Quantifying the human vaginal community state types (CSTs) with the species specificity index

Area of Science:

• Microbiome research
• Human vaginal microbiome
• Microbial ecology

Background:

• The five community state types (CSTs) classify human vaginal microbial communities (HVMC), aiding in understanding bacterial vaginosis (BV) etiology.
• Current CST classification is qualitative, lacking quantitative criteria for reliable distinction.
• Inter-subject and intra-subject variability in HVMC is significant and difficult to quantify.

Purpose of the Study:

• To develop a quantitative tool for reliably distinguishing between the five CSTs of the human vaginal microbiome.
• To provide a mechanistic interpretation of the CST scheme using species specificity and a novel specificity aggregation index (SAI).

Main Methods:

• Application of species specificity (Mariadassou et al., 2015).
• Introduction and application of the specificity aggregation index (SAI).
• Validation using cross-sectional (400 individuals) and longitudinal (32 individuals) cohort studies.

Main Results:

• The developed quantitative tool accurately characterized the five CSTs.
• The tool demonstrated reliability across both cross-sectional and longitudinal datasets.
• A mechanistic interpretation of CSTs was provided via the specificity continuum paradigm.

Conclusions:

• The new quantitative tool facilitates accurate application of the CST scheme for HVMC.
• This approach offers potential for microbiome typing, including gut enterotypes.
• Advances contribute to a deeper understanding of microbial community structure and function.