CSF analysis in a 25-year-old with acute bacterial meningitis typically shows which combination?

• A Normal protein, normal glucose, lymphocytic pleocytosis 50–500 cells/µL
• B Mildly raised protein, normal glucose, RBC count >100/µL (xanthochromia)
• C Raised protein, very low glucose (<40% of blood glucose), polymorphonuclear pleocytosis >1000 cells/µL ✓
• D Very high protein (>500 mg/dL), normal cells, cobweb clot formation

Explanation

Acute bacterial meningitis produces a characteristic CSF profile: markedly elevated protein (>100 mg/dL), very low glucose (CSF:serum ratio <0.4), and neutrophilic (polymorphonuclear) pleocytosis often exceeding 1000 cells/µL. This contrasts with viral (aseptic) meningitis: mildly raised protein, normal glucose, lymphocytic pleocytosis 50–500 cells/µL. Subarachnoid haemorrhage shows xanthochromia with RBCs. Very high protein with cobweb clot and lymphocytic pleocytosis is characteristic of tuberculous meningitis. Gram stain is positive in 60–80% of bacterial cases.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.