Which CSF findings are most typical in meningococcal meningitis?

• A. Low glucose, high protein, increased white blood cell count
• B. High glucose, low protein, decreased white blood cell count
• C. Normal glucose, normal protein, normal white blood cell count
• D. Low glucose, low protein, decreased white blood cell count

Answer: (A)

In bacterial meningitis, the CSF tends to show a profile of active bacterial infection with an inflammatory response. Bacteria in the CSF rapidly use glucose, so CSF glucose becomes low. The inflammatory process increases the permeability of the blood-brain barrier, allowing proteins to leak into the CSF, so protein is high. The immune system sends white cells into the CSF to fight the infection, resulting in an elevated white blood cell count, often with neutrophil predominance. So the most typical combination is low glucose, high protein, and increased white blood cell count.

The other patterns don’t fit this bacterial picture: high glucose isn’t expected because bacteria consume glucose; normal glucose or normal protein and WBC counts wouldn’t reflect an acute bacterial infection; and a low WBC count wouldn’t match the robust inflammatory response seen in meningococcal meningitis.