Median S–PCT level was 6.45 ng/mL (0.25–43.76 ng/mL) in patients with bacterial meningitis vs. 0.27 ng/mL (0.05–0.44 ng/mL) in patients with viral meningitis, and the authors concluded that S–PCT and CSF PCT concentrations >0.5 ng/mL seem to be reliable indicator of bacterial CNS infection [9]. This evidence concerns the gene CALCA and viral meningitis.