Analytical performances of a point-of-care loop-mediated isothermal amplification (LAMP) assay to detect Group B Streptococcus in intrapartum pregnant women living in the Democratic Republic of the Congo.

INTRODUCTION: Group B Streptococcus (GBS) is the leading infectious cause of stillbirth, and neonatal morbidity and mortality in sub-Saharan Africa.

METHODS: Vaginal and rectovaginal swab samples were obtained from 274 intrapartum pregnant women in Democratic Republic of the Congo, to be analysed for GBS DNA detection, in parallel by the point-of-care BIOSYNEX AMPLIFLASH® GBS assay (Biosynex SA, Illkirch-Graffenstaden, France), and by reference quantitative PCR (qPCR).

RESULTS: Rectovaginal swabbing, nearly two-fold more positive for GBS than vaginal swabbing alone, showed high prevalence of GBS DNA positivity in 20.1% of eligible intrapartum pregnant women. In the event of significant bacterial carriage (i.e., Ct ≤ 33 by reference qPCR), the AMPLIFLASH® GBS assay with rectovaginal swabbing showed high sensitivity (98.1%) and specificity (100.0%) for GBS DNA detection, with excellent concordance, reliability and accuracy with the reference qPCR, and PPVs and NPVs above 99.0%.

CONCLUSIONS: The study demonstrates high rate of female rectogenital GBS colonization in pregnant Congolese women. The AMPLIFLASH® GBS assay harboured excellent analytical performances in the field, which makes it suitable to be used as point-of-care molecular assay in various hospital and non-hospital settings where rapid diagnosis of GBS is necessary.