The association between ethnicity and vaginal microbiota composition in Amsterdam, the Netherlands

Abstract

Objective: To evaluate whether ethnicity is independently associated with vaginal microbiota (VMB) composition in women living in Amsterdam, the Netherlands, as has been shown for American women.

Methods: Women (18-34 years, non-pregnant, N = 610) representing the six largest ethnic groups (Dutch, African Surinamese, South-Asian Surinamese, Turkish, Moroccan, and Ghanaian) were sampled from the population-based HELIUS study. Sampling was performed irrespective of health status or healthcare seeking behavior. DNA was extracted from self-sampled vaginal swabs and sequenced by Illumina MiSeq (16S rRNA gene V3-V4 region).

Results: The overall prevalence of VMBs not dominated by lactobacilli was 38.5%: 32.2% had a VMB resembling bacterial vaginosis and another 6.2% had a VMB dominated by Bifidobacteriaceae (not including Gardnerella vaginalis), Corynebacterium, or pathobionts (streptococci, staphylococci, Proteus or Enterobacteriaceae). The most prevalent VMB in ethnically Dutch women was a Lactobacillus crispatus-dominated VMB, in African Surinamese and Ghanaian women a polybacterial G. vaginalis-containing VMB, and in the other ethnic groups a L. iners-dominated VMB. After adjustment for sociodemographic, behavioral and clinical factors, African Surinamese ethnicity (adjusted odds ratio (aOR) 5.1, 95% confidence interval (CI) 2.1-12.0) and Ghanaian ethnicity (aOR 4.8, 95% CI 1.8-12.6) were associated with having a polybacterial G. vaginalis-containing VMB, and African Surinamese ethnicity with a L. iners-dominated VMB (aOR 2.8, 95% CI 1.2-6.2). Shorter steady relationship duration, inconsistent condom use with casual partners, and not using hormonal contraception were also associated with having a polybacterial G. vaginalis-containing VMB, but human papillomavirus infection was not. Other sexually transmitted infections were uncommon.

Conclusions: The overall prevalence of having a VMB not dominated by lactobacilli in this population-based cohort of women aged 18-34 years in Amsterdam was high (38.5%), and women of sub-Saharan African descent were significantly more likely to have a polybacterial G. vaginalis-containing VMB than Dutch women independent of modifiable behaviors.

Fig 1. Hierarchical clustering of participants by VMB composition.

AV = Atopobium vaginae; BVAB1 = BV-associated bacterium 1; GV = Gardnerella vaginalis; L = Lactobacillus; OTU = operational taxonomic unit; VMB = vaginal microbiota. A. The 20 VMB clusters obtained by hierarchical clustering of 546 vaginal samples. Clustering was based on the relative abundance of 455 OTUs. B. Heatmap showing the relative abundance of the most abundant OTUs using the color key on the left.

Fig 2. Prevalence of VMB groups by ethnic group.

L = Lactobacillus; GV = Gardnerella vaginalis; VMB = vaginal microbiota. *Excluding GV. A. Prevalence of six VMB groups by ethnic group. The error bars show the 95% confidence intervals for the prevalence of the three Lactobacillus-dominated VMB groups combined and the three VMB groups not dominated by lactobacilli combined for each ethnic group. B. The ‘Other VMB’ group was further subdivided into three subgroups: The prevalence of these subgroups is shown by ethnic group.