Ideally, a good biomarker would have 100% sensitivity for the diagnosis of bacterial meningitis, together with an acceptable specificity [38]; however, when used alone, available biomarkers (PCT, CRP, IFN-Υ, etc.)have sensitivities and specificities that do not appear high enough to base a therapeutic decision on their results given the risks incurred in case of a false-negative test [44,45]. The gene discussed is CRP; the disease is bacterial meningitis.