Mycology: tinea capitis: 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: tinea capitis

Sample item

A 7-year-old boy has a round patch of scaly alopecia with broken lusterless hairs. Under a Wood's lamp the hairs show bright green fluorescence, and microscopy shows a sheath of small spores around the hair shaft. Which organism and treatment fit best?

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

The answer and the reasoning

C. Microsporum canis, treated with oral griseofulvin

Ectothrix infection with bright green fluorescence is characteristic of Microsporum species, such as M. canis acquired from cats and dogs. Tinea capitis needs systemic therapy because topical drugs do not reach the follicle, and oral griseofulvin for several weeks is the traditional drug of choice for Microsporum. Trichophyton tonsurans, by contrast, is endothrix and does not fluoresce.

Option by option

  • A. Candida albicans, treated with oral nystatin

    Candida does not form ectothrix sheaths on hairs, and oral nystatin is not absorbed.

  • B. Trichophyton rubrum, treated with topical miconazole alone

    T. rubrum seldom causes tinea capitis and does not fluoresce, and topical therapy alone fails for hair infection.

  • C. Microsporum canis, treated with oral griseofulvin (correct)

    Correct. Green fluorescence with an ectothrix pattern points to Microsporum, and oral therapy is needed.

  • D. Malassezia furfur, treated with selenium sulfide shampoo

    Malassezia causes pityriasis versicolor and is not an ectothrix hair pathogen.

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, Microsporum canis, treated with oral griseofulvin. Ectothrix infection with bright green fluorescence is characteristic of Microsporum species, such as M.

Why is "Candida albicans, treated with oral nystatin" not the answer?

Candida does not form ectothrix sheaths on hairs, and oral nystatin is not absorbed.

Why is "Trichophyton rubrum, treated with topical miconazole alone" not the answer?

T. rubrum seldom causes tinea capitis and does not fluoresce, and topical therapy alone fails for hair infection.

Why is "Malassezia furfur, treated with selenium sulfide shampoo" not the answer?

Malassezia causes pityriasis versicolor and is not an ectothrix hair pathogen.

What concept does this question test?

It tests Mycology: tinea capitis in Microbiology. canis acquired from cats and dogs. Tinea capitis needs systemic therapy because topical drugs do not reach the follicle, and oral griseofulvin for several weeks is the traditional drug of choice for Microsporum. Trichophyton tonsurans, by contrast, is endothrix and does not fluoresce.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: tinea capitis?

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.