The review included twenty-two studies with a total of 2058 patients; diagnostic accuracy of S–PCT and CSF PCT was assessed using the bivariate model and analysis showed that PCT is a useful biomarker for the diagnosis of bacterial meningitis: CSF PCT had 0.86 specificity and 0.8 sensitivity, whereas S–PCT had 0.97 specificity and 0.95 sensitivity [30]. This evidence concerns the gene CALCA and bacterial meningitis.