Clinical microbiology and hospital infection control: Legionella in water systems: 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 · Clinical microbiology and hospital infection control: Legionella in water systems

Sample item

Two transplant patients develop hospital-acquired pneumonia, and Legionella is found in the hot water tanks. Which control measure is most appropriate?

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

The answer and the reasoning

B. Maintain hot water above 60 degrees Celsius with disinfection of outlets

Legionella multiplies at about 25 to 45 degrees Celsius, so storing hot water above 60 degrees and flushing and disinfecting outlets reduces colonisation. Chilled water alone does not kill organisms, and adding antibiotics is not used.

Option by option

  • A. Rely on ultraviolet light at the bedside

    Bedside ultraviolet light does not disinfect the water system.

  • B. Maintain hot water above 60 degrees Celsius with disinfection of outlets (correct)

    Correct. Hot water storage above 60 degrees limits growth.

  • C. Add antibiotics to the water supply

    Adding antibiotics to the supply is not used and promotes resistance.

  • D. Use only chilled water at 10 degrees Celsius

    Cold water does not kill Legionella and may still allow colonisation of warm sections.

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, Maintain hot water above 60 degrees Celsius with disinfection of outlets. Legionella multiplies at about 25 to 45 degrees Celsius, so storing hot water above 60 degrees and flushing and disinfecting outlets reduces colonisation.

Why is "Rely on ultraviolet light at the bedside" not the answer?

Bedside ultraviolet light does not disinfect the water system.

Why is "Add antibiotics to the water supply" not the answer?

Adding antibiotics to the supply is not used and promotes resistance.

Why is "Use only chilled water at 10 degrees Celsius" not the answer?

Cold water does not kill Legionella and may still allow colonisation of warm sections.

What concept does this question test?

It tests Clinical microbiology and hospital infection control: Legionella in water systems in Microbiology. Chilled water alone does not kill organisms, and adding antibiotics is not used.

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 Clinical microbiology and hospital infection control: Legionella in water systems?

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.