Mycology: cryptococcosis: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Mycology: cryptococcosis

Sample item

A lung biopsy from an HIV-positive patient shows round yeasts surrounded by clear halos. Which special stain colours the polysaccharide capsule of the yeast and helps confirm Cryptococcus neoformans in tissue?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Mucicarmine

Mucicarmine stains the acidic polysaccharide of the cryptococcal capsule red, which helps to distinguish Cryptococcus from other yeasts in tissue. India ink is used on cerebrospinal fluid to show the unstained capsule, and cryptococcal antigen detection by latex agglutination or lateral flow is more sensitive. Gomori methenamine silver stains the fungal cell wall black but not the capsule.

Option by option

  • A. Congo red

    Congo red demonstrates amyloid rather than fungal capsules.

  • B. Gomori methenamine silver

    Methenamine silver stains the yeast wall but not the capsule.

  • C. Giemsa

    Giemsa is used for blood parasites and Histoplasma but does not highlight a capsule.

  • D. Mucicarmine (correct)

    Correct. Mucicarmine stains the capsule red in tissue sections.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Mucicarmine. Mucicarmine stains the acidic polysaccharide of the cryptococcal capsule red, which helps to distinguish Cryptococcus from other yeasts in tissue.

Why is "Congo red" not the answer?

Congo red demonstrates amyloid rather than fungal capsules.

Why is "Gomori methenamine silver" not the answer?

Methenamine silver stains the yeast wall but not the capsule.

Why is "Giemsa" not the answer?

Giemsa is used for blood parasites and Histoplasma but does not highlight a capsule.

What concept does this question test?

It tests Mycology: cryptococcosis in Microbiology. India ink is used on cerebrospinal fluid to show the unstained capsule, and cryptococcal antigen detection by latex agglutination or lateral flow is more sensitive. Gomori methenamine silver stains the fungal cell wall black but not the capsule.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Mycology: cryptococcosis?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.