Mycology: favus: 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: favus

Sample item

A child from a rural area has yellowish cup-shaped crusts centred on scalp hairs, with a mousy odour and scarring alopecia. Which dermatophyte is the usual cause?

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

The answer and the reasoning

C. Trichophyton schoenleinii

Favus is a chronic tinea capitis caused by Trichophyton schoenleinii, with scutula (cup-shaped crusts), mousy odour and permanent scarring alopecia. Epidermophyton floccosum does not invade hair.

Option by option

  • A. Microsporum canis

    M. canis causes ectothrix tinea capitis with bright green fluorescence under Wood's lamp.

  • B. Epidermophyton floccosum

    E. floccosum infects skin and nails but not hair.

  • C. Trichophyton schoenleinii (correct)

    Correct. Scutula, mousy odour and scarring alopecia indicate T. schoenleinii.

  • D. Trichophyton tonsurans

    T. tonsurans causes endothrix black-dot tinea capitis and not scutula.

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, Trichophyton schoenleinii. Favus is a chronic tinea capitis caused by Trichophyton schoenleinii, with scutula (cup-shaped crusts), mousy odour and permanent scarring alopecia.

Why is "Microsporum canis" not the answer?

M. canis causes ectothrix tinea capitis with bright green fluorescence under Wood's lamp.

Why is "Epidermophyton floccosum" not the answer?

E. floccosum infects skin and nails but not hair.

Why is "Trichophyton tonsurans" not the answer?

T. tonsurans causes endothrix black-dot tinea capitis and not scutula.

What concept does this question test?

It tests Mycology: favus in Microbiology. Epidermophyton floccosum does not invade hair.

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: favus?

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.