S4915 An Uncommon Ileitis: Mycobacterium mucogenicum Masquerading as Crohn's

Introduction: Mycobacterium mucogenicum is a rapidly growing non-tuberculous species associated with immune compromise and variable symptoms. Here we report a case of mucogenicum disease mimicking Crohn’s disease in an immune competent patient. Case Description/Methods: A 56-year-old man presented with 6 weeks of nonbloody diarrhea, subjective fever, fatigue, and 6-kilogram weight loss after traveling to Saudi Arabia. Initial stool tests were positive for Clostridium perfringens and azithromycin and then metronidazole brought brief improvement. Upon presentation to gastroenterology, testing included C-reactive protein 24 (ref <10 mg/L) and sedimentation rate 53 (ref <30 mm/hr). Quantiferron-Gold tuberculosis and stool testing (including Yersinia) were negative. Colonoscopy showed ileal erosions and biopsies demonstrated chronic ileitis. Magnetic resonance enterography showed hyperenhancement and wall thickening in the distal ileum. Acid-fast bacilli culture from the terminal ileum revealed M. mucogenicum. He received 14 days of moxifloxacin and diarrhea, fevers, and weight loss resolved. Subsequent colonoscopy revealed a normal terminal ileum with unremarkable histology and negative acid-fast bacilli culture. Discussion: This is a novel case of M. mucogenicum causing and ileitis that masqueraded as Crohn’s disease in an immune competent host. Characterized by chronic inflammation, Crohn’s has many mimics including infections, autoimmune, vascular, anatomic, and iatrogenic causes of inflammation. Among the infectious mimics, tuberculosis is well known. It shares symptoms such as pain, diarrhea, fever, and weight loss with Crohn’s and also causes ileitis. This patient presented with a symptomatic M. mucogenicum that created suspicion for Crohn’s disease. Mycobacterium mucogenicum is a rapidly growing non-tuberculous mycobacterium. It is frequently found in water supplies and sewage. Formation of M. mucogenicum biofilms contributes to persistence on surfaces and increases the potential for exposures. Catheter-associated infections are the most clinically significant. Skin ulcers and soft tissue abscesses, respiratory illness, and even central nervous system disease have described. This is a unique case of M. mucogenicum enteritis in an immune competent host. Its similarity to Crohn’s disease highlights the importance of a broad differential diagnosis.