Patient is 49 yo F who presents to ED with few days of fever (T max 102F), progressive headache, neck stiffness. Patient denies any travel, rashes, sick contacts. Pt complains she can’t be in a well lit room or go outside without pain. You have a high suspicion for meningitis and so perform an LP.
CSF shows as follows:
WBC 100/mm3 (60% N, 35%L)
Glucose 40 (serum glucose 100)
Aside from a gram stain and culture, are there any other tools to help differentiate between viral and bacterial meningitis?
Cerebral Spinal Fluid Lactate has been more extensively investigated in the adult population. Some studies have found it to have a sensitivity of 93-94% and specificity of 96-97% at a cut-off level  with the cutoff being described between of 3.8 mmol/L  and 3.9 mmol/L  in the adult population. In pediatrics, a recent article (studying patients from 1 mo to 15yr) found a cutoff of 3.0 mmol/L to be optimal cutoff in distinguishing bacterial and viral meningitis but recommend its use in conjunction with the validated Bacterial Meningitis Scoring system .
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