Polymerase spiral
reaction assay for diagnosis of Streptococcus agalactiae in vaginal swabs of 35
to 37 week pregnant women
Anh Nguyen Thi Truc, Uyen Nguyen Thi Phuong, Van Le Thi Thanh, Diem Tran Hong and
Hieu Vu_Quang
Res. J. Biotech.; Vol. 21(1); 80-86;
doi: https://doi.org/10.25303/211rjbt080086; (2026)
Abstract
Streptococcus agalactiae, commonly referred to as Group B Streptococcus (GBS), was
the most common neonatal infection. Antenatal GBS screening is recommended to reduce
the risk of GBS transmission from mother to newborn. GBS is diagnosed using traditional
culture methods and qPCR; however, in some cases, these methods cannot be applied
for diagnosis. Therefore, we studied the potential application of polymerase spiral
reaction (PSR) in direct GBS diagnosis from rectovaginal swab samples from 35 to
37 week pregnant women. Results showed that PSR reactions can be performed at 62°C
for 50 minutes, with a detection limit down to 25 bacteria/reaction.
For clinical samples, our design could detect GBS with sensitivity, specificity,
diagnostic accuracy and a Kappa index of 84%, 90%, 87% and 0.74, 88%, 83%, 85% and
0.68 when compared to qPCR and microbiological culture methods respectively. The
study needs to be expanded to improve the sensitivity and accuracy of the reaction,
but it shows potential for application in GBS diagnosis in pregnant women.
