GBS colonization and screening in pregnancy: how does it work in Europe?

In Europe, as in North America, GBS infections among infants are associated to high morbidity and mortality even if some differences exist between different European countries.
During the past two decades, major initiatives have been proposed to prevent early onset GBS disease (EOD) and they are still subject of controversy. Several European countries have issued guidelines for the prevention of neonatal GBS diseases, either universal screening-based or risk-based strategy, others have no official guidelines at all. In countries having guidelines, despite considerable efforts and economic resources spent on intrapartum antimicrobial prophylaxis for GBS EOD, cases continue to occur. Among these cases there are a lot of missed opportunities to administer IAP but there are also false negative screening. Therefore in the setting of a maternal GBS-screening program and successful implementation of the strategy, efforts to improve screening for GBS status remain important.
The natural reservoir for GBS is the gastrointestinal tract and is likely the source for vaginal colonization. Among pregnant women, GBS carriage rate in the vaginal and rectal flora ranges from 10% up to 30%. Critical factors that influence the accuracy of detecting GBS maternal colonization are the choice of the body sites sampled, the timing of sampling and the use of selective culture media. The evolution of the different culture options to improve the GBS-screening strategy will be reviewed.
If the optimal time for performing antenatal cultures is between 35 to 37 weeks’ gestation, as GBS carriage is highly variable, the predictive values of GBS antenatal cultures are not always as good predictors of the maternal GBS status at presentation for delivery as expected.
Potential alternative to antenatal GBS-screening culture is the identification of GBS colonization at presentation for delivery. Use of a reliable, sensitive, easy to use rapid test should be cost effective leading to the prevention of more EOGBS cases while reducing the number of unnecessarily IAP. Advances of polymerase chain reaction (PCR) and fluorescence labeling technologies has provided new detection tools for bacterial identification. Therefore, commercialization of rapid detection of GBS through real-time PCR offers the potential for GBS detection among women without prenatal care or those in whom no antenatal culture was collected. However questions of costs and logistics remain unanswered.
Could such rapid intrapartum test replace existing screening strategies or could it be used in conjunction with them?
Colonizing rates and recommended screening procedures existing through Europe will be reviewed.