Bacterial encephalitis

**Long definition:** An inflammatory process of the brain, frequently with evidence of meningeal involvement, due to infection by a bacterial agent. The clinical manifestations are usually acute, but may be subacute, with fever and variable combinations of convulsions, impaired mental state, and focal deficits. The spinal fluid may show a cellular reaction and elevated protein. Diagnosis is by neuroimaging, spinal fluid analysis and culture, PCR, and serologic tests.