The differential diagnosis of bacterial and aseptic meningitis using cerebrospinal fluid laboratory tests.

The lactate, lysozyme, C-reactive protein and serum amyloid-A protein concentrations in cerebrospinal fluid were measured in 11 patients with bacterial meningitis, 27 patients with aseptic meningitis and in 31 control patients. The mean concentration of each parameter was significantly higher (p less than or equal to 0.0001) in patients with bacterial meningitis than in those with aseptic meningitis or those without meningitis. The reliability of these tests in the differential diagnosis of bacterial and aseptic meningitis was compared with leucocyte counts in cerebrospinal fluid. Gram staining for bacteria, and protein and glucose levels. The cerebrospinal fluid lactate level proved to be more sensitive than lysozyme. C-reactive protein or serum amyloid-A protein and had a high degree of specificity.