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Updated: Feb 19, 2026
A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Intrapartum group B Streptococcus screening in the labor ward by Xpert® GBS real-time PCR
C Plainvert1,2,3,4, F El Alaoui5, A Tazi6,7,8,9
1AP-HP, Service de Bactériologie et Centre National de Référence des Streptocoques, Hôpitaux Universitaires Paris Centre site Cochin, Paris, France. celine.plainvert@aphp.fr.
Insights
Point-of-care Group B Streptococcus (GBS) PCR testing shows promise for intrapartum detection. However, training is crucial for accurate results, potentially reducing unnecessary antibiotic use in pregnant women.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Obstetrics
Background:
- Group B Streptococcus (GBS) is a major cause of neonatal infections.
- Intrapartum antibiotic prophylaxis (IAP) is vital for preventing early-onset neonatal GBS infection.
Purpose of the Study:
- To compare the performance of Xpert® GBS PCR point-of-care testing with standard culture for intrapartum GBS detection.
- To evaluate the utility of intrapartum GBS detection in guiding IAP and preventing unnecessary antibiotic administration.
Main Methods:
- Prospective cohort study of 565 pregnant women with antenatal GBS-positive screening.
- Vaginal swabs collected at delivery for both Xpert® GBS PCR and standard GBS culture.
- Comparison of PCR and culture results, including analysis of PCR success rates and discordant results.
Main Results:
- Xpert® GBS PCR achieved 91.3% valid results after repeat testing.
- PCR detected 78.0% of GBS-positive cultures, with cycle thresholds correlating to bacterial load.
- A significant proportion of women (21.5%) tested PCR-positive despite negative cultures, with many having received IAP prior to sampling.
- Only 59.3% of women with antenatal GBS positivity remained positive at delivery, indicating potential for unnecessary IAP in 40%.
Conclusions:
- Xpert® GBS PCR is a potentially valuable tool for intrapartum GBS detection, offering an alternative to culture-based methods.
- Laboratory staff training is essential to achieve the required performance standards for point-of-care testing.
- Intrapartum testing may help optimize IAP strategies, reducing unnecessary antibiotic exposure in pregnant women.
Abstract:
Group B Streptococcus (GBS) is the leading cause of neonatal infections in industrialized countries. Intrapartum antibiotic prophylaxis (IAP) given to colonized parturients is a key step for the prevention of neonatal early-onset infection. We compared the performances of Xpert® GBS polymerase chain reaction (PCR) (Cepheid, Sunnyvale, CA, USA) as a point-of-care system in labor wards to standard culture for intrapartum GBS detection. Pregnant women with a GBS-positive antenatal screening were prospectively included. A vaginal double swab was collected at the time of delivery for point-of-care Xpert® GBS PCR and GBS culture. A total of 565 pregnant women were included. Valid Xpert® GBS results were obtained for 488 (86.4%) women on the first attempt. Repeat testing improved the PCR success to 516 (91.3%) women. Among the 305 women positive for GBS by culture at delivery, only 238 (78.0%) were positive by Xpert® GBS PCR, cycle thresholds being correlated to culture quantification. Among 260 women negative for GBS culture, 56 (21.5%) were positive by Xpert® GBS PCR, including 50 where IAP was initiated before vaginal sampling. Overall, among the 565 women with GBS antenatal positive culture, only 335 (59.3%) were still positive at delivery whatever the technique used, resulting in unnecessary IAP for 40% of them. This large cohort study comparing intrapartum to antepartum GBS detection provides evidence that (i) Xpert® GBS PCR might be a valuable solution for intrapartum GBS detection compared to culture-based strategies and (ii) laboratory training of non-specialized staff is mandatory to reach the performances required for point-of-care tests.
