EXCESS GLUTAMATE IN THE CEREBROSPINAL-FLUID IN BACTERIAL-MENINGITIS

We investigated possible neurotoxic components in the cerebrospinal fl uid (CSF) of patients with bacterial meningitis. On murine cerebellar neuronal cell cultures, CSF exerted a dose-dependent toxic effect, whi ch was attenuated by the NMDA receptor antagonist MK-801. Glutamate co ncentrations in the CSF of patients with bacterial meningitis were mea sured by an enzymatic assay and found to be significantly elevated (p < 0.0001) as compared to viral meningitis and non-inflammatory neurolo gical diseases. The concentration of glutamate in the CSF of patients with bacterial meningitis varied considerably and correlated with the severity of the disease as scored by the Glasgow Coma Scale. Cells in the CSF, mainly comprising polymorphonuclear granulocytes, did not rel ease any glutamate into the culture medium, whereas brood monocytes pr oduced remarkable amounts. These findings implicate an important role of monocytic inflammatory cells in bacterial meningitis by the release of glutamate, which may contribute to neuronal cell death.