A 38-year-old male with HIV (CD4 count 60 cells/µL) has fever, cough, and bilateral pulmonary infiltrates. Bronchoalveolar lavage shows beta-1,3-D-glucan 380 pg/mL (positive) and galactomannan ODI of 3.2. The most likely diagnosis is:
- A Pneumocystis jirovecii pneumonia (PCP)
- B Cryptococcal pneumonia
- C Invasive pulmonary aspergillosis (IPA) ✓
- D Histoplasmosis
Explanation
Galactomannan (GM) is a polysaccharide component of the Aspergillus cell wall released during hyphal invasion; BAL GM with ODI ≥1.0 is considered positive and is highly specific for invasive aspergillosis in immunocompromised patients. Beta-1,3-D-glucan is a pan-fungal marker (positive in PCP and aspergillosis) but is not galactomannan-specific. The combination of elevated BAL galactomannan and beta-glucan in a severely immunocompromised HIV patient is most consistent with IPA. Cryptococcus is detected by cryptococcal antigen (CrAg); histoplasmosis by Histoplasma urinary antigen.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.