The use of C-reactive protein from cerebrospinal fluid for differentiating meningitis from other central nervous system diseases.

C-reactive protein (C-RP) determinations were performed by using the latex slide agglutination test on cerebrospinal fluid (CSF) from 235 patients. The patients were categorized into the following groups: bacterial meningitis (n = 74); viral meningitis (n = 10); fever without bacterial meningitis (n = 80); neurological symptoms without infection (n = 25); intracranial hemorrhage (n = 10); increased intracranial pressure that was secondary to pseudotumor cerebri or hydrocephalus (n = 16); and malignancies (n = 20). On the initial lumbar puncture, the C-RP was positive in 97% (72 of 74) of the patients in group 1, as compared with 0% (0 of 10), 6% (5 of 80), 20% (5 of 25), 50% (5 of 10), 6% (1 of 16), and 30% (6 of 20) in groups 2-7, respectively (P less than .0001). The C-RP test was able to detect bacterial meningitis with a sensitivity of 97% (72 of 74), a specificity of 86% (139 of 161), a positive predictive value of 77% (72 of 94), and a negative predictive value of 99% (139 of 141). These data indicate that C-RP determinations performed on CSF are useful and rapid clinical tests for the exclusion of the presence of bacterial meningitis in a patient.