Group B streptococcus and pregnancy : towards an optimal prevention strategy for neonatal Group B Streptococcal Disease

Abstract

Group B Streptococcus (GBS, Streptococcus agalactiae) has been recognized as an important cause of perinatal morbidity and mortality. The frequency of GBS colonization ranges from 10% to 35% in women of reproductive age. GBS colonization can be transient, intermittent or persistent. Vertical transmission of GBS from mother to child occurs during labor. Studies on vertical GBS transmission in colonized mothers during labor report incidences of colonization of the infant between 16 and 69%. Early-onset group B streptococcal disease (GBS-EOD) occurs in approximately 1% of newborns who are colonized with GBS. Established risk factors for acquiring GBS-EOD are prolonged rupture of membranes, preterm labor, intrapartum fever, GBS bacteriuria during pregnancy or a previous child with GBS-EOD. Intrapartum antibiotic prophylaxis (IAP) given to women at risk of transmitting GBS to their baby may prevent GBS-EOD. Identification of mothers at risk may be performed by screening (taking a culture during pregnancy to detect maternal colonization) and/ or by identifying pregnancies with one or more of the established risk factors for GBS-EOD. Since the overall effect of the Dutch guideline on the incidence of GBS-EOD is disappointing, adaptation of the Dutch guidelines should be reconsidered. The aim of this thesis is to contribute to the information needed for the establishment of an optimal prevention strategy for GBS-EOD. In this thesis, studies on prevalence of GBS carriage, risk factors for GBS-sepsis in relation to GBS carriage, timing of GBS cultures, association of GBS carriage and preterm labor and resistance of GBS for antibiotics are combined.