An AIDS patient (CD4 count 40 cells/μL) develops severe headache and meningism. CSF India ink preparation shows encapsulated yeast cells. The most sensitive and specific rapid diagnostic test for this infection is:
- A Latex agglutination test for cryptococcal antigen (CrAg) in CSF ✓
- B CSF culture on Sabouraud dextrose agar
- C India ink preparation of CSF
- D Mucicarmine staining of brain tissue
Explanation
The latex agglutination test (or lateral flow assay) for cryptococcal antigen (CrAg) in CSF or serum is the most sensitive and specific (>99% for both) rapid test for cryptococcal meningitis. India ink preparation is specific but less sensitive (approximately 50-80%), since it depends on the density of organisms and operator skill. Culture on Sabouraud dextrose agar is definitive but takes days to weeks. CrAg lateral flow assay can also detect cryptococcal antigenemia before symptoms develop in HIV patients, enabling pre-emptive treatment in high-burden settings.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.