NBME Microbiology Practice Test

Neonatal meningitis often stems from bacteria acquired during birth, and Escherichia coli is a leading cause, especially in early-onset disease when sepsis is present. E. coli strains that cause neonatal infection frequently have a K1 capsule and other virulence factors that help them invade the central nervous system and resist host defenses. Perinatal transmission from the maternal birth canal can lead to bacteremia, which seeds the meninges and produces meningitis in the newborn. This organism’s ability to cross the immature blood–brain barrier and its prevalence in neonatal sepsis make it a common cause of meningitis in newborns. While group B Streptococcus is also a well-known neonatal pathogen, the emphasis here is on E. coli’s high frequency and neurotropic potential in meningitis accompanying sepsis. Staphylococcus aureus is less typical for neonatal meningitis, and Listeria monocytogenes, though important, is less common than E. coli in many settings.