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The adoption of Centers for Disease Control and Prevention guidelines for intrapartum antibiotic prophylaxis to reduce vertical transmission of Group B streptococcus (GBS) resulted in an 80% decrease in neonatal GBS sepsis.
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Nonetheless, GBS and Escherichia coli remain the most common causes of early-onset sepsis in neonates.
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Coagulase-negative staphylococci are now the most common cause of late-onset neonatal sepsis, particularly in low birth weight infants.
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Among commonly used biomarkers, limited
Neonatal Infectious Diseases: Evaluation of Neonatal Sepsis
Section snippets
Key points
Epidemiology of neonatal sepsis
Neonatal sepsis remains a feared and serious complication, especially among very low birth weight (VLBW) preterm infants. Neonatal sepsis is divided into early-onset and late-onset sepsis, based on timing of infection and presumed mode of transmission. Early-onset sepsis (EOS) is defined by onset in the first week of life, with some studies limiting EOS to infections occurring in the first 72 hours that are caused by maternal intrapartum transmission of invasive organisms. Late-onset sepsis
Development of the immune system and increased risk of neonates to infections
The development of the immune system entails a number of changes that occur during the first years of life. Neonates, especially preterm infants, are relatively immunocompromised because of immaturity of the immune system, as well as decreased placental passage of maternal antibodies. Here we highlight some of the components of the neonatal immune system that are immature and contribute to increased susceptibility to serious bacterial, fungal, and viral infections.
Etiologic agents in neonatal sepsis
The etiologic agents associated with neonatal sepsis in the United States have changed over time.5 In this section, we review current data on organisms associated with early-onset and late-onset neonatal sepsis (Table 2).
Group B-streptococcus
Despite widespread use of IAP to prevent vertical transmission of invasive GBS disease, missed opportunities for prevention exist and GBS remains the most common organism associated with EOS in the United States. According to the Centers for Disease Control and Prevention (CDC), rates of early-onset invasive GBS disease have declined by 80% since the CDC prevention guidelines were first published.9 GBS are gram-positive encapsulated bacteria for which 10 different serotypes have been
LOS
The increased survival of preterm low birth weight infants, particularly those who are VLBW, with need for prolonged hospitalization and use of invasive procedures and devices, especially long-term intravascular catheters, results in ongoing risk of infection. LOS is largely caused by organisms acquired from the environment after birth. The following section reviews the most common organisms associated with LOS (see Table 2).
Clinical manifestations
Both EOS and LOS have nonspecific clinical manifestations (Table 3). The importance of a lumbar puncture in neonates with suspected sepsis and without specific CNS clinical manifestations is underscored by studies showing growth of CSF cultures despite negative blood cultures, especially in VLBW infants.72
Diagnostic methods
Early diagnosis of neonatal sepsis is challenging because clinical characteristics are nonspecific and difficult to differentiate from those of noninfectious etiologies, and because the repertoire of ancillary laboratory tests is limited and not always reliable. Blood culture remains the gold standard for diagnosis of neonatal sepsis, but the rate of positivity is low, influenced by factors such as intrapartum antimicrobial administration and limitations in blood volume per culture that can be
Prevention and Infection Control Practices
Prevention of neonatal sepsis is the goal, through implementation of what is known and development of new prevention strategies. Maternal prenatal care continues to be important for prevention of EO GBS sepsis with identification of maternal carriage of GBS through universal screening for all pregnant women. Early recognition of chorioamnionitis, with appropriate antimicrobial therapy for the mother, decreases maternal fetal transmission. The recent CDC GBS prevention guidelines emphasize the
Summary
Neonatal sepsis continues to be a significant cause of morbidity and mortality in term and preterm infants. Although GBS and E coli are the most common pathogens associated with EOS, and CoNS are the most frequently isolated agents in newborns with LOS, other organisms, as well as multidrug-resistant pathogens, need to be considered. Development of accurate novel early diagnostic markers will allow clinicians to better assess the risk of infection and need for antibiotic therapy. Adherence to
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