The Effect of Oral Supplementation with a Multi-Strain Probiotic Preparation on Group B Streptococcus (GBS) Carriage in Pregnant Women-A Pilot Study.

2026-01-30
Journal of clinical medicine 15(3)

PubMed: 41682795
DOI: 10.3390/jcm15031113

Study Design

Type: Clinical Trial
Sample size: n = 46
Population: 10 pregnant women (18-40 years) with singleton pregnancies and a positive vaginal and/or rectal GBS swab, without pre-gestational or gestational diabetes and without antibiotic use in the 4 weeks before enrolment
Methods: Prospective, single-centre, open-label pilot intervention study; participants received OMNi-BiOTiC® FLORA plus orally at 2 × 2 g/day from the 15th to the 34th gestational week; microbiological swabs were obtained at qualification (12-15 weeks), mid-pregnancy (22-25 weeks), and late pregnancy (34-35 weeks)

Background/Objectives: Maternal rectovaginal carriage of Group B Streptococcus (GBS, Streptococcus agalactiae) is a major risk factor for vertical transmission and early-onset neonatal infection. Intrapartum antibiotic prophylaxis reduces early-onset disease but does not address antenatal carriage and may affect the maternal-neonatal microbiota. Microbiota-directed interventions, including probiotics, are being explored as complementary strategies. Methods: This prospective, single-centre, open-label pilot intervention study included 10 pregnant women (18-40 years) with singleton pregnancies and a positive vaginal and/or rectal GBS swab, without pre-gestational or gestational diabetes and without antibiotic use in the 4 weeks before enrolment. Participants received OMNi-BiOTiC^® FLORA plus (multi-strain lactic acid bacteria, including Lactobacillus crispatus) orally at 2 × 2 g/day from the 15th to the 34th gestational week. Microbiological swabs were obtained at qualification (12-15 weeks), mid-pregnancy (22-25 weeks), and late pregnancy (34-35 weeks). Outcomes were described descriptively. Results: Among 56 screened pregnant women, 10 were GBS-positive (17.9%) and enrolled. All participants were GBS-positive at baseline. At 22-25 weeks, 5/10 (50%) had a negative GBS result. At 34-35 weeks, 9/10 (90%) were GBS-negative, while 1/10 (10%) remained colonised. Time to first negative result ranged from 7.6 to 20.2 weeks from supplementation start (median 8.6 weeks). No recurrences (negative-to-positive transitions) were observed between the second and third sampling points. No adverse events related to supplementation were reported. In contrast, among the 46 women who were GBS-negative at screening and did not receive probiotic supplementation, 14 (30.4%) were found to be GBS-positive at routine screening performed at 35-37 weeks of gestation. Conclusions: In this pilot single-arm study, oral supplementation with a multi-strain probiotic preparation during pregnancy was associated with a time-dependent reduction in rectovaginal GBS carriage and was well tolerated. These preliminary findings support the feasibility of larger randomised controlled trials incorporating microbiome profiling and neonatal outcomes.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Lactobacillus crispatus LBV88	—	Reduced Group B Streptococcus Colonization	Beneficial	Moderate	View source At 22-25 weeks, 5/10 (50%) had a negative GBS result. At 34-35 weeks, 9/10 (90%) were GBS-negative, while 1/10 (10%) remained colonised.
Lactobacillus crispatus LBV88	—	Well Tolerated	Beneficial	Small	View source No adverse events related to supplementation were reported.
Lactobacillus rhamnosus LBV96	—	Reduced Group B Streptococcus Colonization	Beneficial	Moderate	View source At 22-25 weeks, 5/10 (50%) had a negative GBS result. At 34-35 weeks, 9/10 (90%) were GBS-negative, while 1/10 (10%) remained colonised.