Microbial community state type stratification and quantitative culture-based assessment of vaginal microbiota in reproductive-age women

The vaginal microbiota plays a crucial role in maintaining female reproductive health; however, subclinical forms of dysbiosis remain insufficiently characterised, particularly regarding the integration of molecular, culture-based, and morphological assessment methods. The purpose of the study was to evaluate the structural, quantitative, and morphological characteristics of the vaginal microbiota in reproductive-age women and to determine the correspondence between molecular microbiome stratification and culture-based morphological findings. Thirty reproductive-age women were selected from 1,000 initially screened participants. Quantitative culture analysis with determination of CFU/mL was performed, along with Gram-stained smear microscopy using digital image documentation and molecular classification of the vaginal microbiota based on 16S ribosomal ribonucleic acid gene sequencing. Microbial concentrations ranged from 10² to 10⁷ CFU/mL. The lactobacillary population showed the greatest variability, with a mean value of (1.6 ± 1.1)×10⁶ CFU/mL. Samples were classified into three microbial community types: type I accounted for 30%, type III for 13.3%, and type IV for 56.7%. Type I was characterised by dominance of Lactobacillus crispatus at (3.8 ± 1.7)×10⁶ CFU/mL and a mean acidity of 3.6 ± 0.3. Type III was associated with Lactobacillus iners at (1.5 ± 0.8)×10⁶ CFU/mL and a moderate increase in acidity to 4.5 ± 0.3. Type IV demonstrated reduced lactobacilli at (4.9 ± 3.2)×10² CFU/mL, increased anaerobic bacteria to 10³-10⁴ CFU/mL, and elevated acidity to 5.6 ± 0.4. The morphological patterns of Gram-stained smears corresponded closely to the molecularly defined microbial types. The integration of quantitative culture analysis with standardised smear microscopy represents an informative tool for stratifying vaginal microbiota states in settings where molecular diagnostics are limited