THE URINARY MICROBIOME AND RECURRENT URINARY TRACT INFECTIONS

Abstract

Objectives. This systematic review aimed to examine the relationship between urinary microbiome diversity, the bacterial composition of the urobiome, and predisposition to recurrent urinary tract infections (rUTIs), while also addressing the gut-bladder axis, interactions between the vaginal and urinary microbiomes, urinary biomarkers of diagnostic value, and microbiome-modulating therapeutic options, based on literature published between 2020 and 2025.

Methods. A systematic search was performed in PubMed and Scopus for publications from 2020 to 2025, with reporting guided by the PRISMA 2020 recommendations. Relevant sources addressing the urinary microbiome and rUTIs were selected, including primary studies, methodological studies, and secondary publications used to contextualize the evidence. Of the 421 records initially identified, 35 sources were included in the final qualitative synthesis.

Results. Women with rUTIs show reduced urinary microbiota diversity, with decreased Lactobacillus species and an increase in potentially pathogenic microorganisms. Uropathogenic Escherichia coli originates from the gut microbiota, where it persists even after treatment, explaining frequent reinfection. The gut-bladder and vagina-bladder axes play an important role, while emerging urinary biomarkers — inflammatory, metabolomic, and lipidomic — offer new diagnostic perspectives. Microbiome-modulating interventions, including fecal microbiota transplantation and probiotics, show promising preliminary results, although so far based on small, heterogeneous studies.

Conclusions. The urinary microbiome plays an active role in rUTI pathogenesis. Reduced microbial diversity, decreased protective lactobacilli, and a gut microbiome poor in butyrate-producing bacteria are associated with an increased risk of recurrence. Microbiome modulation represents a promising therapeutic direction, but requires further validation through large randomized clinical trials.