Persistence of group B Streptococcus vaginal colonization and prevalence of hypervirulent CC-17 clone correlate with the country of birth: a prospective 3-month follow-up cohort study.

To identify factors associated with vaginal colonization and persistence by group B Streptococcus (GBS) and by the hypervirulent neonatal CC-17 clone in late pregnancy and after delivery, a multicentre prospective observational cohort with 3-month follow-up was established in two university hospitals, Paris area, France. Pregnant women were recruited when antenatal screening for GBS vaginal colonization at 34-38 weeks of gestational age was positive. Vaginal samples were analysed by conventional culture methods at antenatal screening, delivery, and 21 and 60 days following delivery.