Lumbar puncture and cerebrospinal fluid analysis.

Examination of the CSF is the gold standard for the diagnosis of meningitis. There are a number of laboratory tests. in addition to CSF cell count, glucose concentration, Gram's stain, and bacterial culture, that are useful in identifying the organism and differentiating between bacterial and viral meningitis. These laboratory tests can be used in combination with the clinical presentation to determine which patient should be treated for bacterial meningitis while awaiting the result of CSF Gram's stain and bacterial culture.