Establishment and characterization of a genomic DNA reference material for Group B Streptococcus detection

Group B Streptococcus (GBS) is a leading cause of maternal and neonatal morbidity and mortality. While molecular assays, like nucleic acid amplification tests, are widely used for GBS detection, their accuracy depends on reliable reference standards. We developed a DNA reference material (RM) for GBS from genomic DNA extracted from reference strain ATCC® 13813™. This RM was quantified using droplet digital PCR and exhibited excellent homogeneity and stability. The certified value of the RM, determined through a multi-center collaborative study, was established as $\left(7.53,,\pm ,,0.48\right)\times {10}^3\mathrm{copies}/\mu L$ , where the uncertainty represents the expanded uncertainty. We further applied the RM to assess the analytical performance of three commercial GBS detection kits. None of the kits consistently achieved their claimed limits of detection, a discrepancy that could lead to false-negative results and subsequent misdiagnosis or inappropriate treatment. Clinical validation confirmed the stability and suitability of the GBS DNA RM for clinical application. The establishment of this GBS DNA RM provides a reliable tool for validating commercial diagnostic kits and platforms, thereby improving the accuracy and reliability of GBS nucleic acid detection.