Supplementary Material for: The Use of S100B and Tau Protein Concentrations in the Cerebrospinal Fluid for the Differential Diagnosis of Bacterial Meningitis: A Retrospective Analysis

Background: Patients with meningitis are often difficult to classify into bacterial (BM) or benign viral (VM) meningitis. To facilitate the differential diagnosis, S100B and Tau protein in the cerebrospinal fluid (CSF) were measured and compared with standard laboratory parameters. Methods: S100B_CSF, Tau_CSF, and routine parameters (CSF leukocyte count, protein_CSF, lactate_CSF, serum C-reactive protein, blood leukocyte count and body temperature) were analyzed in 33 patients with microbiologically confirmed BM and in 19 with VM. Their classification accuracy, sensitivity and specificity were studied by receiver operating characteristic (ROC) curves. Results: S100B_CSF concentrations were higher in BM than in VM patients (p = 0.03) and showed a promising accuracy (90%) for the differential diagnosis of BM versus VM. Its discriminative properties were comparable to routine parameters. Of all parameters, S100B_CSF showed the highest specificity (100%) with an optimal cut-off of 3.1 ng/ml. Tau_CSF concentrations were useless for the discrimination (p = 0.64). Conclusions: In contrast to Tau_CSF, S100B_CSF concentrations ≧3.1 ng/ml are promising to discriminate bacterial from viral meningitis.