompromised patients but also in immunocompetent hosts. A recent case reported disseminated pulmonary MAI in a patient with CD who had received one dose of Infliximab. Screening for tuberculosis and viral hepatitis exposure is standard of care in IBD patients prior to biologic therapy. It may also be prudent to screen for MAI in IBD patients prior to starting immunosuppression (i.e. biologics, anti-TNF therapy), in order to avoid the potential of disseminated MAI. MAI should be also be considered in the non-IBD patient with diarrhea or colitis. Thus, we believe that stool should be evaluated for MAI (with an AFB stain and culture) in the workup of all patients who present with diarrhea and/or colitis. Further studies evaluating the potential role of MAI in IBD and non-IBD patients with diarrhea may be warranted.

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