Clinical microbiology and hospital infection control: CSF transport: 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: CSF transport

Sample item

A CSF sample from a patient with suspected bacterial meningitis cannot reach the laboratory for three hours. How should it be handled?

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

The answer and the reasoning

D. Keep at room temperature, or incubate at 37 degrees C, never refrigerate

Fastidious organisms such as Neisseria meningitidis and Streptococcus pneumoniae die at low temperatures, so CSF for culture should not be refrigerated. It is processed promptly and kept at room temperature or 37 degrees C until then.

Option by option

  • A. Add formalin as a preservative

    Formalin kills organisms and prevents culture.

  • B. Freeze at minus 20 degrees C

    Freezing destroys the organisms and cells needed for diagnosis.

  • C. Refrigerate at 4 degrees C

    Refrigeration reduces recovery of meningococci and pneumococci.

  • D. Keep at room temperature, or incubate at 37 degrees C, never refrigerate (correct)

    Correct. Refrigeration kills fragile meningeal pathogens, so keep the sample warm.

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 D, Keep at room temperature, or incubate at 37 degrees C, never refrigerate. Fastidious organisms such as Neisseria meningitidis and Streptococcus pneumoniae die at low temperatures, so CSF for culture should not be refrigerated.

Why is "Add formalin as a preservative" not the answer?

Formalin kills organisms and prevents culture.

Why is "Freeze at minus 20 degrees C" not the answer?

Freezing destroys the organisms and cells needed for diagnosis.

Why is "Refrigerate at 4 degrees C" not the answer?

Refrigeration reduces recovery of meningococci and pneumococci.

What concept does this question test?

It tests Clinical microbiology and hospital infection control: CSF transport in Microbiology. It is processed promptly and kept at room temperature or 37 degrees C until then.

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 Clinical microbiology and hospital infection control: CSF transport?

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.