GBS carriage in pregnant women - Part 2 of the Netherlands Observational study on Gbs disease, Bacterial virulence and protective Serology - (NO GBS)

Streptococcus agalactiae (Group B Streptococcus, GBS) and E. coli are the
leading cause of neonatal sepsis and meningitis. One in five pregnant women
carries GBS asymptomatically. Transmission of GBS bacteria to the neonate can
result in invasive disease, with a case fatality rate of 7%.
Dutch GBS prevention guidelines recommend intrapartum antibiotic prophylaxis
for pregnant women with risk factors for GBS disease. We have previously shown
that the incidence of neonatal GBS disease is increasing, despite guideline
implementation in 1999. In addition, current guidelines recommend bacterial
prophylaxis and treatment for mothers and their children based on a
risk-calculation. With this strategy a bigger group of children is exposed to
antibiotics than are most likely infected by GBS or E. coli. Another
short-coming in the current guidelines is the focus on early onset disease. The
incidence of late onset disease, i.e. after 7 days of age, has not changed in
the western world in the past decades.
Improved risk assessment, a better understanding of GBS pathophysiology and new
prevention strategies are needed to counter this increase and decrease the
exposure to antibiotics early in life.
Vaccination against GBS during pregnancy might reduce invasive disease in
neonates. GBS vaccines were shown to be safe and immunogenic in pregnant woman.
However, the further evaluation of these vaccines is hampered because of the
high costs of a phase 3 RCT with clinical endpoints. Immune correlates of
protection are needed to evaluate potential effectiveness of these GBS
vaccines.

In this observational cohort study we will determine the prevalence and genetic
profile of colonizing GBS isolates in pregnant women in the Netherlands. We
will collect serum from pregnant women and their newborns to determine specific
IgG concentrations and functionality against vaccine targets that protect
against GBS colonization.

The primary objectives of the NO GBS study part 2 are to determine the
prevalence and genetic profile of colonizing GBS bacteria, and to determine IgG
antibody concentrations and functionality against GBS vaccine targets in Dutch
pregnant woman that are associated with protection against GBS colonization.

The secondary objectives are to determine genetic determinants of GBS for
invasive disease, and to determine immunological parameters associated with
protection against invasive GBS disease. Results from other parts of the NO
GBS study will be added to study these secondary objectives.

We will conduct a prospective, observational, multi-centre cohort study on GBS
carriage in Dutch pregnant women. We will collect the medical correspondence
about the obstetric history and outcome of the current pregnancy, GBS isolates,
and serum from mothers and their newborns.

Patients will be treated according to national and local guidelines. Blood and
recto-vaginal swabs will be collected .The burden is minor and risks are
minimal.

Blood from the newborn will be collected from the umbilical cord from the
placenta after the cord is cut at delivery.