A Case of Silent Mycobacterial Endocarditis Masked as Refractory Hyperparathyroidism

Non-tuberculous mycobacteria are a rare cause of infectious endocarditis and are associated with a high mortality rate. Formal recommendations guiding treatment are lacking, non-standardized, and generally rely on prior case reports. This report adds to the current literature with the intent to help guide management in similar patients. A 70-year-old female with a history of chronic, primary hyperparathyroidism and recent mitral valve replacement with an ultra-porcine bioprosthesis nine months prior presented for altered mental status secondary to hypercalcemia (total calcium: 12.5 mg/dL, free calcium: 1.84 mg/dL). Through her hospital course, it was determined she had <i>Mycobacteria fortuitum</i> endocarditis of the prosthetic mitral valve complicated by septic emboli to the brain. Antibiotics were initiated, and she was clinically stable at the time of report submission. This case highlights the need for antimicrobial susceptibility to guide management. Furthermore, many of the antibiotics utilized are known to cause serious adverse effects, decreasing their tolerability, and an important factor to consider. Complications due to non-tuberculous mycobacterial endocarditis itself can be devastating and may contribute to the high mortality rate as well.