Association between the urogenital microbiome and surgical treatment response in women undergoing midurethral sling operation for mixed urinary incontinence.

BACKGROUND: The urogenital microbiome is associated with urgency and mixed urinary incontinence symptoms and differential treatment responses to pharmacotherapy for urgency urinary incontinence.

OBJECTIVE: This study aimed to describe whether the preoperative urinary and vaginal microbiomes were associated with surgical treatment responses at 12 months after a midurethral sling operation in women with mixed urinary incontinence.

STUDY DESIGN: This cohort study compared the preoperative microbiome compositions of urine and vaginal samples from a subset of women undergoing a midurethral sling operation in the Effects of Surgical Treatment Enhanced With Exercise for Mixed Urinary Incontinence trial (NCT01959347) and compared the microbiota in women who were surgical responders vs surgical nonresponders. Twelve-month objective response was defined as a ≥70% reduction from baseline urinary incontinence episodes on a 3-day diary. Subjective response was defined as a change from baseline in the Urogenital Distress Inventory scores. Bacterial abundance and beta diversity were assessed using 16S ribosomal RNA sequencing. The primary differential abundance analysis described predominant bacterial operational taxonomic units associated with responders vs nonresponders using unadjusted and age-adjusted linear models.

RESULTS: Objective nonresponders (n=28) compared with responders (n=72) were older (58.5±10.7 vs 51.6±10.2 years) and more likely postmenopausal without hormone use (odds ratio, 6.4; 95% confidence interval, 1.8-22.6). Vaginal and urinary microbiota beta diversities were associated with age (P<.05) for both responders and nonresponders. Overall, predominant operational taxonomic units (genera) were Lactobacillus, Gardnerella, Tepidimonas, Escherichia, Streptococcus, and Prevotella. Operational taxonomic units from baseline urine samples were not significantly associated (P threshold=.05) with surgical treatment responses. A greater abundance of baseline vaginal Lactobacillus was associated with an objective response (P=.04) and Prevotella with an objective nonresponse (P=.01). Adjusting for age, only a greater abundance of baseline vaginal Prevotella was associated with an objective nonresponse (P=.01). Moreover, less abundant vaginal operational taxonomic units were associated with objective and subjective responses and persistent urinary incontinence symptoms (P<.05).

CONCLUSION: Women meeting a 70% reduction of urinary incontinence treatment episodes (objective responders) had greater vaginal Lactobacillus at the time of the surgical procedure; however, controlling for age diminished this association. Women not meeting a 70% reduction of urinary incontinence episodes 1 year after a midurethral sling operation had greater vaginal Prevotella at the time of the midurethral sling operation. Further research is needed to determine whether therapy altering the vaginal microbiome may impact surgical treatment responses in women with mixed urinary incontinence.