Neonatal Sepsis: Early-Onset and Late-Onset Infection

Neonatal sepsis:Systemic infection in a neonate; a medical emergency due to immature immune function and rapid progression. Early-onset sepsis (EOS): <72 hours of age (most within first 24 hours) - Cause: vertical transmission from mother - Most common organism: Group B Streptococcus (GBS) — S. agalactiae - Other organisms: E. coli, Listeria monocytogenes, S. aureus - Route: colonized maternal genital tract → ascending infection or delivery exposure Late-onset sepsis (LOS): ≥72 hours to 7 days (some define to 90 days) - Cause: nosocomial (NICU environment) or community-acquired - Most common organisms: coagulase-negative Staphylococci (CoNS), S. aureus (including MRSA), Candida, gram-negatives (Klebsiella, E. coli, Pseudomonas) - Risk factors: premature birth, invasive lines, prolonged NICU stay, mechanical ventilation Risk factors for EOS: - Maternal GBS colonization without adequate IAP (intrapartum antibiotic prophylaxis) - Prolonged ROM (>18 hours before delivery) - Maternal fever during labor (chorioamnionitis) - Preterm delivery <37 weeks (especially <35 weeks) - GBS bacteriuria in current pregnancy - Prior infant with GBS disease