Insights into the vaginal microbiome in a diverse group of women of African, Asian and European ancestries.

Background: Intra-continentally, vaginal microbiome signatures are reported to be significantly different between Black and Caucasian women, with women of African ancestry having the less well defined heterogenous bacterial community state type (CST) deficient of species (CST IV). The objective of this study was to characterize the vaginal microbiomes across a more diverse intercontinental group of women ( = 151) of different ethnicities (African American, African Kenyan, Afro-Caribbean, Asian Indonesian and Caucasian German) using 16S rRNA gene sequence analysis to determine their structures and offer a comprehensive description of the non- dominant CSTs and subtypes.

Results: In this study, the bacterial composition of the vaginal microbiomes differed significantly among the ethnic groups. spp. (. and . ) dominated the vaginal microbiomes in African American women (91.8%) compared to European (German, 42.4%), Asian (Indonesian, 45.0%), African (Kenyan, 34.4%) and Afro-Caribbean (26.1%) women. Expanding on CST classification, three subtypes of CST IV (CST IV-A, IV-B and IV-C) ( = 56, 37.1%) and four additional CSTs were described: CST VI -dominant ( = 6, 21.8%); CST VII (-dominant, = 1, 0.66%); CST VIII ( = 9, 5.96%), resembling aerobic vaginitis, was differentiated by a high proportion of taxa such as , and (relative abundance [RA] > 50%) and CST IX ( = 7, 4.64%) dominated by genera other than , or (., and ). Within the vaginal microbiomes, 32 "taxa with high pathogenic potential" (THPP) were identified. Collectively, THPP (mean RA ~5.24%) negatively correlated (r = -0.68, < 2.2e-16) with species but not significantly with / spp. combined (r = -0.13, = 0.1). However, at the individual level, exhibited moderate positive correlations with (r = 0.46, = 2.6e-09) and spp. (r = 0.47, = 1.4e-09).

Conclusions: These findings while supporting the idea that vaginal microbiomes vary with ethnicity, also suggest that CSTs are more wide-ranging and not exclusive to any particular ethnic group. This study offers additional insight into the structure of the vaginal microbiome and contributes to the description and subcategorization of non-dominated CSTs.