Implementation of guidelines for group B streptococcal (GBS) prepartum screening (PS) rarely has been prospectively evaluated. To assess PS at 35-37 weeks of gestation and compare its predictive value to that of an intrapartum screening (IS) within 7 days of delivery, a surveillance cohort study was conducted at a tertiary care center in Freiburg, Germany, during 2011-2012. Study participants included 937 pregnant women who had intrapartum cultures taken for vaginal and rectal GBS colonization. Colonization status was compared to PS, and intrapartum antibiotic prophylaxis (IAP) rates calculated. The neonates were tested for GBS transmission via cultures from their throats and external ear canals. While 67.5% (633/937) of study participants had a PS, only 22.7% (144/633) underwent a fully guideline-compatible PS. However, maternal GBS colonization rates were similar when comparing PS (18.5% [117/633]) versus IS (17.0% [133/784]). The positive predictive value of a positive PS result for GBS positivity at delivery was 77.2 %. Women with a positive PS received IAP in 89.3% of cases (75/84). The capsular serotype distribution pattern of colonizing GBS strains has not changed in comparison to our 2003-2004 study--one with a similar study design.
Conclusions: Improved strategies for adoption of prepartum GBS screening are needed.
What is known: • The prediction of prepartum GBS screening for intrapartum colonization status has not been well studied. • Longitudinal studies of GBS screening are needed for screening program evaluations and vaccine development. What is New: • The rate of GBS screening has improved over 10 years, and intrapartum GBS colonization prediction was accurate. • Serotype distribution was stable and suggests the potential long-term efficacy of GBS vaccines.