The 5 functions of the vaginal flora (and how to take care of it) - medical - 2023



In recent years, the vaginal microbiota, commonly known as vaginal flora, has been gaining prominence in the care of women's sexual and reproductive health. Indeed, it appears that having a healthy vaginal microbiota can be synonymous with health.

First described by the gynecologist Döderlein in 1894, it is a complex ecosystem consisting mainly of bacteria of the genus Lactobacillus. Although their composition differs between people and evolves throughout life, they act as powerful stabilizers of the vaginal environment.

Lactobacilli are very intimately associated with the vaginal mucosa and act as a protective shield against genital tract infections. In addition, there are a series of pathologies associated with the decrease in the population of lactobacilli.

So, in today's article we will see what the vaginal flora consists of, what its functions are and what happens when this natural barrier is altered.

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What is the vaginal flora?

An infinity of microorganisms inhabit the vagina that make up the cervicovaginal ecosystem. This set of microorganisms, which are called the microbiota, coexist in a dynamic equilibrium and establish complex connections with each other.

Today, it is known that this microbiota does not present too high a diversity (in terms of species) and is characterized by having a high abundance of bacteria of the genus Lactobacillus.

Lactobacillus being the predominant bacteria, healthy women of reproductive age usually show species such as Lactobacillus crispatus, L. iners, L. jensenii or L. gasseri. The proportion of these can differ in each woman and it has been seen that one species usually dominates over the others.

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In addition to the aforementioned species, about 250 bacterial species have been described, What Atopobium vaginae Y Gardnerella vaginalisas well as the fungus Candida albicans. Its presence and abundance depend on factors such as ethnicity, environment and sexual activity, among others. However, the latter two can proliferate uncontrollably and generate opportunistic infections.

The natural reservoir for vaginal lactobacilli is the intestine.When women enter puberty, bacteria migrate from the anus and reach the vagina through the perineum and vulva. It could therefore be said that the vaginal microbiota "inherits" part of the bacteria from the intestinal microbiota.

Visual representation of "Lactobacillus", the predominant bacterial genus of the vaginal flora.

However, factors such as age, pregnancy, and receiving pharmacological treatments can change the composition of this microbiome. For example, during pregnancy there is a large increase in lactobacilli as a result of the increased production of hormones. On the other hand, during menopause, the amount of lactobacilli decreases and this generates the well-known vaginal dryness.

These lactobacilli live in the vagina without causing disease while promoting proper maintenance of vaginal balance. And this is not all: thanks to their presence they prevent colonization and mitigate the growth of other adverse microorganisms, including those that are the cause of sexually transmitted infections. This defensive function is exercised by generating a protective layer and producing antimicrobial compounds.

What functions does it perform?

Since the first microbiological study of the human vagina, carried out in 1894, the lactobacilli have been described as the main "inhabitants" of the female genital tract. For this reason, it is considered that they have a fundamental role in the maintenance of the vaginal ecosystem since they can prevent the excessive proliferation of other opportunistic microorganisms that inhabit the vagina.

In the same way, they also prevent the colonization of other pathogens that can generate urogenital pathology infections (for example, a urine infection). As we have commented previously, when Gardnerella vaginalis Overgrowing can lead to bacterial vaginosis, a process known as an opportunistic infection. The defensive functions are exercised through the following mechanisms:

1. They form a protective layer

Lactobacilli adhere to the vaginal mucosa in a very specific way. Because they have surface structures called adhesins, they recognize receptors on the epithelial surface and form a junction.

It is precisely this association between lactobacilli and the vaginal epithelium that ends up generating a biofilm that protects the mucosa against colonization by unwanted microorganisms.

2. They produce lactic acid

The vagina has a pH of approximately 4, which indicates that it is a cavity with an acidic environment. But where does this acidity come from? Epithelial cells, especially in fertile women, tend to accumulate glycogen which is converted to lactic acid by lactobacilli through fermentation. It is precisely this lactic acid that generates these acidic conditions that inhibit the growth of other pathogens.

