Sterilisation: 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

Sample item

Which method is appropriate for disinfecting a heat-sensitive flexible endoscope between patients?

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

The answer and the reasoning

C. Immersion in 2% glutaraldehyde

Heat-labile instruments such as endoscopes are processed with chemical agents. Glutaraldehyde is a high-level disinfectant that becomes sporicidal with prolonged contact and does not damage lenses or plastic.

Option by option

  • A. Autoclaving at 121 degrees Celsius

    Steam at this temperature would damage the endoscope.

  • B. Hot air oven at 160 degrees Celsius

    Dry heat at this temperature would destroy the instrument.

  • C. Immersion in 2% glutaraldehyde (correct)

    It is a liquid high-level disinfectant that is safe for delicate optics.

  • D. Boiling in water for ten minutes

    Boiling would damage the endoscope and does not kill bacterial spores.

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 C, Immersion in 2% glutaraldehyde. Heat-labile instruments such as endoscopes are processed with chemical agents.

Why is "Autoclaving at 121 degrees Celsius" not the answer?

Steam at this temperature would damage the endoscope.

Why is "Hot air oven at 160 degrees Celsius" not the answer?

Dry heat at this temperature would destroy the instrument.

Why is "Boiling in water for ten minutes" not the answer?

Boiling would damage the endoscope and does not kill bacterial spores.

What concept does this question test?

It tests Sterilisation in Microbiology. Glutaraldehyde is a high-level disinfectant that becomes sporicidal with prolonged contact and does not damage lenses or plastic.

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?

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.