GBS (Group B streptococcus)

Sensitive and fast detection of GBS during pregnancy and at the time of delivery

Why choose our test?

The GenomEra® GBS Assay Kit is a qualitative molecular assay indicated for the rapid identification of antepartum and intrapartum colonization of Group B Streptococcus (GBS, Streptococcus agalactiae) in pregnant women. The assay simplifies and speeds up GBS testing by providing reliable results from vaginal-rectal swab samples in less than one hour.

GBS, a gram-positive bacterium, is the most significant cause of early onset sepsis and it is associated with significant morbidity and mortality among infants1. GBS may also cause invasive infections in pregnant or post-partum women2and older adults3, and is commonly found in the gastrointestinal, genital, and urinary tract of healthy adults. Up to 30% of pregnant women are colonized with GBS in the vagina or rectum4.

GBS is the leading cause of life-threatening infections in newborns, and therefore a rapid and sensitive detection of neonatal infections and the initiation of appropriate treatment is needed to minimize morbidity and mortality. For prenatal screening, the accuracy and timing of testing is important to prevent unnecessary use of intrapartum antibiotic prophylaxis (IAP), which could disturb the normal flora and contribute to the development of resistant strains. PCR has proven to be a useful diagnostic tool due to its unmatched sensitivity and specificity as well as its rapid turnaround time.

Key facts

  • High-performance detection of Group B Streptococcus (GBS, Streptococcus agalactiae) from vaginal-rectal swab samples in less than one hour
  • Selective broth enrichment followed by PCR provides the highest level of sensitivity for GBS detection
  • Easy-to-use, automated GenomEra molecular diagnostic system with a low inhibition rate and a minimal risk of contamination

Assay principle

GenomEra GBS Assay Kit is designed for the detection of GBS in intrapartum screening utilizing the GenomEra CDX System5,6. The kit is suitable for vaginal-rectal swab specimens in Copan eSwab™ transport medium collected from pregnant intrapartum or antepartum women, and for enrichment broth cultures of vaginal-rectal swab specimens collected from antepartum women. Cultures are performed by incubating the swab specimens in selective enrichment broth medium preferably for 4 h or 18–24 h or until bacterial growth is detected. Selective broth enrichment followed by PCR has been shown to provide the highest level of sensitivity for GBS detection5.

The GenomEra GBS assay is based on end-point PCR that detects a specific region of the S. agalactiae genome, ensuring comprehensive coverage of GBS strains. The assay contains a very simple sample preparation and yields reliable results in less than one hour. Pre-loaded and sealed test chips allow for easy testing, contamination-free environment, and safe waste disposal. The automated GenomEra platform allows for rapid and effortless GBS testing.

Clinical performance

The clinical performance of the GenomEra GBS Assay Kit was evaluated for vaginal swab enrichment cultures at two hospital laboratories, one in Finland (n = 282) and one in Israel (n = 90) (Table 1). The reference methods used in the evaluation were blood culture or culture on a chromogenic agar plate and analysis by MALDI-TOF, or a Group B Streptococci antigen test. Additionally the GenomEra GBS Assay Kit was evaluated for vaginal-rectal swab samples in Denmark at two sites (n= 361)  and in Finland (n=267) and in Lebanon (n=177)  at one site. The reference methods used in the evaluation were blood culture or culture on a chromogenic agar plate and analysis by latex agglutination assay, or a MALDI-TOF system.

Table 1. The GenomEra® GBS Assay Kit proved to be highly sensitive and specific in clinical use. PPV, positive predictive value; NPV, negative predictive value.

  Sample size (n) Sensitivity (%, n) Specificity (%, n) PPV (%) NPV (%)
Overnight enrichment broth cultures 396 98.0 (97/99) 98.3 (288/293) 95.1 99.3
Four-hour enrichment broth cultures 114 96.4 (27/28) 96.5 (83/86) 90.0 98.8
Vaginal-rectal swab 805 83.1 (162/195) 96.6 (564/584) 89.0 94.5


The GenomEra GBS Assay Kit has shown good clinical performance in a clinical study (Table 2) 5.

Table 2. GenomEra® GBS Assay Kit yielded excellent performance values in a clinical study5.

  Sample size (n) Sensitivity (%) Specificity (%) PPV (%) NPV (%)
Culture as a reference 358 91.9 98.1 94.7 97.0
Combined standard as reference* 366 92.2 99.6 98.9 97.0

* The combined reference standard was established by defining true positives as either culture-positive samples or culture-negative samples where GBS PCR assays were positive

Ordering information

To place an order, please contact your local distributor.

Product name Product code
GenomEra GBS Assay Kit
20 tests CDX-60-01-20
40 tests CDX-60-01-40
GenomEra CDX System CDX-10-020

The GenomEra GBS Assay Kit has received the European CE marking for In Vitro Diagnostic (IVD) medical devices according to the requirements of EU Directive 98/79/EC (IVDD) and is available in European markets. In other markets, please contact your local distributor for availability. The product is manufactured by Uniogen, Finland.


  1. Heath P, Schuchat A. Perinatal group B streptococcal disease. Best Pract Res Clin Obstet Gynecol 2007;21:411–24.
  2. Deutscher M, Lewis M, Zell ER, Taylor TH Jr, Van Beneden C, Schrag S; Active Bacterial Core Surveillance Team. Incidence and severity of invasive Streptococcus pneumoniae, group A Streptococcus, and group B Streptococcus infections among pregnant and postpartum women. Clin Infect Dis 2011;53:114–23.
  3. Farley M. Group B streptococcal disease in nonpregnant adults. Clin Infect Dis 2001;33:556–61.
  4. Rodriguez-Granger J, Alvargonzalez JC, Berardi A, Berner R, Kunze M, Hufnagel M, Melin P, Decheva A, Orefici G, Poyart C, Telford J, Efstratiou A, Killian M, Krizova P, Baldassarri L, Spellerberg B, Puertas A, Rosa-Fraile M. Prevention of group B streptococcal neonatal disease revisited. The DEVANI European project. Eur J Clin Microbiol Infect Dis 2012;31:2097–104.
  5. Nielsen SY, Møller JK, Khalil RM. A comparison of GenomEra® GBS PCR and GeneXpert® GBS PCR assays with culture of GBS performed with and without broth pre-enrichment. Eur J Clin Microbiol Infect Dis 2020; 39 (10);1945-1950.
  6. Hartvigsen CM, Nielsen SY, Møller JK, Khalil MR. Reduction of intrapartum antibiotic prophylaxis by combining risk factor assessment with a rapid bedside intrapartum polymerase chain reaction testing for group B streptococci. Eur J Obstet Gynecol 2022; 272; 173-176.

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