Sterilisation: Bowie-Dick test: practice question

A Microbiology 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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Microbiology · Sterilisation: Bowie-Dick test

Sample item

A central sterile services department runs a Bowie-Dick test pack in an empty pre-vacuum (porous load) autoclave. After the cycle, the indicator sheet shows a pale unchanged area in the centre while the edges have changed colour. What does this indicate?

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

The answer and the reasoning

B. Inadequate air removal or steam penetration

The Bowie-Dick test is a daily check of air removal and steam penetration in pre-vacuum autoclaves. A uniform colour change shows that steam reached all parts of the pack. A pale centre means an air pocket remained, usually from a vacuum pump failure or a door gasket leak, so the machine must not be used until it is serviced.

Option by option

  • A. Contamination of the pack with bacterial spores

    The chemical indicator sheet does not detect spores; spore testing needs a biological indicator.

  • B. Inadequate air removal or steam penetration (correct)

    A pale centre shows that trapped air prevented steam from reaching the middle of the pack.

  • C. Satisfactory sterilisation conditions

    Uniform colour change would show satisfactory conditions; a patchy change means the test failed.

  • D. Excessive temperature in the chamber

    Excess temperature would not leave the centre unchanged, and the test does not measure overheating.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is B, Inadequate air removal or steam penetration. The Bowie-Dick test is a daily check of air removal and steam penetration in pre-vacuum autoclaves.

Why is "Contamination of the pack with bacterial spores" not the answer?

The chemical indicator sheet does not detect spores; spore testing needs a biological indicator.

Why is "Satisfactory sterilisation conditions" not the answer?

Uniform colour change would show satisfactory conditions; a patchy change means the test failed.

Why is "Excessive temperature in the chamber" not the answer?

Excess temperature would not leave the centre unchanged, and the test does not measure overheating.

What concept does this question test?

It tests Sterilisation: Bowie-Dick test in Microbiology. A uniform colour change shows that steam reached all parts of the pack. A pale centre means an air pocket remained, usually from a vacuum pump failure or a door gasket leak, so the machine must not be used until it is serviced.

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 Sterilisation: Bowie-Dick test?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.