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Neonatal sepsis.


Review risk factors, clinical presentation, evaluation, and treatment options for sepsis in neonates.



Sepsis is a clinical syndrome caused by invasion of a microbial pathogen into the bloodstream. Early-onset neonatal sepsis (EOS) is defined as onset of symptoms before 7 days of age, while late-onset neonatal sepsis (LOS) refers to the onset of symptoms after 7 days and up to 3 months of age. Suspected sepsis, presumed sepsis, and “rule-out” sepsis are common diagnoses in neonatal intensive care units (NICUs).


The overall incidence of neonatal sepsis ranges from 1 to 10 cases/1000 live births, with higher incidence observed in lower-birth-weight infants, and in lower-income versus higher-resourced countries. The incidence of EOS has decreased in developed countries with the use of intrapartum Group B Streptococcus (GBS) prophylaxis. In the United States, while the incidence of EOS is less than 1 per 1000 live births, about 35% of extremely low birth weight (ELBW) (<1000 g birth weight) infants in the NICU develop LOS. In low-income countries, the burden of EOS and LOS remains high.


Pathogens vary across geographic regions. GBS and Escherichia coli are the most common causes of EOS in the United States. Listeria monocytogenes is a rare cause of EOS. In the developing world, Klebsiella, E. coli, staphylococci, and streptococci are prevalent. In term infants, LOS is usually caused by GBS, E. coli, or other gram-negative organisms. In low birth weight infants in the NICU, about 50% cases of LOS are caused by coagulase-negative Staphylococcus (CONS) species, about 25% caused by other gram-positive organisms (S. aureus, Enterococcus, or GBS), 20% by gram-negative organisms (E. coli, Klebsiella, Serratia, Pseudomonas, Acinetobacter, Enterobacter) and about 10% by Candida. The common pathogens causing EOS or LOS are listed in Table 41.1. Mortality is highest with gram-negative bacterial and fungal infections.

TABLE 41.1.Microbial Agents Associated With Early- and Late-Onset Neonatal Sepsis

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