The effect of the probiotic supplement—ASTARTE™—on the reduction of recurrent urinary tract infection in women aged 18-40 years: protocol for a randomized, double-blind, placebo-controlled study

BACKGROUND: Urinary tract infection (UTI) is one of the most common bacterial infections, contributing to increased antibiotic consumption and high healthcare costs. Clinical studies suggest that probiotics can be effective dietary supplements reducing the risk factors for the development of infections in the intestine and vagina. In this study, we investigate the effect of the orally ingested probiotic combination ASTARTE™ on the composition of bacteria in vaginal and fecal samples, as well as on the occurrence of bacteriologically confirmed UTIs in women of reproductive age. METHODS: CFU) containing Lactobacillus crispatus LBV 88™ (DSM22566), Lacticaseibacillus rhamnosus LBV 96™ (DSM22560), Lactobacillus jensenii LBV 116™ (DSM22567), and Lactobacillus gasseri LBV 150N™ (DSM22583), or placebo, for 6 months. Assessments, including symptom questionnaires, urine culturing and microbiome analysis of vaginal and rectal samples by shotgun sequencing, are conducted at baseline, 2, 4, and 6 months. Compliance is tracked by unused capsule counts. Follow-up visits occur at 8, 10, and 12 months. The primary outcome is the incidence of symptomatic bacteriologically confirmed UTIs during the 6 months intervention period. The secondary objective is the effect of ASTARTE™ on changes in vaginal and gut microbiome. DISCUSSION: This randomized, placebo-controlled, double-blind study investigates the effectiveness of ASTARTE™ in restoring beneficial microbiomes and reducing UTI recurrence. The findings will provide valuable evidence on the effectiveness of a non-antibiotic strategy for the prevention of rUTI as well as insights into the complex interactions between the vaginal and gut microbiome and the risk of rUTI. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05553652. Registered 21 September 2022.