What CSF glucose finding is typical of bacterial meningitis?

• A. Low glucose in CSF relative to serum
• B. High glucose in CSF
• C. Normal glucose
• D. Elevated lactate with normal glucose

Answer: (A)

In bacterial meningitis, glucose in the CSF falls because the bacteria and inflammatory cells consume glucose and inflammation disrupts normal glucose transport into the CSF. The typical finding is a CSF glucose that is low relative to serum—often less than about two-thirds of the serum glucose or under 40 mg/dL. This distinguishes it from viral meningitis, where CSF glucose is usually normal. Elevated lactate can accompany bacterial meningitis, but the defining glucose change is the low CSF glucose.