Physiologic-microbiome interactions in the pathogenesis of genitourinary syndrome of menopause among menopausal stages

Background. Menopause is a natural decline in ovarian function, leading to reduced estrogen and progesterone levels. It occurs in three stages: peri-menopause, menopause, and post-menopause. Estrogen plays a crucial role in maintaining the integrity and microbial balance of the vaginal microenvironment. Physiological and microbiome alterations throughout the menopausal stages contribute to the severity of genitourinary syndrome of menopause (GSM), which encompasses a range of symptoms affecting the vagina, bladder, and urethra. The purpose was to investigate the correlation between hormonal fluctuations and vaginal microbiome alterations, as well as their role in the severity of GSM. Materials and methods. This study was conducted from September to December 2024, involving 100 participants: 75 post-menopausal women (aged 45 and older) at various time intervals since their last menstruation, and 25 pre-menopausal women under 40 with regular menstrual cycles. Clinical checkups were performed before sample collection. Hormonal concentrations were measured using the BIOT-YG-I FIA immunoassay analyzer, while microbial isolates were identified using CHROMagar media. Results. A significant difference in estradiol-2 was found: in pre-menopausal women, its level was 179.17 ± 14.21 compared to 64.72 ± 8.53 in peri-menopausal, 28.75 ± 3.49 in menopausal, and 24.50 ± 2.46 in post-menopausal participants. Progesterone level was 0.65 ± 0.06 in pre-menopausal women, 0.370 ± 0.018 in peri-menopausal, in menopausal group — 0.340 ± 0.017, and 0.304 ± 0.017 in post-menopausal. The mean level of follicle-stimulating hormone was lower in pre-menopausal participants — 5.22 ± 0.90 versus 79.00 ± 7.49 in peri-menopause group, 89.72 ± 8.70 in menopause, and 94.17 ± 9.77 in post-menopausal women. Testosterone mean level was higher in pre-menopausal participants — 0.63 ± 0.06 compared to 0.480 ± 0.089 in peri-menopausal participants, 0.480 ± 0.078 in menopausal, and for post-menopause group, it was 0.610 ± 0.091. L.acidophilus proportion isolated from vaginal swab sample was 12.0 % in peri-menopausal participants, 16.0 % in menopausal, 24.0 % in post-menopausal, and 52.0 % in pre-menopause group. In addition, the most isolated bacterial pathogen was E.faecalis, the rates were 64.0 % for peri-menopausal, 56.0 % for menopausal, 60.0 % for post-menopausal and 12.0 % for pre-menopausal participants. In menopause and post-menopause groups, there was significant association between urogenital symptoms and bacterial growth (P > 0.05). Conclusions. Estradiol-2 and progesterone levels progressively decline from peri-menopause to post-menopause, reaching baseline levels. Bacterial diversity is more pronounced in post-menopausal women compared to pre-menopausal participants. Furthermore, in post-menopausal women, a significant correlation was observed between bacterial colonization and the emergence of urogenital symptoms, supporting the link between altered vaginal microbiota and GSM severity.