Can a probiotic taken by mouth reduce group B streptococcus in the vagina during pregnancy?

ISRCTN	ISRCTN47071089
DOI	https://doi.org/10.1186/ISRCTN47071089
Sponsor	Elias University Emergency Hospital, Bucharest, Romania
Funder	Investigator initiated and funded

Submission date: 10/08/2026
Registration date: 16/08/2026
Last edited: 10/08/2026

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Infections and Infestations

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Mihaela Bot
Principal investigator, Scientific, Public

Department of Obstetrics and Gynecology, Elias University Emergency Hospital, 17 Mărăști Blvd.
Bucharest
011461
Romania

Phone	+40723361828
Email	mihaela.bot@umfcd.ro

Dr Andreea Borislavschi
Scientific, Public

Department of Obstetrics and Gynecology, Elias University Emergency Hospital, 17 Mărăști Blvd.
Bucharest
011461
Romania

Phone	0040721910827
Email	andreea.borislavschi@drd.umfcd.ro

Study information

Primary study design	Interventional
Allocation	Non-randomized controlled trial
Masking	Open (masking not used)
Control	Active
Assignment	Parallel
Purpose	Prevention
Scientific title	Targeting vaginal microbiota during pregnancy: oral Lactobacillus crispatus M247 and vaginal Group B streptococcus colonization
Study objectives
Ethics approval(s)	Approved 21/03/2025, Ethics Committee of Elias University Emergency Hospital (17 Mărăști Blvd, Bucharest, 011461, Romania; +40213161600; contact@spitalul-elias.ro), ref: 1835
Health condition(s) or problem(s) studied	Prevention of Group B Streptococcus colonization in pregnancy
Intervention	Participant with a positive vaginal GBS culture at 24-26 weeks of gestation were allocated to one of two parallel groups according to participant preference following standardised counselling; no randomisation and no placebo were used. Intervention group: oral Lactobacillus crispatus M247, 20 billion CFU once daily, for eight weeks, self-administered at home, started after confirmation of vaginal GBS colonisation at 24-26 weeks of gestation. Participant obtained the commercially available product independently from community pharmacies. Control group: standard antenatal care without probiotic supplementation. Both groups followed the same study schedule, with a repeat vaginal GBS culture at 34-36 weeks of gestation. Adherence was assessed by self-report at routine antenatal visits. Laboratory personnel processing the cultures were unaware of group allocation; participants and clinical investigators were not blinded.
Intervention type	Supplement
Primary outcome measure(s)	Persistent vaginal Group B Streptococcus colonisation measured using vaginal culture for Streptococcus agalactiae, collected from the lower third of the vagina, processed by selective enrichment broth followed by subculture on blood and chromogenic agar, with species confirmation by MALDI-TOF mass spectrometry; reported qualitatively as present or absent, at 34-36 weeks of gestation
Key secondary outcome measure(s)	Adherence to oral probiotic supplementation measured using participant self-report of daily probiotic intake, recorded at routine antenatal visits, at 34-36 weeks of gestation Adverse events associated with oral probiotic supplementation measured using participant-reported adverse events recorded at routine antenatal visits, at 34-36 weeks of gestation
Completion date	10/12/2025

Eligibility

Participant type(s)
Age group	Adult
Lower age limit	18 Years
Upper age limit	39 Years
Sex	Female
Target sample size at registration	53
Total final enrolment	53
Key inclusion criteria	1. Pregnant women aged 18 years or older 2. Confirmed viable pregnancy 3. Positive vaginal culture for Group B Streptococcus at 24-26 weeks of gestation 4. Written informed consent
Key exclusion criteria	1. Use of systemic antibiotics 2. Concomitant probiotic use 3. Use of intravaginal antimicrobials 4. Major immunosuppression
Date of first enrolment	24/03/2025
Date of final enrolment	30/09/2025

Locations

Countries of recruitment

Romania

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No

Editorial Notes

10/08/2026: Study’s existence confirmed by the Ethics Committee of Elias University Emergency Hospital, Romania.