Factors associated with the composition and diversity of the cervical microbiota of reproductive-age Black South African women: a retrospective cross-sectional study.

Harris Onywera,Anna-Lise Williamson,Zizipho Z.A Mbulawa,Tracy L Meiring,David Coetzee

doi:10.7717/peerj.7488

Harris Onywera, Anna-Lise Williamson + Show 3 more

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https://doi.org/10.7717/peerj.7488

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Abstract

BackgroundLactobacillus spp. are common bacteria in the cervical and vaginal microbiota (CVM) and are thought to represent a “healthy” cervicovaginal state. Several studies have found an independent association between ethnicity/race and cervical and vaginal microbiota (CVM) composition. Women of sub-Saharan African descent appear to be significantly more likely to have non-Lactobacillus-dominated CVM compared to women of European descent. The factors contributing to these differences remain to be fully elucidated. The CVM of Black South African women and factors influencing their CVM remain understudied. In this study, we characterized the cervical microbiota of reproductive-age South African women and assessed the associations of these microbiota with participants’ metadata.MethodsThe cervical microbiota from cervical DNA of 62 reproductive-age women were profiled by Ion Torrent sequencing the V4 hypervariable region of the bacterial 16S ribosomal RNA (rRNA) gene and analyzed with the Quantitative Insights Into Microbial Ecology (QIIME), UPARSE, and metagenomeSeq tools. Associations between cervical microbiota and participants’ metadata were assessed using GraphPad Prism, R packages and an in-house script.ResultsThe cervical microbiota clustered into three distinct community state types (CSTs): Lactobacillus iners-dominated cervical microbiota (CST I (38.7%, 24/62)), unclassified Lactobacillus-dominated cervical microbiota (CST II (4.8%, 3/62)), and diverse cervical microbiota (CST III (56.5%, 35/62)) with an array of heterogeneous bacteria, predominantly the bacterial vaginosis (BV)-associated Gardnerella, Prevotella, Sneathia, and Shuttleworthia. CST III was associated with BV (p = 0.001). Women in CST I were more likely to be on hormonal contraception, especially progestin-based, compared to women in CST III (odds ratio: 5.2 (95% CI [1.6–17.2]); p = 0.005). Women on hormonal contraception had a significantly lower alpha (Shannon indices: 0.9 (0.2–1.9) versus 2.3 (0.6–2.3); p = 0.025) and beta (permutational multivariate analysis of variance (PERMANOVA) pseudo-F statistic =4.31, p = 0.019) diversity compared to non-users. There was no significant difference in the alpha (Shannon indices: 1.0 (0.3–2.2) versus 1.9 (0.3–2.2); p = 0.483) and beta (PERMANOVA pseudo-F statistic = 0.89, p = 0.373) diversity in women with versus without human papillomavirus infection.ConclusionsThe majority of Black women in our study had non-Lactobacillus-dominated cervical microbiota. Additional studies are needed to examine whether such microbiota represent abnormal, intermediate or variant states of health. Lastly, the association of hormonal contraception with L. iners dominance requires further in-depth research to confirm this association, determine its biological mechanism and whether it has a beneficial effect on the cervicovaginal health.

Highlights

It is generally acknowledged that Lactobacillus spp., Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners, and Lactobacillus jensenii, are common bacteria in the cervical and vaginal microbiota (CVM) (Huang et al, 2015; Ravel et al, 2011; Smith et al, 2012) and are regarded as biomarkers of health (Huang et al, 2015; Petrova et al, 2015; Ravel et al, 2011)
South African women have a high prevalence of bacterial vaginosis (BV) (31–63%) (Abbai, Reddy & Ramjee, 2016; Kenyon, Colebunders & Crucitti, 2013; Lennard et al, 2018; Onywera et al, 2019) and human papillomavirus (HPV) (16–75%) (Bruni et al, 2019) yet there is paucity of knowledge on the CVM of Black South African women as the existing CVM studies have mostly focussed on women of White, Asian, Hispanic, and African American background
HPV and high-risk HPV infections were detected in 37.1% and 29.0% of the women, correspondingly

Summary

Introduction

It is generally acknowledged that Lactobacillus spp., Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners, and Lactobacillus jensenii, are common bacteria in the cervical and vaginal microbiota (CVM) (Huang et al, 2015; Ravel et al, 2011; Smith et al, 2012) and are regarded as biomarkers of health (Huang et al, 2015; Petrova et al, 2015; Ravel et al, 2011). Loss of lactobacilli concomitantly with overgrowth of anaerobic and microaerophilic bacteria, which can be Gram-positive, Gram-negative, and/or Gram-variable bacteria, results in bacterial vaginosis (BV) (Hillier, 1993; Sobel, 2000), the most common form of vaginal disorder among reproductive-age women (Kenyon, Colebunders & Crucitti, 2013). Lactobacillus spp. are common bacteria in the cervical and vaginal microbiota (CVM) and are thought to represent a ‘‘healthy’’ cervicovaginal state. We characterized the cervical microbiota of reproductive-age South African women and assessed the associations of these microbiota with participants’ metadata.

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