Infectious diseases: toxic shock syndrome: practice question

A General Medicine 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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General Medicine · Infectious diseases: toxic shock syndrome

Sample item

A 22-year-old woman using a tampon develops sudden fever, diffuse sunburn-like rash, vomiting, hypotension and later peeling of the palms. What is the mechanism by which the causative toxin acts?

AIncrease in intracellular cyclic AMP in enterocytesBSuperantigen cross-linking MHC class II and the T-cell receptor beta chainCInhibition of elongation factor 2DBlockade of acetylcholine release

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

The answer and the reasoning

B. Superantigen cross-linking MHC class II and the T-cell receptor beta chain

Toxic shock syndrome toxin-1 of Staphylococcus aureus acts as a superantigen. It binds outside the antigen groove of MHC II and the variable beta region of T cells, activating a large fraction of T cells and causing a massive cytokine surge.

Option by option

A. Increase in intracellular cyclic AMP in enterocytes
Raised cyclic AMP in enterocytes is the mechanism of cholera toxin.
B. Superantigen cross-linking MHC class II and the T-cell receptor beta chain (correct)
Correct. Superantigen binding triggers polyclonal T-cell activation and cytokine storm.
C. Inhibition of elongation factor 2
Inhibition of elongation factor 2 is the mechanism of diphtheria toxin.
D. Blockade of acetylcholine release
Blockade of acetylcholine release is the mechanism of botulinum toxin.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Superantigen cross-linking MHC class II and the T-cell receptor beta chain. Toxic shock syndrome toxin-1 of Staphylococcus aureus acts as a superantigen.

Why is "Increase in intracellular cyclic AMP in enterocytes" not the answer?

Raised cyclic AMP in enterocytes is the mechanism of cholera toxin.

Why is "Inhibition of elongation factor 2" not the answer?

Inhibition of elongation factor 2 is the mechanism of diphtheria toxin.

Why is "Blockade of acetylcholine release" not the answer?

Blockade of acetylcholine release is the mechanism of botulinum toxin.

What concept does this question test?

It tests Infectious diseases: toxic shock syndrome in General Medicine. It binds outside the antigen groove of MHC II and the variable beta region of T cells, activating a large fraction of T cells and causing a massive cytokine surge.

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 Infectious diseases: toxic shock syndrome?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.