Which Mycobacterium is most noted for being associated with patients with AIDS?

• A. M. avium complex
• B. M. marinum
• C. M. kansasii
• D. M. bovis

Answer: (A)

In advanced AIDS, opportunistic infections with non-tuberculous Mycobacteria are a major concern, and the Mycobacterium avium complex stands out as the classic example. MAC commonly causes disseminated disease in patients with very low CD4 counts, leading to fever, night sweats, weight loss, anemia, hepatosplenomegaly, and gastrointestinal symptoms. This widespread involvement reflects the organism’s ability to survive and multiply inside macrophages when the immune system is severely compromised, making MAC the most notable AIDS-associated mycobacterial infection.

In contrast, M. marinum tends to cause localized skin and soft tissue infections after aquatic exposure; M. kansasii usually presents as pulmonary disease resembling TB, typically in people with underlying lung disease; and M. bovis is classically linked to tuberculosis-like disease from unpasteurized dairy products, not specifically tied to AIDS.