Urinary and Oral Microbiota Among Men Undergoing Buccal Urethroplasty

Objective: To assess changes in the urinary microbiota after buccal urethroplasty.

Methods: At the University of California San Francisco, we enrolled 9 adult males with urethral strictures undergoing buccal urethroplasty where we collected urine and oral swabs intraoperatively and 3 months postoperatively. 16S rRNA sequencing was used to profile the microbiota.

Results: At baseline, the mouth contains twice the number of unique bacteria (alpha diversity) and the microbial community is significantly distinct compared to the urinary tract. Despite having a buccal mucosa in the urinary tract after urethroplasty, the number of unique bacteria in the urine remained stable. However, the bacterial community composition and structure significantly changed in the urinary tract with the enrichment of Corynebacterium genus at 3 months post-urethroplasty procedure.

Conclusion: In this pilot study, we showed that the alpha diversity in the urinary microbiota did not significantly change despite having a buccal tissue with the capacity to support high bacterial diversity in the urinary tract. To our surprise, the post-urethroplasty urinary microbiota was not a hybrid of baseline oral and urine microbiotas; the changes detected, such as an enrichment of the Corynebacterium genus, were more nuanced yet could profoundly impact surgical outcomes like graft changes and stricture recurrence. Our study not only established the feasibility but also outlined a blueprint for conducting a large-scale study to assess alterations in the urinary microbiome in relation to surgical outcomes.