Rare Case of Mycobacterium Avium Complex Peritonitis in a Patient with Multiple Myeloma Undergoing Peritoneal Dialysis.

Mycobacterium avium complex (MAC) infections can present as a variety of severe diseases. While it has a predilection for immunocompromised patients such as those with Human immunodeficiency virus (HIV), it can also affect immunocompetent patients as well. One of the rare yet severe diseases that MAC infections can present is MAC peritonitis. Often hard to distinguish from other causes of peritonitis, high clinical suspicion should be maintained for those who are susceptible. Here we present an 85-year-old female with a past medical history of end-stage renal disease on peritoneal dialysis who presented with nausea and vomiting. She was found to have tenderness around her peritoneal dialysis site and was noted to have mild ascites. Her labs were significant for several electrolyte abnormalities, leukocytosis, and ascitic fluid obtained during a previous admission, and serology was positive for acid-fast bacilli. It was further revealed that the species was Mycobacterium avium complex. Initially, she started on rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE), subsequently antibiotics were changed to azithromycin, ethambutol, and rifampin after MAC identification in acid-fast bacilli culture. We aim to highlight this rare presentation of peritonitis secondary to MAC.