S3402 Enterocolitis Caused by Mycobacterium Avium Complex in an HIV-Infected Patient

Abstract

Introduction: Diarrhea in patients with human immunodeficiency virus (HIV) can be due to a variety of etiologies including infection, malignancy, and antiretroviral therapy (ART). With increased use of ART, diarrhea due to opportunistic infections has become less common. Here we report a rare case of chronic diarrhea due to Mycobacterium avium complex (MAC) infection involving the duodenum, colon, and rectum of a patient with advanced HIV. Case Description/Methods: A 41-year-old man with HIV infection diagnosed two years earlier presented with progressively worsening diarrhea. Two months prior, his CD4 count was stable at 50 cells/uL and his HIV level was undetectable while on dolutegravir/lamuvidine. He had history of MAC mycobacteremia under treatment with ethambutol, azithromycin, and rifabutin. He also had cytomegalovirus (CMV) viremia treated with valganciclovir. He reported compliance with the above medications. He had eight-month history of frequent, watery diarrhea associated with malaise, nausea, bloating, abdominal pain, and weight loss. He was hospitalized for severe malnutrition and electrolyte abnormalities. Evaluation of his diarrhea included negative C. difficile toxin, enteric pathogen panel, and ova and parasite exam. CMV was detected in the blood at 17,000 IU/mL and HIV viral load was 6,166 IU/mL. Esophagogastroduodenoscopy was performed and revealed diffuse erythema and edema affecting the mucosa of the entire duodenum with associated villous blunting and fissuring (Figure A). Flexible sigmoidoscopy revealed normal appearing mucosa to the level of the ascending colon. Pathology from duodenal biopsies showed extensive histiocytic inflammation with presence of acid-fast bacillus organisms (Figures B and C). Random biopsies from the colon and rectum showed similar findings and no evidence of CMV. Acid-fast bacillus blood cultures grew Mycobacterium avium-intracellulare. His MAC treatment was changed to amikacin, linezolid, rifampin, and ethambutol with subsequent improvement in his diarrhea. Discussion: Gastrointestinal tract involvement by MAC is usually part of a disseminated MAC infection in patients with advanced HIV, especially those with CD4 lymphocyte counts < 50 cells/uL. The duodenum is most often affected, followed by the rectum. We report this case to raise awareness that MAC enterocolitis remains an important etiology of chronic diarrhea in patients with advanced HIV.Figure 1.: A, EGD showing duodenal involvement by MAC causing diffuse erythema and edema with villous blunting and fissuring. B, H&E stain of duodenal mucosa with extensive histiocytic inflammation. C, Ziehl-Neelsen stain of duodenal mucosa with acid-fast bacillus positive organisms consistent with Mycobacterium avium complex.