Vaginal microbiome in women from Greenland assessed by microscopy and quantitative PCR

Raluca Datcu,Elisabeth Rink,Jørgen Skov Jensen,Ruth Montgomery-Andersen,Gert Mulvad,Anders Koch,Peter Ahrens,Dionne Gesink

doi:10.1186/1471-2334-13-480

Abstract

BackgroundBacterial vaginosis (BV) is a common condition, although its aetiology remains unexplained. The aim of this study was to analyse the composition of vaginal microbiota in women from Greenland to provide a quantitative description and improve the understanding of BV.MethodsSelf-collected vaginal smears and swabs were obtained from 177 women. The vaginal smears were graded for BV according to Nugent’s criteria. The vaginal swab samples were analysed by 19 quantitative PCRs (qPCRs) for selected vaginal bacteria and by PCR for four sexually transmitted infections (STIs).ResultsSTIs were common: Mycoplasma genitalium 12%, Chlamydia trachomatis 7%, Neisseria gonorrhoeae 1%, and Trichomonas vaginalis 0.5%. BV was found in 45% of women, but was not associated with individual STIs. Seven of the 19 vaginal bacteria (Atopobium vaginae, Prevotella spp., Gardnerella vaginalis, BVAB2, Eggerthella-like bacterium, Leptotrichia amnionii, and Megasphaera type 1) had areas under the receiver operating characteristic (ROC) curve > 85%, suggesting they are good predictors of BV according to Nugent. Prevotella spp. had the highest odds ratio for BV (OR 437; 95% CI 82–2779) in univariate analysis considering only specimens with a bacterial load above the threshold determined by ROC curve analysis as positive, as well as the highest adjusted odds ratio in multivariate logistic regression analysis (OR 4.4; 95% CI 1.4-13.5). BV could be subdivided into clusters dominated by a single or a few species together.ConclusionsBV by Nugent score was highly prevalent. Two of seven key species (Prevotella spp. and A. vaginae) remained significantly associated with BV in a multivariate model after adjusting for other bacterial species. G. vaginalis and Prevotella spp. defined the majority of BV clusters.

Highlights

Bacterial vaginosis (BV) is a common condition, its aetiology remains unexplained
It is generally accepted that a healthy vaginal microbiome is dominated by Lactobacillus spp., while the replacement of these bacteria with facultative and strict anaerobes, such as Gardnerella vaginalis, Prevotella spp., Peptostreptoccocus spp., Mobiluncus spp., and a wide range of fastidious and uncultured bacteria leads to a switch from normal vaginal microbiota to bacterial vaginosis (BV) [1]
A. vaginae and G. vaginalis were present in all patients with BV by qualitative detection and in a high proportion of women with normal microbiota as determined by Nugent’s criteria

Summary

Introduction

Bacterial vaginosis (BV) is a common condition, its aetiology remains unexplained. The aim of this study was to analyse the composition of vaginal microbiota in women from Greenland to provide a quantitative description and improve the understanding of BV. An alternative scoring of vaginal smears, the Claeys’ criteria, was described [5], aiming to improve the discrimination between various morphotypes not accounted for in the Nugent score. The Claeys score is based on Ison-Hay’s criteria [6] with a more detailed evaluation of normal flora. Using the Claeys score, pregnant women with BV-like flora (grade 2 or 3), grade 1-like (small, short, irregularly shaped Gram positive rods) or 1-PMN (smears with over 50 polymorphonuclear leukocytes [PMN]/high power microscopy field in the absence of Candida) were shown to be at high risk for adverse pregnancy outcomes [7]

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