Bacterial infections: 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

Sample item

A 2-week-old neonate has fever, a tender red perioral rash and sheets of superficial skin that peel with gentle rubbing, though the mucous membranes are spared. Which toxin and target are responsible?

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

The answer and the reasoning

A. Staphylococcal exfoliative toxin cleaving desmoglein 1

Staphylococcal scalded skin syndrome results from exfoliative toxins A and B from Staphylococcus aureus, which cleave desmoglein 1 in the granular layer, giving superficial blistering with a positive Nikolsky sign and sparing of the mucosae. Treatment is an anti-staphylococcal antibiotic such as flucloxacillin or cloxacillin.

Option by option

  • A. Staphylococcal exfoliative toxin cleaving desmoglein 1 (correct)

    Correct. Exfoliative toxin splits desmoglein 1 in the superficial epidermis.

  • B. Staphylococcal toxic shock syndrome toxin-1 acting as a superantigen

    TSST-1 causes a toxic shock syndrome with shock and a diffuse rash, and not a peeling split in the epidermis.

  • C. Streptococcal pyrogenic exotoxin targeting desmoglein 3

    Desmoglein 3 is the target in pemphigus vulgaris and the mucosa is affected.

  • D. Drug-induced keratinocyte apoptosis via Fas ligand

    Fas-mediated apoptosis is the mechanism of toxic epidermal necrolysis, with mucosal involvement.

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, Staphylococcal exfoliative toxin cleaving desmoglein 1. Staphylococcal scalded skin syndrome results from exfoliative toxins A and B from Staphylococcus aureus, which cleave desmoglein 1 in the granular layer, giving superficial blistering with a positive Nikolsky sign and sparing of the mucosae.

Why is "Staphylococcal toxic shock syndrome toxin-1 acting as a superantigen" not the answer?

TSST-1 causes a toxic shock syndrome with shock and a diffuse rash, and not a peeling split in the epidermis.

Why is "Streptococcal pyrogenic exotoxin targeting desmoglein 3" not the answer?

Desmoglein 3 is the target in pemphigus vulgaris and the mucosa is affected.

Why is "Drug-induced keratinocyte apoptosis via Fas ligand" not the answer?

Fas-mediated apoptosis is the mechanism of toxic epidermal necrolysis, with mucosal involvement.

What concept does this question test?

It tests Bacterial infections in Dermatology. Treatment is an anti-staphylococcal antibiotic such as flucloxacillin or cloxacillin.

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 Bacterial infections?

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.