Protocol for a Diagnostic Accuracy Study of Polymerase Chain Reaction for Detecting Group B iStreptococcus/iColonisation in Early Labour or with Spontaneous Ruptured Membranes

摘要

Background: Group B Streptococcus [GBS] is a bacterium which transiently colonises the genital tract and can be transmitted from mother to baby at birth. Babies colonised with GBS can develop early-onset group B streptococcus disease [EOGBSD] which can lead to extended hospital stay, disability and death. One of the primary methods for determining which women are most likely to be GBS positive at the time of birth is antenatal universal culture-based screening. Recently Polymerase Chain Reaction [PCR] screening has emerged as a point-of-care method for screening women during the intrapartum period. This study will compare the diagnostic accuracy of this new technology and antenatal culture-based screening at 35 to 37 weeks gestational age, with the reference standard of formal culture-based testing in labour. Methods: This prospective observational study will take place in an Australian hospital. Consecutive women with one or more live fetuses, intending to have a vaginal birth will be asked to participate. Planned screening for GBS colonisation using microbiological culture on a self-collected specimen will occur at 35 to 37 completed weeks gestational age as per our usual hospital policy. A PCR GBS test by Xpert GBS (Cepheid) will be performed on admission to labour ward or at the time of rupture of membranes. The reference standard will be a formal GBS culture on a combined lower vaginal and perianal swab. The sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios will be estimated for both antenatal screening and the intrapartum Xpert GBS (Cepheid) point-of-care test and compared to the reference standard. Results: It is expected that the study will be completed by mid to late 2020. Conclusion: This study has the potential to improve the accuracy of GBS screening of pregnant women and therefore health outcomes for mothers and babies. There is also the potential for a cost savings to the health system.