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CME Credit Offered
CME Credit Offered
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Recording available 2/16-5/2
Recording available 2/16-5/2
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AIUM Credit
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Abstract Award
Abstract Award
Foundation Awardee
Foundation Awardee

Poster Session 4

Category: Infectious Diseases

Poster Session 4

(1291) GBS carriage in term-pregnancies: Concordance of detection by prenatal screening, culture, and deep metagenomic sequencing

Thursday, February 12, 2026
3:30 PM - 5:00 PM  
Objective:
Group B Streptococcus (GBS), or Streptococcus agalactiae, is a common component of the vaginal flora but can cause invasive infections in pregnant women, developing fetuses, and neonates. We sought to evaluate concordance between routine prenatal GBS screening and culture-based detection or deep metagenomic sequencing in term-pregnant individuals to assess implications for intrapartum antibiotic prophylaxis decision-making. 

Study Design:
This prospective cohort study enrolled 50 term-pregnant patients and assessed continuity across standard prenatal GBS screen, and culture-based analyses, and deep metagenomic sequencing from vaginal swabs collected at the time of admission for labor. After obtaining consent, a sterile speculum examination was performed for vaginal swab collection. Swabs were used to cultivate GBS, confirming identity by full-length 16S rRNA sequencing, and processed for metagenomic sequencing to detect GBS. Results were compared across all three detection methods and concordance among methods was analyzed to identify GBS colonization. 

Results:
We observed 35.4% (17/48) of individuals had a positive prenatal GBS screen. Culture-based methods identified viable GBS in 34% (16/47) of patient swabs collected upon admission, while metagenomic sequencing detected reads aligning to GBS in 44% (22/50) of individuals. Concordance between prenatal screening and intrapartum culture was observed in 80% (36/45) of individuals with 24.4% (11/45) positive by both and 55.6% (25/45) negative. Result discordance was observed in 20% (9/45), with 8.9% (4/45) positive by prenatal screening but negative by culture, and 11.1% (5/45) negative by prenatal screening but culture positive. Overall, GBS was detected in 64% (32/50) individuals by one or more methods across this dataset (Fig.1). Metagenomic sequencing conferred higher sensitivity, identifying additional cases that were negative by clinical and culture methods.

Conclusion:
These findings suggest that a significant proportion of individuals may be treated inappropriately under the current prenatal screening protocols (Fig. 2).