PSPN and bacterial meningitis: Some previous studies have proposed new biomarkers for bacterial meningitis, such as serum or CSF PCT (Ko et al., 2017; Reshi et al., 2017), neutrophil-to-lymphocyte ratio (Mentis et al., 2016), persephin (Stubljar et al., 2015), heparin-binding protein (Linder et al., 2011), neurofilament (Grønhøj et al., 2021), and lipocalin 2 (Thanh et al., 2021).