Mycology: Trichosporon: 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: Trichosporon

Sample item

A neutropenic patient receiving caspofungin develops breakthrough fungaemia. The isolate is a yeast that forms arthroconidia, true hyphae and pseudohyphae, is urease positive, and is not encapsulated. Which organism is likely, and why did caspofungin fail?

ACandida albicans, which is intrinsically resistant to echinocandinsBTrichosporon asahii, which is intrinsically resistant to echinocandinsCAspergillus fumigatus, which is a yeast in bloodDCryptococcus neoformans, which forms arthroconidia and true hyphae

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

The answer and the reasoning

B. Trichosporon asahii, which is intrinsically resistant to echinocandins

Trichosporon species cause breakthrough fungaemia in patients on echinocandins because they are intrinsically resistant to this class. They are urease-positive basidiomycetous yeasts that form arthroconidia and hyphae, and voriconazole is preferred for treatment. Candida albicans remains susceptible to echinocandins.

Option by option

A. Candida albicans, which is intrinsically resistant to echinocandins
Candida albicans is generally susceptible to echinocandins, which are first-line therapy.
B. Trichosporon asahii, which is intrinsically resistant to echinocandins (correct)
Arthroconidia with hyphae and echinocandin breakthrough are typical of Trichosporon asahii.
C. Aspergillus fumigatus, which is a yeast in blood
Aspergillus is a mould and not a yeast, and it forms conidiophores rather than arthroconidia.
D. Cryptococcus neoformans, which forms arthroconidia and true hyphae
Cryptococcus is capsulated with narrow-based budding and does not form arthroconidia.

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.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is B, Trichosporon asahii, which is intrinsically resistant to echinocandins. Trichosporon species cause breakthrough fungaemia in patients on echinocandins because they are intrinsically resistant to this class.

Why is "Candida albicans, which is intrinsically resistant to echinocandins" not the answer?

Candida albicans is generally susceptible to echinocandins, which are first-line therapy.

Why is "Aspergillus fumigatus, which is a yeast in blood" not the answer?

Aspergillus is a mould and not a yeast, and it forms conidiophores rather than arthroconidia.

Why is "Cryptococcus neoformans, which forms arthroconidia and true hyphae" not the answer?

Cryptococcus is capsulated with narrow-based budding and does not form arthroconidia.

What concept does this question test?

It tests Mycology: Trichosporon in Microbiology. They are urease-positive basidiomycetous yeasts that form arthroconidia and hyphae, and voriconazole is preferred for treatment. Candida albicans remains susceptible to echinocandins.

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: Trichosporon?

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.