Abstract

Sepsis is a leading cause of mortality and morbidity in neonates yet remains difficult to diagnose. This leads to widespread empiric antibiotic therapy, which can facilitate the development of antimicrobial resistance. How the dysregulated host response to infection and sepsis evolves after antibiotic treatment is poorly understood. Temporal gene expression in neonates with microbiologically confirmed sepsis, treated with the antibiotic vancomycin as part of a randomized controlled trial, was profiled to reveal a treatment-responsive gene signature. The signature exhibited a rapid reversal of the septic state, observable within 24 hours of the initiation of therapy. Unexpectedly, response rates associated with the adaptive immune system were among the fastest, and these changes were reproduced in both pediatric and adult patients with sepsis, indicating conservation and reversibility of sepsis signatures across the life course. We demonstrated how these treatment-responsive genes could be translated into a prognostic clinical measure, exhibiting strong agreement with clinical assessments. Network modeling of sepsis-responsive genes identified a signature associated with treatment comprising an early transient elevation of antimicrobial defensive genes, suggesting an impaired bactericidal response in neonatal sepsis. These findings suggest that the host response is regulated in sepsis and offer insights into early prognostic approaches for reducing antibiotic overuse.