Haemophilus influenzae meningitis in an adult with initially normal cerebrospinal fluid.

We have described an adult patient with signs and symptoms of bacterial meningitis who had an initially unremarkable cerebrospinal fluid examination, but then had development of fulminant meningitis over the next 48 hours. Bacterial meningitis with normal CSF values has been previously reported in children, immunocompromised hosts, and alcoholics, and in patients with fulminant infections due to Neisseria meningitidis. We recommend that all patients with signs and symptoms compatible with bacterial meningitis and with normal results of CSF examination have close follow-up clinically over the next 48 hours with consideration of repeating the lumbar puncture.