Infections: bacterial, viral, fungal, parasitic: cutaneous diphtheria: 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 · Infections: bacterial, viral, fungal, parasitic: cutaneous diphtheria

Sample item

A homeless man has a chronic punched-out ulcer on the shin with a grey-brown adherent membrane that has not healed for weeks. A smear from the edge shows pleomorphic Gram-positive bacilli lying in angular, Chinese-letter arrangements. Which organism is responsible?

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

The answer and the reasoning

B. Corynebacterium diphtheriae

Cutaneous diphtheria presents as a chronic shallow ulcer with a grey membrane, mainly in poor and crowded settings and in the tropics. Club-shaped Gram-positive bacilli in palisades or Chinese letters are typical. The ulcer is also a reservoir for respiratory spread, so the patient needs antibiotics and contacts need vaccination checks.

Option by option

  • A. Pseudomonas aeruginosa

    Pseudomonas is a Gram-negative bacillus and gives green exudate and a pungent odour.

  • B. Corynebacterium diphtheriae (correct)

    Correct. Pleomorphic club-shaped bacilli in Chinese-letter arrangement identify Corynebacterium diphtheriae.

  • C. Bacillus anthracis

    Anthrax gives a painless black eschar with marked oedema, and its bacilli are large boxcar rods in chains.

  • D. Staphylococcus aureus

    Staphylococci appear as Gram-positive cocci in clusters, not as angular bacilli.

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 B, Corynebacterium diphtheriae. Cutaneous diphtheria presents as a chronic shallow ulcer with a grey membrane, mainly in poor and crowded settings and in the tropics.

Why is "Pseudomonas aeruginosa" not the answer?

Pseudomonas is a Gram-negative bacillus and gives green exudate and a pungent odour.

Why is "Bacillus anthracis" not the answer?

Anthrax gives a painless black eschar with marked oedema, and its bacilli are large boxcar rods in chains.

Why is "Staphylococcus aureus" not the answer?

Staphylococci appear as Gram-positive cocci in clusters, not as angular bacilli.

What concept does this question test?

It tests Infections: bacterial, viral, fungal, parasitic: cutaneous diphtheria in Dermatology. Club-shaped Gram-positive bacilli in palisades or Chinese letters are typical. The ulcer is also a reservoir for respiratory spread, so the patient needs antibiotics and contacts need vaccination checks.

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 Infections: bacterial, viral, fungal, parasitic: cutaneous diphtheria?

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.