Table 1.

Criteria for an ideal biomarker or test for the diagnosis of neonatal sepsis (63).

Clinical properties

1. Such biomarkers should have a well-defined cut-off value and a sensitivity and negative predictive value approaching 100% for “ruling out” LOS (but simultaneously having high specificity and positive predictive value >85%) 2. Detect infection early (i.e., at clinical presentation) 3. Identify a specific pathogen or a category of pathogens (e.g. viral, bacterial, and fungal organisms; gram-positive organisms vs. gram-negative organisms; a specific species of pathogen) 4. Monitor disease progress and guide antimicrobial treatment (e.g. bacterial antibiotic resistance gene detection) 5. Predict the disease severity at the onset of infection (e.g. identify the type of virulent pathogen, predict DIC at the onset of disease presentation) 6. Predict prognosis (i.e., mortality)

Laboratory properties

1. Stable compound that may allow an adequate time window for specimen collection within normal working hours (i.e., sustained increase or decrease in biomarker level for at least 24 h) or easy storage of the specimen without significant decomposition of the active compound until laboratory processing 2. Quantitative determination of biomarker concentration 3. Automatic and easy method of measurement 4. Quick turnaround time (i.e., specimen collection, transport, laboratory processing time, and reporting of results to clinicians within 6 h) 5. Small volume of specimen (i.e., <0.5 mL blood) 6. Daily or on-demand availability of testing in clinical laboratories 7. Low-cost test that can be used as a routine measurement