Paper II — 2025 March (Supplementary (SAY)) (2019 Scheme) — Q13
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Paper II
2025 March (Supplementary (SAY)) (2019 Scheme) · 100 marks · 180 min
Question
Name the most common yeast causing meningitis in a HIV positive patient. Name a special stain
used for its detection in CSF sample. Draw a neat labelled diagram of its appearance under the
microscope using the special stain. Name one rapid test to identify this yeast in the CSF sample.
(1+1+1+1)
Q134 marksShort Answers
Answer
Most common yeast causing meningitis in an HIV-positive patient: Cryptococcus neoformans.
Special stain used for detection in CSF: India ink preparation.
Appearance under the microscope (India ink stain) — description: the yeast appears as a round-to-oval cell body surrounded by a wide, clear, unstained halo (representing the thick polysaccharide capsule, which excludes the black ink particles) against the black background of the India ink itself; budding (a single or occasionally narrow-based bud) may be seen. (A hand-drawn labelled diagram would depict a central round yeast cell body with a surrounding wide, clear halo/capsule against a stippled black background, with a bud shown emerging from one pole; described here in text form as diagrams cannot be rendered in this format.)
Rapid test to identify the yeast in CSF: the Cryptococcal Antigen (CrAg) test — detection of capsular polysaccharide antigen in CSF (or serum) by latex agglutination or lateral flow immunoassay (LFA); more sensitive than India ink and now the preferred rapid diagnostic test, also used for screening asymptomatic HIV patients with low CD4 counts.
