In suspected bacterial meningitis, which CSF finding is expected on lumbar puncture?

In suspected bacterial meningitis, which CSF finding is expected on lumbar puncture?

• A. Normal protein
• B. Elevated protein
• C. Decreased protein
• D. No cells

Answer: (B)

In suspected bacterial meningitis, the inflammatory process disrupts the blood-brain barrier, allowing plasma proteins to leak into the CSF. This leakage drives a marked rise in CSF protein, which is a hallmark of bacterial meningitis. The elevated protein accompanies other inflammatory changes, such as increased opening pressure and neutrophilic pleocytosis with low CSF glucose due to consumption by bacteria and inflammatory cells. Normal protein levels or decreased protein would not reflect this exudative, barrier-dysruption process, and having no cells would be inconsistent with meningitis.

In suspected bacterial meningitis, the inflammatory process disrupts the blood-brain barrier, allowing plasma proteins to leak into the CSF. This leakage drives a marked rise in CSF protein, which is a hallmark of bacterial meningitis. The elevated protein accompanies other inflammatory changes, such as increased opening pressure and neutrophilic pleocytosis with low CSF glucose due to consumption by bacteria and inflammatory cells. Normal protein levels or decreased protein would not reflect this exudative, barrier-dysruption process, and having no cells would be inconsistent with meningitis.