A 28-year-old man recently diagnosed with HIV has a CD4 count of 180 cells/µL. He is about to start ART. At what CD4 threshold should prophylaxis for Pneumocystis jirovecii pneumonia (PJP) be started, and what is the preferred agent?
- A CD4 < 200 cells/µL; co-trimoxazole (TMP-SMX) double strength daily ✓
- B CD4 < 350 cells/µL; dapsone
- C CD4 < 100 cells/µL; pentamidine inhaled monthly
- D CD4 < 50 cells/µL; atovaquone
Correct answer: A. CD4 < 200 cells/µL; co-trimoxazole (TMP-SMX) double strength daily
Explanation
PJP primary prophylaxis is indicated when CD4 < 200 cells/µL (or CD4% < 14%), as the risk of PJP increases steeply below this threshold. Co-trimoxazole (TMP-SMX, DS, one tablet daily) is the drug of choice due to efficacy, cost, and additional protection against Toxoplasma gondii encephalitis. Dapsone, atovaquone, and pentamidine are alternatives for sulfonamide-intolerant patients. The CD4 < 100 threshold is relevant for Toxoplasma prophylaxis (also TMP-SMX). Prophylaxis can be stopped when CD4 > 200 for ≥ 3 months on effective ART.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.