Neonatal Sepsis of Vertical Transmission: An Epidemiological Study from the “Grupo de Hospitales Castrillo” Spanish Neonatal Network

Introduction: Neonatal sepsis of vertical transmission (early-onset sepsis) occurs as a result of colonization of the fetus before or during labor by microorganisms from the maternal genital tract. Group B streptococcal (GBS) infection is the most frequent cause of vertical sepsis and a leading cause of neonatal mortality. In Spain, national guidelines for the prevention of perinatal GBS infection were issued in 1998. The objective of the present study was to assess the epidemiology of early-onset vertical sepsis (EOVS) in our country (Spain).

Materials and Methods: Since 1996, the neonatal units of 43 acute-care hospitals in Spain (“Grupo de Hospitales Castrillo” Neonatal Network) carries out a prospective surveillance of the epidemiology of vertical neonatal sepsis. We analyzed the database searching for demographic, clinical, and microbiological characteristics of all EOVS reported by the network in a 20-year period 1996 to 2017.

Results: Out of 2,091,663 live births in the study period, 2,431 cases of EOVS were retrieved. The incidence rate of EOVS declined by 55% over the study years, from 2.4/1,000 live birth in 1996 to 1 to 1.2/1,000 in the period 2002 to 2017 (p < 0.0001). This incidence was significantly higher in the group of very-low-birth-weight (VLBW) neonates than in those weighing >1,500 g. GBS (767 cases) and Escherichia coli (716 cases) were the most prevalent isolated organisms. Some 74.2% of GBS sepsis occurred in term infants, while, in contrast, some 65% of E. coli sepsis occurred in preterm infants. The incidence rate of GBS vertical sepsis declined significantly by 73.6% over the study years, from 1.25/1,000 live births in 1996 to 0.3/1,000 as of 2002 (p < 0.001). There were annual fluctuations in the incidence of E. coli sepsis with a nonsignificant increase in very-low-birth-weight (VLBW) infants (p < 0.1). The mortality rate of vertical sepsis ranged between 8 and 18% in the study period and was significantly higher in preterm than in term infants (24.7 vs. 3%) and in E. coli than in GBS vertical sepsis (18 vs. 7.4%). The mortality per 1,000 live birth decreased from 0.20 (1996) to 0.11 (2017).

Conclusion: In Spain, a substantial decline in the incidence of EOVS occurred during the past 20 years, with a significant reduction in the incidence of GBS sepsis following the implementation and clinical impact of routine, widespread antimicrobial intrapartum prophylaxis against GBS. Fluctuations in the incidence rates of E. coli infection suggest the need for continuing epidemiological surveillance.

Keywords: early-onset sepsis; vertical sepsis; group B streptococcal

Conflict of Interest: None declared.