A 32-year-old HIV-positive man (CD4 count 45 cells/µL) develops fever, dry cough, and exertional dyspnea. CXR shows bilateral diffuse interstitial infiltrates. LDH is 680 U/L. Arterial PO2 at rest is 62 mmHg. Which treatment should be initiated first?
- A Trimethoprim-sulfamethoxazole (TMP-SMX) alone
- B TMP-SMX plus adjunctive corticosteroids (prednisolone 40 mg BD) ✓
- C Pentamidine intravenously
- D Start antiretroviral therapy immediately and defer PCP treatment
Correct answer: B. TMP-SMX plus adjunctive corticosteroids (prednisolone 40 mg BD)
Explanation
This presentation is classic Pneumocystis jirovecii pneumonia (PCP). When PaO2 <70 mmHg (or A-a gradient >35 mmHg) on room air, adjunctive corticosteroids are mandatory alongside TMP-SMX, as they reduce mortality by preventing cytokine-mediated inflammatory surge during organism lysis. The standard regimen is prednisolone 40 mg twice daily for 5 days, then tapering over 21 days total. TMP-SMX alone is adequate for mild PCP (PaO2 ≥70 mmHg). Pentamidine is an alternative for TMP-SMX intolerance.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.