Which medication is used for prophylaxis against Mycobacterium avium complex (MAC) in patients with a CD4 count less than 50?

Azithromycin is the medication used for prophylaxis against Mycobacterium avium complex (MAC) in patients with a CD4 count of less than 50 cells/µL. In such immunocompromised individuals, specifically those with advanced HIV/AIDS, the risk of opportunistic infections increases significantly, and MAC is one of the key infections to watch for. Standard prophylaxis with azithromycin is prescribed to decrease the risk of developing this infection, especially since MAC commonly occurs in patients with severely compromised immune systems.

While other options might be relevant for different indications, they do not serve the purpose of MAC prophylaxis. Ceftriaxone is a broad-spectrum cephalosporin antibiotic effective against various bacteria but does not cover atypical mycobacterial infections like MAC. Emtricitabine is an antiretroviral medication used primarily in the treatment of HIV, not for MAC prophylaxis. Trimethoprim/Sulfamethoxazole is effective for many bacterial infections and is typically used for prophylaxis against Pneumocystis jirovecii pneumonia (PCP) rather than MAC. Thus, the choice of azithromycin is particularly important for preventing MAC specifically among patients with very low CD4 counts.