Study design, materials and methods
This prospective study included 75 women with urinary incontinence (41 SUI, 34 MUI) and 16 age-matched controls. All patients underwent inside-out transobturator MUS implantation. Vaginal swabs were collected preoperatively and 1 month postoperatively, cultured, and isolates were identified by MALDI-TOF MS. Semi-quantitative bacterial load was expressed as lg(CFU/mL). For between-group comparisons, the sample provided approximately 80% power to detect moderate-to-large effect sizes (Cohen’s d ≥ 0.6) at α = 0.05, while smaller effects may have remained undetected, particularly in comparisons involving the control group. For paired (pre- vs post-operative) analyses, the sample size обеспечивал достаточную мощность (>80%) для выявления эффектов умеренной величины (d ≥ 0.5), supporting reliable assessment of within-subject changes.
Results
A total of 75 women with urinary incontinence (mean age 50.8±9.7 years) were included (SUI n=41, MUI n=34). Baseline characteristics did not differ between patients and controls (n=16). Urgency symptoms (OABSS) were significantly higher in the MUI group (p<0.001), while ICIQ-SF scores were comparable.
No significant differences in vaginal microbiota composition, diversity, or bacterial load were observed between SUI and MUI groups, both pre- and postoperatively (p>0.05 for all comparisons). Therefore, microbiological data were analyzed as a single cohort.
Compared to controls, patients demonstrated higher prevalence of Staphylococcus spp. (31.6% vs 3.7%, p=0.006) and lower prevalence of Lactobacillus spp. (13.7% vs 48.1%, p=0.0001) preoperatively.
Postoperatively, the overall microbial diversity remained unchanged; however, significant compositional shifts were observed, including an increase in Lactobacillus spp. (+17.7%, p=0.0001) and a decrease in Staphylococcus spp., Enterococcus spp., and Enterobacterales. Bacterial load significantly decreased (median log CFU 5.33 to 5.00, p=0.037).
Postoperative comparisons with controls showed persistently higher Staphylococcus spp. (p=0.035) and lower Candida spp. (p=0.046).
Significant clinical improvement was observed (ICIQ-SF and OABSS, p<0.001). De novo urgency occurred in 4.8% (SUI), while persistent urgency was noted in 11.7% (MUI).
Interpretation of results
This study demonstrated that women with urinary incontinence exhibit alterations in vaginal microbiota compared to controls, characterized by higher prevalence of Staphylococcus spp. and reduced Lactobacillus spp., reflecting non-specific dysbiosis associated with persistent urine leakage rather than infection.
No significant differences in microbiological profile, diversity, or bacterial load were found between SUI and MUI groups, suggesting that urgency symptoms are not directly associated with vaginal microbiota composition.
Following surgery, despite significant clinical improvement, shifts in microbial composition were observed, including increased Lactobacillus spp. and reduced bacterial load, while overall diversity remained unchanged. These findings indicate structural rather than dysbiotic changes.
Postoperative comparisons with controls revealed only minor differences, highlighting interindividual variability in microbiota recovery.
Limitations include small control group, use of culture-based methods, and short follow-up. Further studies using molecular techniques are warranted.