Antimicrobial resistance is an escalating global health concern that severely compromises the management of recurrent infections. Recurrent urinary tract infections (UTIs) represent a particularly challenging condition in paediatric patients with structural urinary tract abnormalities and extensive prior antibiotic exposure, where infections are frequently caused by multiantibiotics-resistant and extended-spectrum β-lactamase (ESBL)-producing pathogens.

To address this clinical need, a novel probiotic strain, Lactiplantibacillus sp. LH01, was isolated and characterized from human milk and officially registered. Its clinical potential was evaluated in a pediatric patient with bilateral hydronephrosis, a history of repeated hospitalizations, and recurrent UTIs caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae.

Administration of Lactiplantibacillus ps. LH01 was associated with a marked reduction in UTI recurrence and a sustained clinical improvement. In vitro assays demonstrated an 89% inhibitory activity against ESBL-producing E. coli. Notably, subsequent urinary cultures revealed loss of the ESBL phenotype and restoration of susceptibility to multiple antibiotics that had previously failed, suggesting a potential role in modulating antimicrobial resistance rather than solely suppressing bacterial growth. No adverse events or safety concerns were observed during treatment.

These findings support Lactiplantibacillus sp. LH01 as an innovative and clinically relevant candidate for development as a Live Biotherapeutic Product. This probiotic-based approach may represent a novel adjunctive strategy to reduce antimicrobial resistance and improve outcomes in paediatric patients with recurrent UTIs, particularly in settings where therapeutic options are increasingly limited.