Clinical meaning
Neonates have an immature immune system with deficient complement activation, reduced neutrophil chemotaxis and phagocytic activity, limited immunoglobulin production (primarily relying on transplacental maternal IgG), and poor opsonization. Early-onset sepsis (EOS, within 72 hours of birth) is typically caused by vertical transmission of maternal organisms during labor and delivery. Group B Streptococcus (GBS) remains the most common pathogen, followed by E. coli. Inflammatory cascade activation causes cytokine release leading to vasodilation, capillary leak, and multi-organ dysfunction. Neonates may not mount a fever and instead present with hypothermia, reflecting their inability to generate an adequate inflammatory response.
Exam relevance
Risk factors: - Maternal GBS colonization without adequate intrapartum prophylaxis - Premature rupture of membranes (PROM) >18 hours - Prematurity (<37 weeks gestation) - Maternal chorioamnionitis (fever, uterine tenderness, foul-smelling amniotic fluid) - Low birth weight - Maternal urinary tract infection with GBS - Invasive fetal monitoring