Probiotics with cranberry extract and vitamin C in women with recurrent urinary tract infections: a randomized controlled trial

Abstract Introduction and Hypothesis : Recurrent urinary tract infections (rUTIs) pose a significant clinical burden in women and contribute to antibiotic use. This study investigates the probiotic properties of Lactiplantibacillus plantarum KABP062 and KABP063, and their efficacy combined with cranberry extract and vitamin C in reducing rUTIs recurrence. Methods : Probiotic functionality and safety were assessed using in vitro and in silico approaches, including antimicrobial activity against uropathogens, gastrointestinal tolerance, enzymatic safety, and genomic screening for bacteriocin and biogenic amine biosynthesis genes. Clinical efficacy of the multi-component formulation was investigated in a double-blind, randomized, placebo-controlled trial involving women with active or recent rUTIs. Participants received daily capsules containing probiotic strains (≥ 10 8 colony forming units, CFUs), cranberry extract (240 mg) and vitamin C (40 mg), or placebo for six months. The primary endpoint was the proportion of women with physician-confirmed recurrences. Secondary outcomes included number of recurrences, antibiotic use (days), vaginal microbiota, and safety. Results : Both L. plantarum strains inhibited multiple uropathogens, including Escherichia coli , and showed gastrointestinal tolerance and a favorable safety profile. A total of 106 women were randomized. After six months, the proportion of participants experiencing at least one UTI did not differ between groups (p = 0.689). However, the active group was associated with a lower number of UTIs compared to control group (p = 0.013). Antibiotic use was also significantly reduced (p = 0.031) in active group vs control, alongside decreases in seven UTI-associated genera in the vaginal microbiota, including Escherichia/Shigella . Adverse events were comparable between groups. Conclusions: The multi-component formula was safe. Although the primary endpoint was not met, the intervention was associated with a lower number of UTIs and reduced antibiotic use, together with potential reductions in the vaginal uropathogen reservoir.