Evaluation of the Xpert Xpress GBS test for rapid detection of group B Streptococcus in pregnant women

Abstract

ABSTRACT Group B Streptococcus (GBS) remains the leading cause of serious neonatal infection. Prenatal screening for vaginal and rectal GBS colonization is necessary in late pregnancy. Our objective was to compare the performance of four methods including the Xpert Xpress GBS, standard broth enrichment culture, real-time quantitative PCR (qPCR), and direct culture, for detecting of GBS in rectovaginal specimens. Among 939 pregnant women at 35–37 weeks of gestation recruited in the study, 168 (17.9%) were determined to be GBS-colonized by broth enrichment culture, the gold standard. The sensitivity and specificity of the Xpert Xpress GBS were 94.6% and 95.9%, respectively. The hands-on time and running time of the Xpert Xpress GBS were 1 minute and less than 1 hour, respectively. As a random-access, integrated device, the Xpert Xpress GBS test efficiently and accurately screens rectovaginal swabs for GBS colonization in pregnant women. IMPORTANCE This was the first study evaluating the performance of the Xpert Xpress group B Streptococcus (GBS) test using rectovaginal swabs from Chinese pregnant women. Compared to the other three assays, the Xpert Xpress GBS test demonstrated high sensitivity and specificity when screening 939 pregnant women for GBS in rectovaginal specimens. Additionally, its reduced time to obtain results makes it valuable for the rapid detection of GBS.

Keywords

• group B Streptococcus
• Xpert Xpress GBS
• enrichment culture
• qPCR
• direct culture