Myxovirus resistance protein A in neonates presenting with late onset sepsis including respiratory manifestations.

BACKGROUND: Late onset sepsis is a life-threatening condition wich occurs after 72 hours of birth caused by systemic infections that prompt a cascade of often fatal inflammatory immune responses. It has a broad range of symptoms and signs including respiratory signs like apnea, bradypnoea, tachypnea and/or increase in ventilatory support and may present with temperature instability, feeding intolerance, tachycardia, bradycardia, hypotension, poor perfusion, lethargy, hypotonia and seizures. AIM OF THE WORK: To determine the diagnostic value of monocyte MxA expression in neonates to differentiate between viral and bacterial infections. To determine MxA/CRP ratio in viral infection in neonates. PATIENTS AND METHODS: The study was conducted as a cross-sectional study in the Neonatal Intensive Care Unit at the Children's Hospital & Maternity Hospital, Ain Shams University, Cairo, Egypt, over a period of 6 to 9 months. RESULTS: This study analyzed neonates with late-onset sepsis (LOS) to distinguish bacterial from viral infections using the Myxovirus Resistance Protein A (MxA) biomarker. Bacterial infections were predominant (54.0%), with Klebsiella as the most common pathogen, while RSV accounted for 28.0% of viral infections. Co-infections (6.0%) posed additional diagnostic challenges. LOS was prevalent among preterm and low-birth-weight neonates, consistent with global trends. Fever was more common in bacterial cases, though not a reliable indicator. MxA levels and MxA/CRP ratios were significantly higher in viral infections, with ROC analysis showing both biomarkers had 100% sensitivity and specificity for differentiating between bacterial and viral causes. An MxA cut-off >150.30 and MxA/CRP ratio >8.37 offered optimal diagnostic accuracy. The findings emphasize MxA's value in guiding treatment, reducing unnecessary antibiotic use, and improving clinical outcomes. The study also highlights the importance of GBS screening and the growing concern over multidrug-resistant pathogens in neonatal care settings. CONCLUSION: This study supports the use of MxA and the MxA/CRP ratio as effective diagnostic tools for distinguishing between viral and bacterial infections in neonates with late-onset sepsis. The significant differences in clinical, laboratory, and radiological findings between the two infection types underscore the importance of integrating multiple diagnostic approaches.