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HIV-associated Pneumocystis jirovecii pneumonia — ABIM Board MCQ

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HardCorticosteroidsHIV-associated Pneumocystis jirovecii pneumoniaABIM Board

A 36-year-old man with newly diagnosed HIV infection presents with 3 weeks of progressive exertional dyspnea, nonproductive cough, and fever. His CD4 count is 38 cells/mm3. Chest CT shows diffuse bilateral ground-glass opacities, and an induced-sputum specimen is positive for Pneumocystis jirovecii. At sea level while breathing room air, arterial blood gas analysis shows pH 7.48, PaCO2 25 mm Hg, and PaO2 74 mm Hg. Intravenous trimethoprim-sulfamethoxazole was started 12 hours ago. He is hemodynamically stable and can take oral medications. Which of the following is the most appropriate adjunctive corticosteroid management?

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Correct answer: C — Give prednisone 40 mg orally twice daily on days 1–5, 40 mg daily on days 6–10, and 20 mg daily on days 11–21, beginning now

Explanation lettering: D = shown as A · A = shown as B · E = shown as C · B = shown as D · C = shown as E

This patient has HIV-associated Pneumocystis pneumonia with moderate-to-severe impairment of gas exchange. Although his PaO2 is above 70 mm Hg, the alveolar oxygen tension is approximately 118 mm Hg at sea level [150 − (PaCO2/0.8)], yielding an alveolar-arterial oxygen gradient of approximately 44 mm Hg. An A–a gradient of at least 35 mm Hg independently indicates adjunctive corticosteroids; the PaO2 criterion does not also need to be met. Prednisone should be started as soon as possible and ideally within 72 hours after anti-Pneumocystis therapy, using the 21-day regimen in option E. A is incorrect because it ignores the independently qualifying A–a gradient. B resembles the short prednisone course used for some obstructive lung disease exacerbations but is inadequate for HIV-associated Pneumocystis pneumonia. C uses the correct doses but incorrectly treats 72 hours as a required waiting period rather than the latest preferred initiation window. D is incorrect because treatment should not be deferred until the PaO2 falls below 70 mm Hg when the A–a gradient is already at least 35 mm Hg. Early adjunctive corticosteroids reduce respiratory failure and mortality in patients with HIV and moderate-to-severe Pneumocystis pneumonia.

Reference: Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents With HIV: Pneumocystis Pneumonia (Updated September 9, 2025; reviewed March 16, 2026) — https://clinicalinfo.hiv-stage.od.nih.gov/sites/default/files/guidelines/documents/adult-adolescent-oi/pneumocystis-pneumonia-adult-adolescent-oi.pdf Corticosteroids as adjunctive therapy for severe Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome: a double-blind, placebo-controlled trial (November 22, 1990) — https://pubmed.ncbi.nlm.nih.gov/2233916/