Intrapartum Molecular Detection of Group B

Antenatal screening for Group B Streptococcus (GBS) does not always reflect intrapartum colonisation status, and rapid molecular point-of-care tests (POCT) have been developed to enable real-time detection during labour. This prospective single-centre study evaluated the performance of six molecular assays (easyNat, FlashDetect, GenDx, GenPad, iPonatic, Revogene) and one antigen-based test (TZcheck) for intrapartum GBS detection under real-world conditions. Vaginal-rectal swabs were collected at admission from 104 women at ≥ 37 weeks of gestation and tested directly without prior enrichment, using conventional intrapartum culture as the reference standard. Diagnostic performance varied substantially across platforms, with positive percent agreement ranging from 0.0% to 80.6%, while negative percent agreement was generally high, except for GenDx. Seven culture-positive samples yielded negative results across all molecular assays, while one sample was consistently positive across multiple molecular platforms despite negative culture. Exploratory observations suggest that differences in lysis procedures may contribute to variability in assay performance, although this could not be formally assessed. These findings highlight the variability of intrapartum molecular POCT under routine conditions and underscore the need for cautious clinical interpretation and local validation prior to implementation.