Mycology: Histoplasma antigen detection: 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.

Try it

Microbiology · Mycology: Histoplasma antigen detection

Sample item

A man with advanced HIV from eastern India has fever, weight loss, hepatosplenomegaly, pancytopenia and mucocutaneous ulcers. A Giemsa smear of the bone marrow shows small intracellular yeasts within macrophages. Which test is most useful for rapid confirmation and for monitoring treatment response?

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

The answer and the reasoning

C. Histoplasma antigen detection in urine

Progressive disseminated histoplasmosis in advanced HIV is diagnosed rapidly by detecting Histoplasma polysaccharide antigen in urine or serum, and antigen levels fall with effective treatment. Culture takes weeks, and skin tests are not useful for diagnosis in acute disease.

Option by option

  • A. Serum cryptococcal antigen titre

    Cryptococcal antigen is specific for Cryptococcus and not for Histoplasma.

  • B. Skin test with histoplasmin

    Histoplasmin skin tests indicate past exposure and are not used for diagnosis.

  • C. Histoplasma antigen detection in urine (correct)

    Correct. Urine antigen is sensitive in disseminated disease and can be followed during therapy.

  • D. India ink examination of CSF

    India ink shows encapsulated Cryptococcus in CSF, not intracellular yeasts of Histoplasma.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Histoplasma antigen detection in urine. Progressive disseminated histoplasmosis in advanced HIV is diagnosed rapidly by detecting Histoplasma polysaccharide antigen in urine or serum, and antigen levels fall with effective treatment.

Why is "Serum cryptococcal antigen titre" not the answer?

Cryptococcal antigen is specific for Cryptococcus and not for Histoplasma.

Why is "Skin test with histoplasmin" not the answer?

Histoplasmin skin tests indicate past exposure and are not used for diagnosis.

Why is "India ink examination of CSF" not the answer?

India ink shows encapsulated Cryptococcus in CSF, not intracellular yeasts of Histoplasma.

What concept does this question test?

It tests Mycology: Histoplasma antigen detection in Microbiology. Culture takes weeks, and skin tests are not useful for diagnosis in acute disease.

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: Histoplasma antigen detection?

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.