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Updated: Jun 10, 2026
A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Multicenter study evaluating performance of the Smart Group B Streptococcus (GBS) assay using an enrichment protocol
Jeanne A Jordan1, Geraldine Hall, Thomas Davis
1Department of Epidemiology and Biostatistics, School of Public Health and Health Services, The George Washington University, 2300 Eye St., NW, 231 Ross Hall, Washington, DC 20037, USA. sphjaj@gwumc.edu
Insights
The Smart GBS LB assay effectively detects Group B Streptococcus (GBS) colonization in pregnant women, offering high sensitivity and specificity. This rapid molecular test aids in preventing infant GBS infections during delivery.
Area of Science:
- Microbiology
- Molecular Diagnostics
- Infectious Disease
Background:
- Group B Streptococcus (GBS) is a primary cause of neonatal infectious morbidity and mortality in the US.
- Current Centers for Disease Control and Prevention (CDC) guidelines recommend antepartum screening for GBS colonization between 35-37 weeks gestation.
- Intrapartum antibiotic prophylaxis is recommended for colonized pregnant individuals to prevent neonatal transmission.
Purpose of the Study:
- To evaluate the performance characteristics of the Smart GBS LB assay for detecting GBS colonization.
- To compare the Smart GBS LB assay against standard broth enrichment culture and a predicate nucleic acid amplification test (NAAT).
- To assess the assay's utility in antepartum screening of combined vaginal/rectal swabs.
Main Methods:
- Prospective, three-site investigational study conducted from May to August 2006.
- Combined vaginal/rectal swabs were collected from pregnant subjects.
- Specimens were tested using broth enrichment culture, the Smart GBS LB assay, and the BD GeneOhm StrepB assay.
Main Results:
- The Smart GBS LB assay demonstrated high performance compared to enrichment culture: 98.6% sensitivity, 90.4% specificity, 77.1% positive predictive value, and 99.5% negative predictive value.
- The assay showed performance equivalent or superior to the predicate device.
- 310 subjects were enrolled, with 306 results included in the analysis.
Conclusions:
- The Smart GBS LB assay is a reliable method for detecting GBS colonization in pregnant women.
- The assay's performance supports its use as an alternative to traditional culture methods for antepartum GBS screening.
- Careful sample handling during nucleic acid amplification testing is crucial to prevent contamination.
Abstract:
Group B streptococcus (GBS) remains the leading cause of infectious morbidity and mortality in infants born in the United States, especially among black infants. Because a newborn can acquire GBS during and after delivery, the Centers for Disease Control and Prevention (CDC) recommends that pregnant women be screened for rectovaginal GBS colonization during the antepartum period between weeks 35 and 37 of gestation and, if they are colonized, that intrapartum antibiotic prophylaxis be administered. A prospective investigational study was undertaken from 2 May 2006 to 14 August 2006 at three sites to establish the performance characteristics of the Smart GBS LB assay on the SmartCycler II system for detecting GBS colonization in subjects in the antepartum period from combined vaginal/rectal swab-based specimens after broth enrichment. Results were compared to broth enrichment culture and to the predicate device, the BD GeneOhm StrepB direct assay. The collected specimens were randomized for swab testing order. Each swab sample was processed simultaneously by culture, Smart GBS LB assay, and the BD GeneOhm StrepB assay. A total of 310 subjects were enrolled, with 306 subject results included in the study. Compared to enrichment culture, the Smart GBS LB assay demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 98.6%, 90.4%, 77.1%, and 99.5%, respectively. The Smart GBS LB assay demonstrated substantially equivalent or better performance than culture or the predicate device. Screening of broth enrichment fluids by nucleic acid amplification testing requires careful handling during sample processing to avoid possible contamination.
