Probiotics as a Promising Strategy for Preventing Urinary Tract Infections: Mechanisms, Efficacy, and Clinical Evidence

Urinary tract infections (UTIs) remain one of the most prevalent bacterial infections globally, with Escherichia coli accounting for most cases and women disproportionately affected due to anatomical and hormonal factors. Recurrent UTIs, which occur in up to 25% of initially affected women, continue to impose a substantial clinical burden despite the widespread use of antibiotics. However, increasing antimicrobial resistance has exposed the limitations of antibiotic-centric management and intensified interest in alternative strategies such as probiotics. Although strains including Lactobacillus crispatus, L. rhamnosus, and L. reuteri are frequently cited as promising candidates, the evidence supporting their efficacy remains heterogeneous and often strain-specific. Proposed mechanisms ranging from competitive exclusion and antimicrobial metabolite production to pH modulation and immune enhancement are biologically plausible, yet their consistency in vivo is not fully established. Clinical studies suggest that probiotics, particularly vaginally administered L. crispatus, may reduce recurrence by restoring urogenital microbial balance; however, variability in colonisation success, dosing regimens, and product standardisation complicates interpretation. Despite these limitations, probiotics offer theoretical advantages over antibiotics, including reduced adverse effects and no contribution to resistance. Future progress will depend on refining strain selection, optimising delivery systems, and strengthening mechanistic and clinical evidence. Overall, probiotics represent a potentially valuable adjunct or alternative for UTI prevention, but their widespread adoption requires more rigorous, standardised, and mechanistically informed evaluation.