Geographic Variation in the Urinary Microbiota of Patients with Urolithiasis

Background: Geographic variation may influence the urinary microbiota of patients with urolithiasis. This study compared urinary microbial profiles between Taiwan and Korea patients. Materials and Methods: This cross-national comparative study included 72 patients with clinically confirmed urolithiasis, comprising 31 patients from Taiwan and 41 from South Korea. Bladder urine samples were collected by urethral catheterization before surgery and prophylactic antibiotic administration. Full-length 16S rRNA genes were amplified using the 27F and 1492R primers and sequenced using a third-generation long-read sequencing platform. Sequence denoising and amplicon sequence variant inference were performed using DADA2, followed by taxonomic annotation and phylogenetic analysis in QIIME2. Alpha diversity, beta diversity, and differential taxonomic abundance were compared between the two groups. Results: No significant differences were observed in alpha diversity indices, including microbial richness, diversity, evenness, and phylogenetic diversity. However, beta diversity analyses demonstrated significant differences in overall urinary microbial community composition between the Taiwan and Korea groups, as shown by ANOSIM, MRPP, and perMANOVA. Differential abundance analysis identified enrichment of Proteobacteria, Shigella flexneri , and several related taxa in the Taiwan group, whereas Gardnerella swidsinskii , Prevotellaceae, and Veillonella were enriched in the Korea group. At the species level, G. swidsinskii showed significantly greater relative abundance in the Korea cohort. Conclusion: Taiwanese and Korean patients with urolithiasis exhibited distinct urinary microbial profiles despite similar alpha diversity. These findings suggest that geographic, dietary, and microbial factors may contribute to population-specific patterns of urinary stone disease.