IntroductionWorldwide the most common vaginal disorder, bacterial vaginosis (BV) is an exceedingly common and medically important condition in women of reproductive age. Apart from being an obnoxious disorder, with unpleasant discharge, foul odor and pruritus, which may largely impede a woman’s sexual functioning and self image, BV has been linked to both gynaecological and especially obstetrical complications, e.g. chorioamnionitis and preterm delivery. BV is a clinical entity, understood as a spectrum of polymicrobial, ecological alterations in the vaginal environment, with a massive overgrowth of anaerobes in the absence of H2O2-producing lactobacilli, resulting in an increase in vaginal pH. Microbes play a crucial role in determining the biochemical and immunological profile of their ecological niche, which is thought to be related to the aforementioned complications. Earlier attempts to reveal individual microbial agents accounting for the pathogenesis of BV have been many, but short coming, and the etiology of the disease and the significance of the arrival and contribution of individual bacterial species in this altered polymicrobial community have remained unsettled enigmas. Several hypotheses have been put forward, from sexually transmitted pathogens to acquisition of particular Lactobacilli and polymorphisms of several genes involved in the innate immune system. Over the last decade the advent of and accessibility to new molecular techniques for the genotyping, identification and visualisation of new bacterial species and communities, that has hitherto been impossible with traditional culturing methods, has led to a completely new understanding of the complex microbiota of healthy and diseased vaginal flora. With fluorescence microscopy (FISH) a biofilm constituted of cohesive strains of Gardnerella vaginalis, frequently intermixed with the newly discovered Atopobium vaginae, has been described, and even found to be sexually transmitted and resistant to antibiotic therapy.
ObjectiveIn this article a review of the comprehensive and occasionally conflicting literature of the last decade, using culture independent methods for the study of the vaginal flora, is presented, with emphasis on demographic and ethnic variation in the microbiota. The epidemiology and possible transmissibility of BV is also briefly discussed, and the significance of the Gardnerella biofilm for the maintenance of BV and its implications for future research on BV are considered. All articles are identified through searches in PubMed.
Conclusion Using high throughput pyrosequencing, the current state of the art in the field of human metagenomics, new studies have thoroughly profiled the overall structure of vaginal microbial communities in different ethnic groups. Furthermore, the true taxonomic richness and diversity between individuals has been shown. The occurrence of dramatic shifts in bacterial loads in phyla and genera in association with BV has also been elaborated, and the time for quantitative PCR to supersede the microscopic diagnosis of BV has come. Gardnerella biofilm is probably sexually transmitted, and may well constitute the core of the pathogenesis of BV.