INTRODUCTION

The neonate is defined as a newborn infant younger than 4 weeks old, and fever as a temperature greater than 100.4°F or 38°C. Because clinical exam is limited and because of the high risk of serious bacterial infection in this age group, all febrile neonates must be admitted for a sepsis workup and empiric antibiotic therapy.

Neonatal infections are unique, in that transmission of organisms can occur transplacentally during gestation and can present early on or be delayed by months or longer. Vertical transmission can occur in utero or during delivery. The newborn immune system is immature, increasing the susceptibility to infection. Other disease processes such as hyaline membrane disease may complicate infectious presentations. Finally, the presentation of infectious diseases in neonates is variable, often with subtle signs and symptoms.

EPIDEMIOLOGY

Neonates who are less than 2 weeks old who present to the ED have a particularly high incidence of serious illness with 10–33% requiring hospital admission. The most common diagnoses in admitted neonates include respiratory infections, sepsis, dehydration, congenital heart disease, bowel obstruction, hypoglycemia, and seizures.

Group B Streptococcus is the most common bacterial cause of neonatal sepsis in the United States. Listeria monocytogenes, Escherichia coli, Klebsiella, enterococcus, non-group D alpha hemolytic strep, and nontypeable Haemophilus influenzae are other bacterial causes.