Current Evidence The most common bacterial and viral pathogens are listed according to age in Table 122.2 The relative rates of meningitis, especially bacterial meningitis, remain highest in the neonatal age group Clinical Recognition Most patients present with fever, evidence of meningeal irritation, and increased ICP from diffuse cerebral edema or hydrocephalus with CSF obstruction at the basilar cisterns However, clinical manifestations may be nonspecific Diagnostic testing Infection of the subarachnoid space can be diagnosed by sampling the CSF through a lumbar puncture A CT scan or quick brain MRI should be performed prior to lumbar puncture to rule out hydrocephalus Lumbar puncture in the setting of untreated hydrocephalus may precipitate life-threatening herniation Management Suspected bacterial meningitis is a medical emergency and administration of appropriate antibiotic therapy should not be deferred if lumbar puncture cannot be performed Placement of an ICP monitor is controversial even in the presence of a poor neurologic examination or cerebral edema Monitoring ICP has not been shown to improve outcomes in these patients Maintenance of cerebral perfusion, by avoiding hypotension, not the direct treatment of elevated ICP, improves outcomes The most important prognostic factor for patients with meningitis is prompt and appropriate antimicrobial treatment