Characteristics and physiologic role of female lower genital microbiome.

Márta Marschalkó, Luca Ambrus

Vaginal microbiome is substantial in the maintenance of vaginal health and defense against pathogenic microorganisms. New techniques, including next-generation sequencing broadened our knowledge with new findings on the composition and functions of the vaginal microbiome. Improvement of laboratory techniques provides a better understanding of the diverse patterns of the vaginal microbiome in reproductive-age women and their longitudinal changes in both healthy and dysbiotic conditions. The objective of this review was to summarize the basic learning of the vaginal microbiome. In the era of traditional cultivation-dependent techniques, the role of Lactobacilli in maintenance of the vaginal homeostasis, in lactic acid and various antimicrobial compounds production and in genital defense has been delineated. Much of our knowledge about the healthy microbial flora comes from cultivation-independent molecular-based techniques. The vaginal microbiome alters throughout a woman's life, its function develops fully in reproductive age. Healthy vaginal flora typically shows Lactobacillus predominance with a pH lower than 4.5, the healthy flora is dominated by one or two species of Lactobacillus, predominantly L. crispatus, L. iners, L. gasseri, L. jensenii. The review provides background on the 5 community state types of Lactobacillus communities, their characteristics, demographic occurrence, the type shifts, the terminal changes of the dominant bacterial communities, and the comparison of them to non-Lactobacillus dominated healthy microbiomes. The microbiome contributes to the local immune response of the vaginal mucous membrane, in defense to pathogens and maintenance of immunologic tolerance to physiologic changes. Bacterial vaginosis is a clinical syndrome characterized by pathologic vaginal microbiome, Lactobacillus community decreased in abundance and replaced by different anaerobes with great diversity. In pregnant women, bacterial vaginosis increases the risk of miscarriage, abortion, preterm birth, chorioamnionitis and endometritis. In non-pregnant women, bacterial vaginosis is associated with an increased risk of upper genital tract and urinary tract infections. Women with bacterial vaginosis are more sensitive to sexually transmitted infections and acquisition of HIV. Women with bacterial vaginosis may transmit HIV virus to their partner and newborn. Orv Hetil. 2023; 164(24): 923-930.