Predictive Accuracy of Cord Blood C-reactive Protein and Immature-to-Total Neutrophil Ratio for Early-Onset Neonatal Sepsis in High-Risk Deliveries: A Prospective Observational Study at a Tertiary Care Center in Central India.

Background Early-onset neonatal sepsis (EOS) remains a critical contributor to neonatal mortality, particularly in low- and middle-income countries like India. Blood culture, while considered the diagnostic gold standard, is often limited by low sensitivity and delayed results. Cord blood biomarkers such as C-reactive protein (CRP) and the immature-to-total neutrophil ratio (I/T) offer promising alternatives for early, non-invasive detection of EOS. Methods This prospective observational study was conducted at a tertiary-care teaching hospital in Central India between June 2023 and December 2024. A total of 170 neonates born to mothers with one or more risk factors for EOS were enrolled. Umbilical cord blood and peripheral venous blood were analyzed for CRP, I/T ratio, complete blood count (CBC), and culture. Receiver operating characteristic (ROC) analysis was used to determine diagnostic performance and optimal cutoff values. Results Cord blood culture was positive in 25.9% of cases, with coagulase-negative Staphylococcus aureus being the most frequent isolate. Cord blood CRP ≥3.3 mg/dL and I/T ratio ≥0.155 were significantly associated with sepsis and demonstrated excellent diagnostic performance (area under the curve (AUC): 1.000 and 0.878, respectively). Comparable markers in venous blood also showed high sensitivity but slightly reduced specificity. Strong concordance was observed between cord and venous blood culture results (p<0.001). Conclusion Cord blood CRP and I/T ratio are reliable, immediate, and non-invasive markers for identifying EOS in high-risk neonates. Their inclusion in early screening protocols could significantly reduce diagnostic delays and unnecessary antibiotic exposure.