Which CSF profile is typical of acute bacterial meningitis?

• A. Low opening pressure with lymphocytic predominance and normal protein
• B. Elevated opening pressure, high neutrophils, low glucose, elevated protein
• C. Normal opening pressure, high glucose, neutrophils
• D. Elevated opening pressure, lymphocytes, high glucose, low protein

Answer: (B)

Acute bacterial meningitis produces a marked inflammatory response in the subarachnoid space, which alters CSF in a characteristic way: opening pressure is elevated, there is a neutrophil-dominant pleocytosis, glucose is low, and protein is high.

The elevated opening pressure comes from increased intracranial pressure due to inflammatory exudates and cerebral edema. The white cell count is dominated by neutrophils early on because bacteria trigger a strong neutrophilic response, whereas viral meningitis typically shows lymphocytes. Glucose in the CSF drops because bacteria and inflammatory cells consume glucose and because inflammatory processes impair glucose transport into the CSF. Protein rises because the blood-brain barrier becomes more permeable during bacterial inflammation, allowing more protein to leak into the CSF.

So the profile that best fits acute bacterial meningitis is CSF with elevated opening pressure, neutrophil predominance, low glucose, and elevated protein.