Neonatal sepsis: any role for procalcitonin as a diagnostic marker?

Abstract Introduction In low and middle-income countries, a key driver of neonatal morbidity and mortality is neonatal sepsis. Rapid and precise diagnosis of neonatal sepsis remains a critical challenge due to limited laboratory facilities. Blood culture results, the diagnostic gold standard, are often unavailable or delayed; therefore, procalcitonin (PCT) has been considered as a potential inflammatory biomarker of bacterial infection.This study assessed the diagnostic performance of PCT in neonates with sepsis at the Federal Teaching Hospital, Owerri, Nigeria. Methods This cross-sectional study recruited 75 neonates aged 0–28 days with clinical suspicion of sepsis between June 2023 and February 2024. Sociodemographic and clinical data were obtained using a structured questionnaire, serum PCT levels were measured using Enzyme-linked immunosorbent assay (ELISA) and blood culture was performed as the gold standard. The primary outcome was the diagnostic accuracy of PCT for neonatal sepsis. Secondary outcomes included comparison of diagnostic performance between early-onset neonatal sepsis (EONNS) and late-onset neonatal sepsis (LONNS), and description of microbial isolates. Diagnostic indices (sensitivity, specificity, positive predictive value (PPV), negative predictive value, NPV) were calculated at different PCT thresholds. Receiver operating characteristic (ROC) curves were analysed to determine the area under the curve (AUC). Results Of the 75 neonates, 55 (73.3%) had culture-confirmed sepsis and 32 (58.2%) early-onset neonatal sepsis. Serum PCT levels were not normally distributed (Kolmogorov–Smirnov test, p  < 0.001) and were summarized using medians and interquartile ranges. At a PCT cut-off of ≥ 2 ng/mL, sensitivity and NPV were 72.7% and 57.1% respectively while specificity and PPV remained 100% for all neonates. The AUC for PCT was significantly higher in EONNS (0.964, 95% CI: 0.910–1.000) compared to LONNS (0.788, 95% CI: 0.638–0.938). Gram-negative organisms (63.6%) were the most common isolates, mainly Escherichia coli (34.5%). Conclusion Serum procalcitonin demonstrates high specificity for culture-confirmed neonatal sepsis at a cut-off of ≥ 2.0 ng/mL in this cohort, with better diagnostic performance in early-onset disease. These findings apply to the studied population and cut-off thresholds. PCT measurement integration in Nigeria can be a priceless tool for guiding rational antibiotic therapy; particularly where rapid confirmation of sepsis is critical to improving neonatal survival outcomes.