M. avium complex (MAC) infection is the most common opportunistic mycobacterial infection in HIV-positive patients with CD4 counts below a threshold. At what CD4 cell count does NACO and WHO recommend MAC prophylaxis with azithromycin?

• A CD4 < 100 cells/µL
• B CD4 < 200 cells/µL
• C CD4 < 50 cells/µL ✓
• D CD4 < 350 cells/µL

Explanation

Both WHO and US CDC guidelines recommend MAC prophylaxis with weekly azithromycin (1200 mg) or daily clarithromycin when CD4 count falls below 50 cells/µL in HIV-positive patients not on ART or with inadequate immune reconstitution. MAC rarely causes disseminated disease at CD4 >100 cells/µL. PCP prophylaxis threshold is CD4 <200 cells/µL, and toxoplasmosis prophylaxis threshold is CD4 <100 cells/µL—these are distinct from MAC prophylaxis.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

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