Bacterial infections: ecthyma gangrenosum: practice question

A Dermatology 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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Dermatology · Bacterial infections: ecthyma gangrenosum

Sample item

A neutropenic leukaemia patient has painless, round, punched-out ulcers with black necrotic centres surrounded by an erythematous halo and signs of sepsis. Which organism is most often responsible?

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

The answer and the reasoning

A. Pseudomonas aeruginosa

Ecthyma gangrenosum reflects perivascular bacterial invasion, classically by Pseudomonas aeruginosa in neutropenic patients, and indicates bacteraemia. Prompt antipseudomonal therapy is required.

Option by option

  • A. Pseudomonas aeruginosa (correct)

    Correct. Pseudomonas invades vessel walls producing necrotic ulcers.

  • B. Treponema pallidum

    Treponema causes painless chancre or gumma, not necrotic ulcers with sepsis.

  • C. Group A streptococcus

    Group A streptococcus causes simple ecthyma in the skin of healthy people but not this septic form.

  • D. Mycobacterium tuberculosis

    M. tuberculosis causes chronic ulcers like scrofuloderma.

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 Dermatology questions

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is A, Pseudomonas aeruginosa. Ecthyma gangrenosum reflects perivascular bacterial invasion, classically by Pseudomonas aeruginosa in neutropenic patients, and indicates bacteraemia.

Why is "Treponema pallidum" not the answer?

Treponema causes painless chancre or gumma, not necrotic ulcers with sepsis.

Why is "Group A streptococcus" not the answer?

Group A streptococcus causes simple ecthyma in the skin of healthy people but not this septic form.

Why is "Mycobacterium tuberculosis" not the answer?

M. tuberculosis causes chronic ulcers like scrofuloderma.

What concept does this question test?

It tests Bacterial infections: ecthyma gangrenosum in Dermatology. Prompt antipseudomonal therapy is required.

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 Bacterial infections: ecthyma gangrenosum?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.