Translational research and biomarkers in neonatal sepsis

As neonatal sepsis is a severe condition, there is a call for reliable biomarkers to differentiate between infected and noninfected newborns. Although blood culture has been considered as the gold standard, this analysis is still too slow and limited by false negative results. Use of CRP is hampered by a physiological 3-day increase, resulting in a low sensitivity to detect sepsis at an early stage. A moderate diagnostic accuracy of other acute phase proteins has been demonstrated (serum amyloid A, procalcitonin, lipopolysaccharide binding protein, mannose binding lectin and hepcidin). In neonatal sepsis, changed chemokine/cytokine levels are observed before those of acute phase reactants. High IL-6, IL-8, IL-10 and TNF-α concentrations are detected in infected infants. Soluble interleukin-2 receptor has been used to identify bacteremia, whereas low plasma RANTES concentrations are characteristic for septicemia. Several cell adhesion molecules contribute to the pathogenesis of sepsis. As an upregulated CD64 expression on granulocytes is found within 1-6h after bacterial invasion, serial CD64 measurements could guide antibiotic therapy. An increased CD11b/CD18 density can improve the diagnosis, and a positive correlation between CD11b and the severity of systemic inflammation has been reported. An early increase in sCD14-ST presepsin is also observed during sepsis, whereas high sTREM-1 values in early-onset neonatal sepsis (EOS) have been associated with mortality. Biomarkers resulting from proteomics are also promising. A 4-biomarker 'mass restricted' score has been validated as diagnostic for intra-amniotic infection and/or inflammation. S100A8 in amniotic fluid is a strong predictor of an increased incidence of EOS. Proteomic analysis of cord blood has revealed altered protein expression patterns. The ApoSAA score is useful for identifying sepsis and could guide prescription of antibiotics. (1)H-NMR and GC-MS metabolomics allow to diagnose septic shock, which is associated with increased concentrations of 2-hydroxybutyrate, 2-hydroxyisovalerate, 2-methylglutarate, creatinine, glucose and lactate.