Vaginal microbiome of reproductive-age women

Abstract

The means by which vaginal microbiomes help prevent urogenital diseases in women and maintain health are poorly understood. To gain insight into this, the vaginal bacterial communities of 396 asymptomatic North American women who represented four ethnic groups (white, black, Hispanic, and Asian) were sampled and the species composition characterized by pyrosequencing of barcoded 16S rRNA genes. The communities clustered into five groups: four were dominated by Lactobacillus iners, L. crispatus, L. gasseri, or L. jensenii, whereas the fifth had lower proportions of lactic acid bacteria and higher proportions of strictly anaerobic organisms, indicating that a potential key ecological function, the production of lactic acid, seems to be conserved in all communities. The proportions of each community group varied among the four ethnic groups, and these differences were statistically significant [χ 2 (10) = 36.8, P < 0.0001]. Moreover, the vaginal pH of women in different ethnic groups also differed and was higher in Hispanic (pH 5.0 ± 0.59) and black (pH 4.7 ± 1.04) women as compared with Asian (pH 4.4 ± 0.59) and white (pH 4.2 ± 0.3) women. Phylotypes with correlated relative abundances were found in all communities, and these patterns were associated with either high or low Nugent scores, which are used as a factor for the diagnosis of bacterial vaginosis. The inherent differences within and between women in different ethnic groups strongly argues for a more refined definition of the kinds of bacterial communities normally found in healthy women and the need to appreciate differences between individuals so they can be taken into account in risk assessment and disease diagnosis. T he human body harbors microorganisms that inhabit surfaces and cavities exposed or connected to the external environment. Each body site includes ecological communities of microbial species that exist in a mutualistic relationship with the host. The kinds of organisms present are highly dependent on the prevailing environmental conditions and host factors and hence vary from site to site. Moreover, they vary between individuals and over time (1). The human vaginal microbiota seem to play a key role in preventing a number of urogenital diseases, such as bacterial vaginosis, yeast infections, sexually transmitted infections, urinary tract infections (2-9), and HIV infection (10, 11). Common wisdom attributes this to lactic acid-producing bacteria, mainly Lactobacillus sp., that commonly inhabit the vagina. These species are thought to play key protective roles by lowering the environmental pH through lactic acid production (12, 13), by producing various bacteriostatic and bacteriocidal compounds, or through competitive exclusion (13-16). The advent of culture-independent molecular approaches based on the cloning and sequencing of 16S rRNA genes has furthered our understanding of the vaginal microbiota by identifying taxa that had not been cultured (17-24). However, this technique is limited by high cost and low throughput, hence only small ...

High molecular weight hyaluronic acid: a two‐pronged protectant against infection of the urogenital tract?

“…It is proposed that the lactic acid maintains an acid pH which helps to protect the vaginal tissues from colonisation by potential uropathogens including E. coli . Postmenopausal women are characterised by reduced oestrogen levels and those suffering rUTIs typically show a vaginal pH above 4.5,12 suggesting that the reduced oestrogen levels impact negatively on Lactobacilli growth, which adversely affects the vaginal microbiome 13, 14, 15. In support of a role for oestrogen in the innate defence of the urogenital tract, topical, but not oral oestrogen treatments have proven successful in reducing infections with these effects mediated through the vaginal commensal populations and the urogenital innate defences 16, 17, 18, 19.…”

Bacterial communities forming the vaginal micro-ecosystem in norm and in bacterial vaginosis

“…Впервые кластеризация микробных сооб-ществ влагалища, охарактеризованных с ис-пользованием технологий глубокого секве-нирования ДНК, была проведена в 2011 г. J. Ravel et al [10]. Изучая микробиоту влага-лища у здоровых женщин репродуктивного возраста (n = 396), исследователи выделили пять основных групп.…”

“…В нашей предыдущей рабо-те по разработке критериев диагностики БВ с использованием теста Фемофлор-16 мы по-казали, что эти бактерии имеют значимую ассоциацию с БВ [9]. Наши данные не соот-ветствуют результатам работ, проведенных с применением технологий глубокого секве-нирования ДНК, согласно которым бактерии рода Eubacterium выявляются в незначитель-ном числе образцов и их содержание отно-сительно невелико [10,11,15]. Объяснением этому может служить то, что род Eubacterium отличается исключительной гетерогенностью, включая целый ряд видов с различающими-ся фенотипами.…”

Current views on vaginal microbiota and its impact on pregnancy outcomes

“…Дальнейшие исследования показали, что данный вид часто встречается при БВ, обнаруживается у женщин с антенатальными потерями плода в анамнезе [15,16]. Однако L. iners нередко встречается в качестве доминирующего вида и при нор-моценозе [17], но, в отличие от других видов лактобацилл, L. iners не препятствует раз-множению условно-патогенной микрофлоры. S. Witkin et al (2013) определили низкий уро-вень концентрации молочной кислоты во вла-галище у женщин, в составе микробиоценоза которых доминирует L. iners, и затем подтвер-дили это в лабораторных исследованиях и ре-зультатами анализа генома данного вида [18].…”

“…Также резуль-таты исследований последних лет показыва-ют, что около 25 % здоровых женщин имеют «нелакто бациллярный» тип физиологического микробиоценоза, представленный спектром анаэробных бактерий [21]. Однако у всех жен-щин с данным вариантом микробиоценоза в небольшом количестве присутствуют пред-ставители лактофлоры.…”