Vaginal microbiome.

OBJECTIVE: Presentation of complex information about the vaginal microbiota from historical view to current concepts with focus on latest findings on the structure and functioning of the vaginal microbiome. DESIGN: Review article. SETTING: Department of Clinical Microbiology, University Hospital and Faculty of Medicine in Hradci Králové, Charles University in Prague. METHODS: Literature review using the databases (PubMed, Web of Science, Ovid, etc.) with keywords (vaginal microbiota/ microbiom; vaginal discharge; bacterial vaginosis; vulvovaginitis; vaginal Lactobacillus). RESULTS: The vaginal microbiome is a specific compartment of the human microbiome. Unique conditions of the vagina are characterized by a few microbial species, usually lactobacilli, which are able to utilize glycogen, which is under control of estrogens. Lactobacilli and other fermentative bacteria together with vaginal epithelial cells produce lactic acid and are responsible for acidifying vaginal milieu. Lactic acid occurs in two isomeric forms, and their relative ratio is likely to give the vaginal microbiota a certain degree of stability and ability to withstand some infections. This microbiota is manifested by a low degree of diversity and by the high dynamics of changes of its composition under the influence of various exogenous and endogenous factors. Increase in diversity can be paradoxically associated with a dysbiosis such as bacterial vaginosis. Individual species of lactobacilli mainly Lactobacillus crispatus characterize the main community state types in the vagina. Apart from lactobacilli, healthy women may be colonized with a non-lactobacillary microbiota whose rate is dependent on ethnicity. CONCLUSION: The definition of vaginal microbiota cannot be only related to the presence or absence of individual microorganisms, although the incidence of some of them can be correlated with dysbiosis or eubiosis. The composition of microbiota is important, but it is only one of the basic attributes of normal vaginal microbiota, but not sufficient; that is the functional definition of vaginal microbiota in relation to its structure and dynamics, including the influence of ethnicity, physiological status of the vagina, and genetic disposition of woman.