This research letter describes the results of a clinical trial of a novel vaginal synbiotic comprising three L. crispatus strains and a supportive nutrient complex. Results indicated that administration of the synbiotic led to an optimal vaginal microbiome dominated by L. crispatus (CST I) and additionally reduced the abundance of microbes associated with vaginal dysbiosis and the abundance of Candida, the most common source of vaginal yeast infections.

DG is an employee/shareholder at Seed Health. JR is co-founder of LUCA Biologics, a biotechnology company focusing on translating microbiome research into live biotherapeutics drugs for women's health. DH serves as an advisor/consultant at Seed Health.

NCT05659745

This study was funded by Seed Health.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Argus Independent Review Board gave ethical approval for this work.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Selected data produced in the present study are available upon reasonable request to the authors.