A 48-year-old man with HIV (CD4 count 90 cells/μL) presents with 3 weeks of cough, low-grade fever, and dyspnea. CXR shows bilateral diffuse interstitial infiltrates predominantly in the perihilar regions. LDH is markedly elevated at 620 IU/L. Bronchoalveolar lavage with silver staining shows cup-shaped organisms. What is the specific treatment?
- A Trimethoprim-sulfamethoxazole (TMP-SMX) plus adjunctive corticosteroids if PaO2 <70 mmHg ✓
- B Liposomal amphotericin B
- C Fluconazole 400 mg daily
- D Clindamycin plus primaquine as first-line
Explanation
Pneumocystis jirovecii pneumonia (PCP) is the most common AIDS-defining opportunistic infection at CD4 <200 cells/μL. It classically presents with bilateral perihilar interstitial infiltrates, elevated LDH (a marker of disease severity), and Gomori methenamine silver (GMS) staining showing cup-shaped or crescent cysts. First-line treatment is TMP-SMX (15–20 mg/kg/day of TMP component in divided doses for 21 days). Adjunctive systemic corticosteroids are added if PaO2 <70 mmHg or A-a gradient >35 mmHg to reduce inflammatory injury and mortality. Clindamycin-primaquine is an alternative for mild-moderate disease or 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.