Mycology: mucormycosis and iron: 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: mucormycosis and iron

Sample item

A patient on maintenance dialysis is treated with deferoxamine for iron overload and develops rhino-orbital mucormycosis. What explains the increased risk?

ADeferoxamine suppresses neutrophil chemotaxis directlyBMucorales use the iron-deferoxamine complex as a siderophore to obtain iron for growthCDeferoxamine causes ketoacidosis similar to uncontrolled diabetesDDeferoxamine damages the nasal mucosa and removes the epithelial barrier

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

The answer and the reasoning

B. Mucorales use the iron-deferoxamine complex as a siderophore to obtain iron for growth

Free iron is normally tightly bound, which limits fungal growth. Mucorales can take up iron from ferrioxamine, so deferoxamine chelation actually feeds the fungus. Treatment of mucormycosis is liposomal amphotericin B with urgent surgical debridement and correction of the underlying risk.

Option by option

A. Deferoxamine suppresses neutrophil chemotaxis directly
Impaired neutrophil function is not the mechanism linking deferoxamine to mucormycosis.
B. Mucorales use the iron-deferoxamine complex as a siderophore to obtain iron for growth (correct)
Correct. The fungus uses ferrioxamine as an iron source.
C. Deferoxamine causes ketoacidosis similar to uncontrolled diabetes
Deferoxamine does not cause ketoacidosis, though acidosis from diabetes also impairs phagocytes.
D. Deferoxamine damages the nasal mucosa and removes the epithelial barrier
Deferoxamine has no direct toxic effect on mucosal barriers.

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, Mucorales use the iron-deferoxamine complex as a siderophore to obtain iron for growth. Free iron is normally tightly bound, which limits fungal growth.

Why is "Deferoxamine suppresses neutrophil chemotaxis directly" not the answer?

Impaired neutrophil function is not the mechanism linking deferoxamine to mucormycosis.

Why is "Deferoxamine causes ketoacidosis similar to uncontrolled diabetes" not the answer?

Deferoxamine does not cause ketoacidosis, though acidosis from diabetes also impairs phagocytes.

Why is "Deferoxamine damages the nasal mucosa and removes the epithelial barr…" not the answer?

Deferoxamine has no direct toxic effect on mucosal barriers.

What concept does this question test?

It tests Mycology: mucormycosis and iron in Microbiology. Mucorales can take up iron from ferrioxamine, so deferoxamine chelation actually feeds the fungus. Treatment of mucormycosis is liposomal amphotericin B with urgent surgical debridement and correction of the underlying risk.

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: mucormycosis and iron?

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.