Cell injury and adaptation: gas gangrene toxin: practice question

A Pathology 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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Pathology · Cell injury and adaptation: gas gangrene toxin

Sample item

After a contaminated road-traffic wound, a limb develops crepitus and rapidly spreading muscle necrosis. Which bacterial toxin is chiefly responsible for the tissue destruction?

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

The answer and the reasoning

C. Alpha toxin, a lecithinase

Clostridium perfringens alpha toxin is a phospholipase C (lecithinase) that destroys cell membranes, producing haemolysis, myonecrosis and vascular damage. Gas production by the organism causes crepitus.

Option by option

  • A. Exotoxin A that blocks protein synthesis

    Exotoxin A is a Pseudomonas toxin that inhibits elongation factor 2.

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

    TSST-1 is a staphylococcal superantigen producing toxic shock.

  • C. Alpha toxin, a lecithinase (correct)

    Correct. Alpha toxin is a lecithinase that lyses cell membranes.

  • D. Tetanospasmin acting on inhibitory neurones

    Tetanospasmin is the Clostridium tetani toxin causing spastic paralysis.

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.

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Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, Alpha toxin, a lecithinase. Clostridium perfringens alpha toxin is a phospholipase C (lecithinase) that destroys cell membranes, producing haemolysis, myonecrosis and vascular damage.

Why is "Exotoxin A that blocks protein synthesis" not the answer?

Exotoxin A is a Pseudomonas toxin that inhibits elongation factor 2.

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

TSST-1 is a staphylococcal superantigen producing toxic shock.

Why is "Tetanospasmin acting on inhibitory neurones" not the answer?

Tetanospasmin is the Clostridium tetani toxin causing spastic paralysis.

What concept does this question test?

It tests Cell injury and adaptation: gas gangrene toxin in Pathology. Gas production by the organism causes crepitus.

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 Cell injury and adaptation: gas gangrene toxin?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.