Vaginal microbes in sexual health and disease

Increasing evidence suggests that the composition of the vaginal microbiota (VM) affects a woman’s sexual and reproductive wellbeing. Lactobacillus-dominated VM is associated with vaginal health (pH<4.5, no inflammation), whereas a VM consisting of diverse anaerobes (i.e. vaginal dysbiosis) increases a woman’s susceptibility to sexually transmitted infections (STI) and adverse pregnancy outcomes. This thesis covers topics relating to biological and (modifiable) behavioral factors that may associate with VM composition and also explores the use of molecular tools to assess the epidemiology of common vaginal conditions such as bacterial vaginosis and trichomoniasis.
Embedded in a larger Amsterdam population-based study, we found that women of African descent were more likely to have vaginal dysbiosis than Dutch-Caucasian women, independent of modifiable behavioral factors. In a separate longitudinal study among Dutch healthy women we found that vaginal douching increased the odds for having vaginal dysbiosis, but not statistically significantly so. In women notified for Chlamydia trachomatis infection by a sex partner, we found that women with vaginal dysbiosis were four times more likely to test positive for infection than women with Lactobacillus crispatus-dominated VM. Lactobacillus crispatus could potentially be used as a probiotic to restore vaginal dysbiosis and our comparative genomic analysis of 30 human isolates revealed bacterial genes relating to this species’ adaptation to the vaginal niche. Molecular tools are sensitive methods to diagnose bacterial vaginosis however the high prevalence of asymptomatic vaginal dysbiosis limits their specificity. Molecular typing of T. vaginalis demonstrated a two-genotype population structure, where genotype I was more likely to be infected with a virus, which subsequently associated with reporting urogenital symptoms by the patient. T. vaginalis infections positively associated with age and infections were rare among men in the Netherlands.