National Center for Biotechnology Information NCBI NLM MEDLINE humans pubmed abstract nih national institutes of health national library of medicine research support non-u.s. gov't female male adolescent young adult Child Infant Comparative Study newborn preschool Retrospective Studies DNA sensitivity and specificity sepsis / mortality severity of illness index meningitis false negative reactions neisseria meningitidis / isolation & purification* sepsis / microbiology neisseria meningitidis / genetics bacterial / isolation & purification meningococcal / microbiology pmid:30865671 pmc6415896 doi:10.1371/journal.pone.0212922 sara guiducci maria moriondo chiara azzari bacterial load / methods* cell culture techniques / statistics & numerical data meningococcal / diagnosis* meningococcal / mortality real-time polymerase chain reaction / statistics & numerical data sepsis / diagnosis*