Molecular methods to describe the spectrum and dynamics of the vaginal microbiota

The human vagina hosts a collection of microbes that is distinct from other human surfaces and mucosal sites, with reduced microbial diversity that is likely driven by the acidic environment. The microbial ecosystem of the vagina is dominated by lactobacilli in women without bacterial vaginosis (BV), and is characterize by increased species richness, diversity, and evenness in women with BV. The use of molecular, cultivation-independent methods to describe the bacterial biota of the human vagina has revealed many novel putative anaerobes in women with BV, and has demonstrated the almost ubiquitous nature of Lactobacillus iners which is found in most women regardless of BV status. A variety of molecular tools are being employed to study the vaginal microbiota, and each approach has distinct advantages and disadvantages that are reviewed. Longitudinal studies have demonstrated that the vaginal microbiota can be highly dynamic, with dramatic shifts in bacterial composition and concentrations in response to numerous endogenous and exogenous factors.