Infectious diseases: anthrax capsule: 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: anthrax capsule

Sample item

A wool sorter has a painless black necrotic ulcer on the forearm with marked surrounding oedema. Smear shows large non-motile gram-positive bacilli in chains with square ends. Which virulence factor allows the organism to resist phagocytosis?

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

The answer and the reasoning

A. Poly-D-glutamic acid capsule

Bacillus anthracis has a unique polypeptide capsule of poly-D-glutamic acid that protects it from phagocytosis. The toxin complex consists of protective antigen, which binds host cells and carries lethal factor and edema factor into the cell, causing cell damage and tissue oedema.

Option by option

  • A. Poly-D-glutamic acid capsule (correct)

    Correct. The capsule of poly-D-glutamic acid prevents phagocytosis.

  • B. Protective antigen

    Protective antigen is the binding component that allows entry of the toxins.

  • C. Lethal factor

    Lethal factor is a protease that cleaves signalling kinases and causes cell death.

  • D. Edema factor

    Edema factor is an adenylate cyclase that raises cyclic AMP and causes the oedema.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Poly-D-glutamic acid capsule. Bacillus anthracis has a unique polypeptide capsule of poly-D-glutamic acid that protects it from phagocytosis.

Why is "Protective antigen" not the answer?

Protective antigen is the binding component that allows entry of the toxins.

Why is "Lethal factor" not the answer?

Lethal factor is a protease that cleaves signalling kinases and causes cell death.

Why is "Edema factor" not the answer?

Edema factor is an adenylate cyclase that raises cyclic AMP and causes the oedema.

What concept does this question test?

It tests Infectious diseases: anthrax capsule in General Medicine. The toxin complex consists of protective antigen, which binds host cells and carries lethal factor and edema factor into the cell, causing cell damage and tissue oedema.

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: anthrax capsule?

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.