Early Onset Neonatal Sepsis: The Burden of Group B Streptococcal and E. coli Disease Continues

Early onset sepsis (EOS) continues to be a serious and feared complication in neonates. During the 1970s, group B streptococcal (GBS) infections emerged as the leading cause of EOS and meningitis. Prevention strategies, based on intrapartum chemoprophylaxis to reduce vertical transmission of invasive GBS disease in at-risk women, determined a substantial reduction in early onset GBS disease. In 2002, the Centers for Disease Control and Prevention (CDC) recommended universal antenatal screening at 35-37 weeks of pregnancy and intrapartum chemoprophylaxis for women with GBS colonization. The publication of these revised guidelines resulted in an additional reduction in invasive GBS disease.
The epidemiology of neonatal sepsis is continuously evolving. In the past decade, several studies showed increasing rates of early onset Escherichia coli sepsis, particularly among preterm infants. The widespread use of maternal intrapartum antibiotics has raised concerns about the potential for increased risk of non-GBS EOS. Since several studies indicated an increased severity of disease and risk of death for newborns with Gram-negative infections, such a change would be particularly alarming. Therefore, continued surveillance to monitor changes in pathogens, disease severity, and outcome is important to assess optimal prevention and treatment strategies.
In this study, an American group has prospectively investigated the epidemiology of EO infection in a cohort of about 400 000 live births (LBs) born at centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Neonatal Research Network (NRN) during a 4-year period. Infection was defined by positive culture results for blood and cerebrospinal fluid obtained from infants aged ?72 hours plus treatment with antibiotic therapy for =5 days.
Among 396 586 infants (2006–2009), 389 developed EO infection (0.98 cases per 1000 LBs). Infection rates increased with decreasing birth weight. GBS (43%, 0.41 per 1000 LBs) and E. coli (29%, 0.28 per 1000 LBs) were most frequently isolated. Most infants with GBS were term (73%); 81% with E. coli were preterm. Mothers of 67% of infected term and 58% of infected preterm infants were screened for GBS: the results were positive for 25% of these mothers. Only 76% of mothers with GBS colonization received intrapartum chemoprophylaxis. Although 77% of infected infants required intensive care, 20% of term infants were treated in the normal newborn nursery. Last, 16% percent of infected infants died, most commonly with E. coli infection (33%).
In conclusion, this large, prospective surveillance study of almost 400 000 live births documents that in the era of intrapartum chemoprophylaxis, the overall rates of EO infection have declined but reflect a continued burden of disease. GBS remains the most frequent pathogen in term infants, and E. coli the most significant pathogen in preterm infants. In the future, it will be crucial to further improve GBS prevention strategies.
In particular, prevention of E. coli sepsis, especially among preterm infants, remains a challenge.

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