Comparison of Cerebrospinal Fluid Biomarkers for Differential Diagnosis of Acute Bacterial and Viral Meningitis with Atypical Cerebrospinal Fluid Characteristics

Objective: Several cerebrospinal fluid (CSF) biomarkers are used to distinguish between acute bacterial meningitis (BM) and viral meningitis (VM). We compared the ability of lactate and glucose (GL) in CSF and the CSF/blood GL ratio to distinguish between acute BM and VM with typical and atypical CSF characteristics. Methods: Three hundred and twenty-four CSF reports were included, which were distributed as the acute BM, VM, and normal control groups (n = 63, 139, and 122, respectively). Results: Lactate level in the CSF of acute BM group was 4-fold higher than that in the acute VM and control groups (p < 0.0001). CSF lactate presented higher specificity (92%) and negative predictive value (94%) compared to CSF GL and CSF/blood GL ratio in distinguishing acute BM and VM. Definitive acute BM or VM with atypical CSF cell characteristics was observed in 23.2 and 21.6% of samples, respectively, and these groups showed reduced performance of characteristics of all CSF biomarkers. CSF lactate showed better operational characteristics than those of CSF GL and CSF/blood GL ratio, presenting the highest positive likelihood ratio, and thus aided in the differential diagnosis of VM with atypical CSF. Conclusion: The CSF lactate assay can be routinely used in laboratories as a rapid, automated, and easy method that is independent of lactate blood levels.