Lactobacillus rhamnosus (West China Hospital)

Recurrent urinary tract infections (UTIs) are common in children and may lead to long-term renal complications, especially in those with vesicoureteral reflux (VUR). Concerns about antibiotic resistance and side effects of prolonged antibiotic use underscore the need for safe, non-antibiotic alternatives. This prospective, self-controlled observational study evaluated a standardized combination of cranberry extract (36 mg proanthocyanidins daily), probiotics (Lactobacillus rhamnosus and Bifidobacterium longum), and vitamin C (250 mg daily) in 39 children aged 3-16 years, including a subgroup with mild-to-moderate VUR. UTI recurrence was compared before and after the 12-month study period. The supplement was administered for 6 months, followed by a 6-month observation period. Microbiological analyses assessed pathogen distribution. Safety and tolerability were monitored. The intervention significantly reduced UTI recurrence, with median episodes decreasing from 3 to 0 in children without VUR (p < 0.001) and from 2 to 0 in children with VUR (p < 0.05). Overall, 27 of 39 participants (69.2%) remained infection-free throughout follow-up, while the remaining participants experienced a reduced number of UTI episodes compared with the pre-supplementation period. Escherichia coli remained the predominant pathogen, while the diversity of other uropathogens changed minimally, indicating fewer infections rather than microbial shifts. The supplement was well tolerated, with mild gastrointestinal symptoms in 5 of 39 participants (12.8%) and no serious adverse events. Subgroup analyses showed consistent benefit across age and sex, with children having higher baseline UTI frequency experiencing the greatest reduction. A multi-component supplement of cranberry, probiotics, and vitamin C effectively reduced recurrent pediatric UTIs, decreased overall infection burden, preserved E. coli as the main pathogen, and was safe and well tolerated, including in children with mild-to-moderate VUR.

This study aimed to evaluate the effects of three probiotic samples-Bifidobacterium longum, Lactobacillus rhamnosus, and Lactobacillus reuteri-on oral pathogens, commensal bacteria, and host oral cells, thereby exploring their potential roles in maintaining microbial balance and promoting host defense.

Probiotic culture supernatants (postbiotic fractions) were tested against oral pathogens (S. mutans, P. gingivalis, F. nucleatum, A. actinomycetemcomitans) and commensal species (S. sanguinis, V. parvula) using optical density assays. Primary human gingival fibroblasts and oral keratinocytes were co-cultured with probiotic preparations to assess cell viability, inflammatory cytokine secretion, and barrier gene expression (FLG, LOR).

B. longum, L. rhamnosus, and L. reuteri samples showed strain- and concentration-dependent inhibition of oral pathogens, while exhibiting minimal effects on beneficial commensals. Appropriate concentrations of probiotic samples preserved fibroblast viability and enhanced keratinocyte survival. Notably, B. longum, L. rhamnosus, and L. reuteri upregulated barrier-associated genes (FLG, LOR) and suppressed IL-6 secretion in inflamed keratinocytes, suggesting immunomodulatory and protective roles.

Probiotic-derived metabolites exert selective antimicrobial and cytoprotective effects in the oral microenvironment. These findings support the dual functions of probiotics in reshaping oral microbial balance and modulating host cell functions and highlight the potential for personalized probiotic strategies in oral disease prevention and management.Further exploration of combined probiotic formulations is warranted to optimize clinical translation.