3. Produce antimicrobial compounds

Lactobacilli also have the ability to produce hydrogen peroxide, which is known to have a bactericidal effect (which kills bacteria). In addition, it has been seen that this effect is enhanced by the presence of other typical compounds of uterine mucus such as chloride, the concentration of which rises during ovulation.

They also generate a multitude of bacteriocins: peptides with antimicrobial activity with the property of destroying other cells, as well as surfactants. The latter have the ability to solubilize the envelopes of other unwanted microorganisms.

4. Coaggregate with other pathogens

These bacteria that make up this important protective layer also have aggregating abilities. This way, "Envelop" potential pathogens and in them they expel the compounds previously exposed, generating a microbicidal effect of remarkable activity.

5. They stimulate the immune system

We could not finish this section without first talking about how they help our body's surveillance system: the immune system. Although it is designed to recognize and attack all those cells that are not its own, it has been adapted so as not to attack the vaginal microbiota.

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The presence of lactobacilli in the genital tract makes the immune system always attentive and never relax. Consequently, if a pathogen reaches this area, the cells of the immune system are already ready to take action and neutralize the infection.

When the balance is upset

However, sometimes vaginal lactobacilli concentration may drop below a critical level. Under this scenario, other microorganisms that are found in the vagina to a lesser extent or others of exogenous origin can proliferate and become dominant.

The main conditions that are associated with the decrease in lactobacilli are the following:

  • Bacterial vaginosis: bacterial infection usually caused by Gardnerella vaginalis. It is usually the most common manifestation of the alteration of the vaginal microbiota.
  • Candidiasis: infection caused by the fungus Candida albicans.
  • Trichomoniasis: sexually transmitted infection caused by Trichomonas vaginalis.
  • Lower urinary tract infections: as a consequence of the presence of Enterobacteriaceae present in the feces or others.

The causes of this microbial destabilization can be very varied. It should be taken into account that the vaginal habitat undergoes frequent changes caused by its own physiology. For example, the presence of estrogens (one of the hormones that regulate the menstrual cycle) seems to favor the adherence and proliferation of Candida Y Trichomonas vaginalis.

Secondly, menstruation also causes changes in vaginal pH, making it more neutral. This circumstance makes it more difficult for lactobacilli to grow and creates a scenario where other pathogenic microorganisms are more likely to develop. Another destabilizing factor is the prolonged use of buffers, which also tend to raise the pH.

In short, the decrease in vaginal acidity is what affects the most and it could be considered a predisposing factor for the excessive proliferation of opportunistic pathogens.

In addition, it has been seen that intrauterine devices (IUDs) can also affect the correct development of the lactobacillus population, favoring the appearance of vaginosis, as well as the use of systemic antibiotics. Finally, stress and tobacco use can also have strong implications.

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How to cure the vaginal microbiota

There are a series of actions that allow to act on the balance of the microbiota. The first is through the use of probiotics, which are live bacteria. These are used when the vaginal microbiota is altered and they are made up of live microorganisms. The intention of treatment is to repopulate the vagina with beneficial bacteria. There is currently a wide range of vaginal probiotics on the market.

There are also other vaginal preparations that, although they do not contain live microorganisms, are composed of lactic acid and glycogen. Known as prebiotics, promote the growth of lactobacilli.

Finally, there are a number of tips that can help preserve your balance:

  • After urinating, it is recommended to wipe the genitals from front to back. This prevents bacteria of fecal origin from contaminating the vaginal environment.
  • Avoid the use of strong soaps for intimate hygiene that alter the vaginal pH.
  • Wear cotton underwear to promote proper perspiration in the area.

It should be taken into account that the vaginal microbiota, although it performs important protective functions, is also a highly alterable flora. Knowing about their presence is the first step to better understand women's sexual health.