CALCA and infectious meningitis: The study evaluated the accuracy of laboratory results in differentiating between bacterial and non-bacterial meningitis in patients with meningitis and a negative gram stain, and concluded that CSF laboratory results have some role in distinguishing bacterial from non-bacterial meningitis, whereas serum CRP (AUC 0.81 (95% CI 0.58–0.92) and S–PCT levels (AUC 0.98, 95% CI, 0.83–1.00) are excellent predictors of bacterial meningitis, with S CPT being clearly superior (p < 0.05) [16].