Quantification of bacterial species of the vaginal microbiome in different groups of women, using nucleic acid amplification tests

Abstract

BackgroundThe vaginal microbiome plays an important role in urogenital health. Quantitative real time Polymerase Chain Reaction (qPCR) assays for the most prevalent vaginal Lactobacillus species and bacterial vaginosis species G. vaginalis and A. vaginae exist, but qPCR information regarding variation over time is still very limited. We set up qPCR assays for a selection of seven species and defined the temporal variation over three menstrual cycles in a healthy Caucasian population with a normal Nugent score. We also explored differences in qPCR data between these healthy women and an ‘at risk’ clinic population of Caucasian, African and Asian women with and without bacterial vaginosis (BV), as defined by the Nugent score.ResultsTemporal stability of the Lactobacillus species counts was high with L. crispatus counts of 108 copies/mL and L. vaginalis counts of 106 copies/mL. We identified 2 types of ‘normal flora’ and one ‘BV type flora’ with latent class analysis on the combined data of all women. The first group was particularly common in women with a normal Nugent score and was characterized by a high frequency of L. crispatus, L. iners, L. jensenii, and L. vaginalis and a correspondingly low frequency of L. gasseri and A. vaginae. The second group was characterized by the predominance of L. gasseri and L. vaginalis and was found most commonly in healthy Caucasian women. The third group was commonest in women with a high Nugent score but was also seen in a subset of African and Asian women with a low Nugent score and was characterized by the absence of Lactobacillus species (except for L. iners) but the presence of G. vaginalis and A. vaginae.ConclusionsWe have shown that the quantification of specific bacteria by qPCR contributes to a better description of the non-BV vaginal microbiome, but we also demonstrated that differences in populations such as risk and ethnicity also have to be taken into account. We believe that our selection of indicator organisms represents a feasible strategy for the assessment of the vaginal microbiome and could be useful for monitoring the microbiome in safety trials of vaginal products.

Lactobacillus-dominated cervicovaginal microbiota associated with reduced HIV/STI prevalence and genital HIV viral load in African women

“…Our data support the hypothesis that L. iners is less efficient than L. crispatus in preventing BV and other adverse reproductive health outcomes (Verstraelen et al, 2009;Srinivasan et al, 2010;Gajer et al, 2012;Jespers et al, 2012;Santiago et al, 2012). Recent genomic and transcriptomic studies suggest that L. iners is highly adapted to the vaginal compartment (Macklaim et al, 2011).…”

“…L. iners might also be the first Lactobacillus species to recover after dysbiosis (Gajer et al, 2012), which suggests a bidirectional relationship between L. iners and vaginal pathogens or dysbiosis. Like lactobacilli, G. vaginalis and Prevotella species are almost always present in the vaginal microbiome, but in much higher abundance in BV; some studies have noted a synergistic effect between them, perhaps due to metabolic dependencies (Ling et al, 2010;Zozaya-Hinchliffe et al, 2010;Ravel et al, 2011;Jespers et al, 2012). Several subspecies of G. vaginalis have been described, with different levels of epithelial adhesion capacity (Paramel Jayaprakash et al, 2012;Castro et al, 2013).…”

Assessment of vaginal microbiota in Brazilian women with and without bacterial vaginosis and comparison with Nugent score

“…G. vaginalis, A. vaginae, M. hominis and Mobiluncus spp. were detected at higher concentrations in vaginal microbiota of BV compared to non-BV women, corroborating the findings of recent studies [3,24,30,33,38]. In contrast, Lactobacillus spp.…”

“…Lactobacillus iners is a species associated with both healthy and abnormal vaginal microbiota [17,23,33]. Unlike Lactobacillus crispatus L. gasseri and L. jensenii, L. iners may be common and abundant in abnormal microbiota, sharing space with BV-marker organisms [3,24,33].…”

“…Therefore, the health status of female genital tract is dependent on the vaginal bacterial community [2]. In healthy individuals, the vaginal microbiota comprises mainly Lactobacillus species, particularly L. crispatus, L. gasseri, L. jensenii and L. iners [3][4][5]. Lactobacilli express different characteristics, such as specific adhesion to surface epithelial cells and antimicrobial substances, which make difficult the establishment of pathogenic microorganisms.…”