A randomized controlled trial of an oral probiotic to reduce antepartum group B Streptococcus colonization and gastrointestinal symptoms


Advocate Aurora UW Medical Group, Aurora Sinai

Advocate Aurora Sinai Midwifery and Wellness Center

Advocate Aurora Research Institute


Background: Probiotics have been suggested as a strategy to reduce antenatal Group B Streptococcus (GBS) colonization. While probiotics are known to improve gastrointestinal symptoms, this has not been studied during pregnancy.

Objectives: To evaluate the efficacy of a probiotic to reduce: 1) Standard of Care (SOC) antenatal GBS colonization and colony counts and 2) gastrointestinal symptoms of pregnancy.

Study: In a double-blind fashion, 109 healthy adult pregnant people were randomized to Florajen3 probiotic or placebo capsules once daily from 28-weeks gestation until labor onset. Baseline vaginal and rectal study swabs for GBS colony forming units (CFU) and microbiome analysis were collected at 28- and 36-weeks gestation. SOC vaginal to rectal GBS swabs were collected on all participants at 36-weeks gestation and determined the need for intrapartum antibiotic prophylaxis. Data collection included solicitation of adverse events, demographic information, Antepartum Gastrointestinal Symptom Assessment (AP-GI-SA) score, yogurt ingestion, sexual activity, and vaginal cleaning practices.

Results: 83 participants completed the study to 36 weeks gestation with no adverse events. Standard of care GBS colonization in the control group was 20.4% and 15.4% in probiotic group participants (-5%; P=.73). The relative risk for positive SOC GBS was 1.33 (95% CI 0.5 to 3.40) times more in control group than in probiotic group (p =0.55). There were no differences in median vaginal (P=0.16) or rectal (P=0.20) GBS CFUs at baseline or at 36 weeks (Vaginal P>0.999; Rectal P=0.56). AP-GI-SA scores were similar at baseline (P=0.19), but significantly decreased in probiotic group participants at 36 weeks (P=0.02). No covariates significantly altered GBS colonization. Significantly more Florajen3 bacteria components in the were recovered in the vaginal/rectal samples of probiotic group participants (32%; P=.04) compared to controls.

Conclusions: The findings of this study provided insufficient evidence for the clinical application of the Florajen3 probiotic intervention to reduce SOC GBS. The prevalence of GBS was lower than expected in the study population and intervention adherence was poor. Probiotic bacteria colonized the genitourinary tract of intervention group participants more than controls and significantly reduced GI symptoms of pregnancy.



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