Mycology: Blastomyces dermatitidis: 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: Blastomyces dermatitidis

Sample item

A man who returned from an outdoor trip in the Ohio River valley has chronic pneumonia and a verrucous skin lesion. Biopsy shows thick-walled yeasts about 10 micrometres across with a single broad-based bud. Which organism is it?

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

The answer and the reasoning

A. Blastomyces dermatitidis

Blastomyces dermatitidis is a thermally dimorphic fungus found in moist soil in parts of North America and, rarely, Africa and India. In tissue it forms large thick-walled yeasts with broad-based budding, causing pneumonia, verrucous skin lesions and bone disease. Itraconazole is used for mild disease and amphotericin B for severe disease.

Option by option

  • A. Blastomyces dermatitidis (correct)

    Broad-based budding of large yeasts is characteristic of Blastomyces.

  • B. Coccidioides immitis

    Coccidioides forms spherules containing endospores rather than budding yeasts.

  • C. Cryptococcus neoformans

    Cryptococcus has narrow-necked buds surrounded by a mucinous capsule.

  • D. Histoplasma capsulatum

    Histoplasma forms small yeasts about 2 to 4 micrometres within macrophages.

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 A, Blastomyces dermatitidis. Blastomyces dermatitidis is a thermally dimorphic fungus found in moist soil in parts of North America and, rarely, Africa and India.

Why is "Coccidioides immitis" not the answer?

Coccidioides forms spherules containing endospores rather than budding yeasts.

Why is "Cryptococcus neoformans" not the answer?

Cryptococcus has narrow-necked buds surrounded by a mucinous capsule.

Why is "Histoplasma capsulatum" not the answer?

Histoplasma forms small yeasts about 2 to 4 micrometres within macrophages.

What concept does this question test?

It tests Mycology: Blastomyces dermatitidis in Microbiology. In tissue it forms large thick-walled yeasts with broad-based budding, causing pneumonia, verrucous skin lesions and bone disease. Itraconazole is used for mild disease and amphotericin B for severe 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: Blastomyces dermatitidis?

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.