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

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.

Bacterial Vaginosis Diagnosed by Analysis of First-Void-Urine Specimens

“…Participants were recruited from the general population via the population registry, by direct contact via telephone calls, and by advertising in local media as previously described (14). The initial objective of this study was to determine the epidemiology of sexually transmitted infections (STIs) (14) and BV in Greenland (10). Each participant completed an interviewer-administered sexual health survey in either Greenlandic or Danish and provided a self-obtained vaginal smear, a vaginal swab sample collected with a flocked swab in UTM (Copan, Brescia, Italy), and an FVU sample collected in GeneLock transport medium (Sierra Molecular Corp., Sonora, CA) as previously described (14).…”

“…For the uncultured bacteria BVAB 2, Megasphaera type 1, and Eggerthella-like bacterium, the 16S rRNA gene PCR product from a positive clinical sample was used as positive control after gel purification and DNA sequencing for verification (10). Standard curves for quantitative PCRs were generated using 10-fold dilutions from 10 7 genome equivalents (geq)/l to 1 geq/l in TE buffer containing 1 g/ml of calf thymus DNA (D-8661; Sigma-Aldrich).…”

“…qPCRs for A. vaginae, L. amnionii, BVAB 2, Megasphaera type 1, Eggerthella-like bacterium, G. vaginalis, and Prevotella spp. were performed using primers and reaction conditions previously described (10).…”

“…Several studies on the diagnosis of BV using PCR have been published recently (9)(10)(11)(12)(13), but all these have used PCR for BVassociated bacteria in vaginal swabs. In some studies, vaginal swabs are not collected, and first-void urine (FVU) may be the only material from which BV can be diagnosed.…”

“…In most settings, pregnant women are traditionally screened for glucose and leukocytes in urine, and thus urine would be easy to collect for BV studies. Therefore, we aimed to determine whether BV can be diagnosed from FVU by PCR using a panel of BV-associated bacteria that were the most sensitive and specific indicators for predicting BV in vaginal swabs compared to the Nugent score after applying receiver operating characteristic (ROC) curve analysis (10). ROC curve analysis establishes a threshold/cutoff for optimal diagnosis of BV by quantitative PCR (qPCR) by analyzing samples with known normal and BV floras as determined by the Nugent score.…”