The micro-organisms most commonly associated with early onset neonatal infection are group B Streptococcus (GBS), Escherichia coli, coagulase negative Staphylococcus, Haemophilus influenzae and Listeria monocytogenes.
85% of newborns with early-onset infection present within 24 hours, 5% present at 24-48 hours, and the remainder present within 48-72 hours. Onset is most rapid in premature neonates.
NICE early-onset neonatal infection guideline – National Institute for Health and Care Excellence (2010). Antibiotics for early-onset neonatal infection . CG149. London: NICE.