Introduction
Women with Premature Ovarian Insufficiency (POI) present a premature reduction in ovarian activity, with serum concentration of sex hormones reduction, especially estrogen, establishing body repercussions. POI affects approximately 1% of the sexually active female population, but it increases the risk of various diseases. (1)
Studies have shown psychological repercussions, impairment of cardiovascular health; bone mass; urogenital system; reproduction; sexual function; quality of life and even a reduction of life expectancy when POI is not adequately treated. One of the pillars for POI treatment is systemic hormonal therapy (HT). (1, 2-6 )
Prolonged hypoestrogenemia also lead to vulvovaginal atrophy. Hypoestrogenism leads to macroscopic, histological and functional changes, which are progressive over time (7,8). The balance of the vaginal ecosystem is crucial to maintain vaginal health, especially in women with preserved sexual activity. Women with POI are young and expect to have sexual activity like any other woman without estrogen deficiency.
Estrogen promotes the preservation of a homeostatic (eubiotic) vaginal microenvironment. It is a key part of promoting accumulation of glycogen in the cells of the vaginal mucosa, by the action of α-amylase. A glycogen-rich vaginal milieu is propitious of Lactobacilli  proliferation, facilitated by lactic acid production and decreased pH. Therefore, the predominant presence of Lactobacillus (LB) in the vaginal ecosystem is fundamental. Lactic acid, produced by LBs, promotes an increase in the TH17 immune response and inhibits the proliferation of harmful anaerobic bacteria in the extracellular matrix of the tissue (9). However, recently, identification techniques for bacteria have revolutionized the study of microorganisms. The use of amplification, cloning techniques and subsequent analysis of sequences of bacterial genes (genes that codify for bacterial rRNA 16 S) in samples of vaginal secretion have identified the majority of species of Lactobacilli and other microorganisms. These techniques demonstrated that Lactobacilli sp don’t always correspond to the dominant species in the vagina of healthy women (10). Vaginal ecosystem of POI women studies were carried out focusing on the maturation of the epithelial cells (vaginal mucosa) and the lubrication that is obtained with HT. There is a scarce data of microbiota and the vaginal microbiome. In one of the rare literature studies with such a focus, were studied women with POI receiving HT and evaluated the vaginal microenvironment through amine testing, bacterioscopy, and fungal specific culture. The vaginal flora of these women was similar to women with same age and with preserved gonadal function (11). This flora was made up predominantly of Lactobacillus sp.
Lactobacilli  and their antimicrobial and anti-inflammatory products along with components of the epithelial mucosal barrier provide an effective first line defense against invading pathogens including bacterial vaginosis, aerobic vaginitis-associated bacteria, viruses, fungi and protozoa(9), So, the human vaginal microbiota appears to play an important role in preventing numerous urogenital diseases. . General consensus attributes this to lactic acid producing bacteria, mainly Lactobacillus sp, (12).
However, the methodology usually used for this identification has limitations in terms of the specificity for the identification of microorganisms that inhabit the human body.. A feature that has been recently studied, and has proven to be quite efficient, is the study of the microbiome. Microbiome is the totality of microorganisms, their genetic elements (genome), and interactions in a specific environment (13). Modern DNA tests have made it possible to identify most of these microorganisms, since they are not easily grown in the laboratory (14). DNA-based Microbiome studies can be categorized as amplicon specific studies or, more recently, metagenomic studies. It is a challenge not to include host DNA in the study (13). After the Amplicons are sequenced, phylogenetic molecular methods are used to infer the composition of the microbial community. To determine the identity of a phylogenetic sequence, it is compared to the complete genomic sequences available using methods such as the BLAST programs (13).
The vaginal microbiome of women with IOP has not been described. Thus, this study was developed with the objective of evaluating the vaginal flora of women with POI receiving HT verifying the microbiome by bacterial (16S rRNA) DNA extraction methods.