[Chronic meningococcal meningitis in an adult].

A 46-year-old woman was admitted for a four-month history of progressive cognitive and behavioral disorders. MRI revealed hydrocephalus with meningeal enhancement after gadolinium infusion. The lumbar puncture found a purulent CSF containing 305 nucleate elements per cubic millimeter including 84% altered polymorphonuclear neutrophils, protein at 4.88 g/L, and glucose at 0.5 mmol/L (for a glycemia at 6 mmol/L); there was no germ on direct examination. High dose IV cefotaxime was started together with anti-tuberculous treatment. After nine days CSF cultures were positive for Neisseria meningitidis group B. The patient improved dramatically. Only three cases of chronic N. meningitidis meningitis have been previously reported in the literature. It is important to recall that the clinical presentation of N. meningitis can be misleading, sometimes pseudo-psychiatric, without frank infectious syndrome, and may follow a chronic course.