Bacteriology: CSF interpretation: 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 · Bacteriology: CSF interpretation

Sample item

A 35-year-old has a 3-week history of headache and vomiting, and now has a sixth cranial nerve palsy. CSF shows 150 cells per microlitre (90% lymphocytes), glucose 25 mg/dL with blood glucose 100 mg/dL, protein 200 mg/dL, and a cobweb coagulum on standing. What is the most likely diagnosis?

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

The answer and the reasoning

D. Tuberculous meningitis

Subacute onset with cranial nerve palsy, lymphocytic pleocytosis, low glucose, markedly raised protein and a cobweb coagulum is classic for tuberculous meningitis. Viral meningitis has normal glucose, and pyogenic meningitis has thousands of neutrophils. Guillain-Barre syndrome has raised protein with few cells.

Option by option

  • A. Guillain-Barre syndrome

    Guillain-Barre syndrome shows albuminocytological dissociation with a normal glucose and few cells.

  • B. Viral meningitis

    Viral meningitis has a lymphocytic picture but normal glucose and mildly raised protein.

  • C. Acute pyogenic meningitis

    Acute pyogenic meningitis presents over hours to days with neutrophils in the thousands.

  • D. Tuberculous meningitis (correct)

    Correct. This combination of findings is typical for tuberculous meningitis.

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, Tuberculous meningitis. Subacute onset with cranial nerve palsy, lymphocytic pleocytosis, low glucose, markedly raised protein and a cobweb coagulum is classic for tuberculous meningitis.

Why is "Guillain-Barre syndrome" not the answer?

Guillain-Barre syndrome shows albuminocytological dissociation with a normal glucose and few cells.

Why is "Viral meningitis" not the answer?

Viral meningitis has a lymphocytic picture but normal glucose and mildly raised protein.

Why is "Acute pyogenic meningitis" not the answer?

Acute pyogenic meningitis presents over hours to days with neutrophils in the thousands.

What concept does this question test?

It tests Bacteriology: CSF interpretation in Microbiology. Viral meningitis has normal glucose, and pyogenic meningitis has thousands of neutrophils. Guillain-Barre syndrome has raised protein with few cells.

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 Bacteriology: CSF interpretation?

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.