Cerebrospinal fluid cell counts and chemistries in bacterial meningitis

We evaluated the records of 428 patients with bacterial meningitis to document initial cerebrospinal fluid (CSF) findings and detail their changes during therapy. Compared to patients with an initial polymorphonuclear cell predominance in the CSF, patients with initial CSF lymphocytosis had lower CSF leukocyte counts, milder CSF chemical abnormalities, and a lower frequency of positive CSF Gram stains and cultures. These findings suggest that CSF lymphocytosis may represent an early phase of infection. A low CSF leukocyte count was associated with a poor outcome, presumably reflecting an inadequate host response to infection. The CSF white cell count increased during the first 24 hours of therapy in 45% of cases. Morbidity and case fatality rates were not significantly increased in this group, suggesting that an initial rise in the CSF leukocyte count does not reflect a poor response to therapy.