The primary goal of this proposed research is to develop a rapid point-of-care (POC) test, based on Inter-alpha inhibitor Proteins (IAIP) levels in blood, that assesses the risk of neonatal sepsis (NS) and/or necrotizing enterocolitis (NEC) in infants. NS and NEC are associated with high mortality, serious morbidity, and adverse neuro-developmental outcomes. The currently available biomarkers are not sensitive and specific enough for early detection of NS and NEC to reliably guide clinical decisions for continuation of antibiotic treatment in infants whose conventional test results are uninformative. IAIP are found in human plasma at high concentrations and are rapidly depleted during acute severe infection/systemic inflammation. In the recently completed SBIR Phase II study, we successfully developed a prototype for a rapid test (RT) that accurately measures the IAIP level in blood within 15 minutes, with comparable results to a 6-hour laboratory ELISA. Using the newly developed RT, we confirmed that IAIP level is a sensitive and specific predictive marker for NS and NEC using blood samples collected from enrolled infants in two quaternary care NICUs. The AUC of the ROC analysis comparing infants with positive and negative blood cultures was 0.991 and the sensitivity of 96.3% and specificity of 94.6% (p< 0.001). A similar high predictive value of IAIP was observed in infants with NEC. Overall, the IAIP test has remarkably high positive and negative predictive values in detecting NS (93% and 98%, respectively) or when NS and NEC are combined (94% and 95%). In this continuation Phase II-B project, we will further validate the role and utility of this sensitive host-response biomarker in antibiotic stewardship and compare head-to-head its performance against Procalcitonin (PCT) and C-Reactive Protein (CRP). We hypothesize that IAIP levels will be significantly reduced in infants with culture proven NS and/or NEC (Bell’s Stage >2) and IAIP is more sensitive than PCT and CRP in detecting NS and NEC in suspected infants that are not confirmed by blood culture or radiographs. The IAIP level will remain normal or not be significantly altered during non-infectious/non-systemic disturbances that generally do not warrant antibiotic treatment. The IAIP-RT would be useful in reducing exposure to unnecessary long-term, broad-spectrum antibiotics to these infants. The specific aims are: 1) Process validation and scale-up manufacturing to produce clinical-grade IAIP-RT batches for implementation of regulatory strategy; 2) Confirm and validate the ROC characteristics and cut-off value of the IAIP-RT in larger clinical samples of NS and NEC; 3a) Perform a comparison study of IAIP test head-to-head with PCT and CRP during clinical evaluation of NS and NEC; 3b) Assess the potential for antibiotic discontinuation in infants with negative blood culture, negative NEC symptoms AND normal IAIP level and 4) Compare the Natural History of longitudinally collected IAIP lev...