The vaginal microbiome is a complex ecosystem of microorganisms that inhabit the vagina. This can include beneficial, opportunistic or infectious bacteria, viruses, opportunistic fungal pathogens as well as microbial biproducts like lactic acid, hydrogen peroxide or endotoxins.
Beneficial bacteria in the vagina secrete lactic acid which helps to maintain the pH balance of the vagina and prevent overgrowth of harmful bacteria. A small amount of hydrogen peroxide produced by beneficial bacteria also protects against infections. The acidic environment created by a healthy microbiome also helps to support healthy pregnancy, and reduce the risk of gynaecological conditions like polycystic ovary syndrome and endometriosis.
The most abundant bacteria in the vaginal microbiome are ideally Lactobacilli. The species are classified into ‘Community State Types’ or CSTs which are vaginal microbiomes dominated by either Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners, Lactobacillus jensenii or a diverse spread of these.
Gardnerella vaginalis, Ureaplasma species, Prevotella species, Atopobium vaginae and Streptococcus agalactiae are some opportunistic bacteria that can take up space on the vaginal walls if the pH becomes too high (above 4.5).
Thrush is a condition caused by overgrowth of Candida species in the vagina. This is typically accompanied by white crumbly discharge. Many women are likely to assume their symptoms are related to thrush, when in fact bacterial vaginosis is more common. BV is caused by the overrepresentation of anerobic species (bacteria that cannot survive in the presence of oxygen) such as Gardnerella or Ureaplasma species. Bacterial vaginosis can be asymptomatic, or may present as local itching with ‘fishy’ odour. It’s important to note that when the pH of the vagina goes above 4.5 it’s possible to have both a yeast and bacterial infection.
Dysbiosis of the vaginal microbiome is associated with increased risk of sexually transmitted infections, bacterial vaginosis, aerobic vaginitis, candidiasis/thrush, pregnancy complications, pelvic inflammatory disease, PCOS and endometriosis.
What is it?
The vaginal microbiome is a complex ecosystem of microorganisms that inhabit the vagina. The most abundant bacteria in the vaginal microbiome are ideally Lactobacilli. This species are beneficial bacteria that help maintain the pH balance of the vagina and prevent overgrowth of harmful bacteria. Opportunistic bacteria that can be found here include Gardnerella vaginalis, Ureaplasma species, Prevotella species, Atopobium vaginae and Streptococcus agalactiae.
Vaginal microbiome research is in its infancy compared to what we now know about the gut microbiome. However, we do know about the types of Lactobacillus species that dominate this ecosystem, which scientists call ‘Community State Types’ (CST). The healthiest CST is type 1 since it is associated with the highest level of protection against infections, pelvic inflammatory disease and pregnancy complications. This is because L crispatus produces the highest amount of lactic acid amongst all the Lactobacillus species. CST 4 is considered the least protective since a lack of dominant Lactobacillus species makes the vaginal environment more vulnerable to infection.
Community State Type I : Lactobacillus crispatus dominant
Community State Type II: Lactobacillus gasseri dominant
Community State Type III: Lactobacillus iners
Community State Type IV: No Lactobacillus dominance
Community State Type V: Lactobacillus jensenii
Is the vaginal microbiome linked with the gut microbiome?
You bet it is! Research suggests that a healthy gut microbiome can promote a healthy vaginal microbiome. This is because certain beneficial bacteria in the gut, such as Lactobacillus crispatus and Lactobacillus jensenii, can also be found in the vagina. When these bacteria are present in both the gut and the vagina, they may be able to work together to promote overall health.
There is some cross-communication between the vaginal and gut microbiomes. For example, changes in the gut microbiome can affect the vaginal microbiome. This is because the vagina and the gut are connected through the anus, and bacteria can travel from the gut to the vagina. Additionally, hormonal changes during menstruation, pregnancy, and menopause can also influence the vaginal flora.
How does my vaginal microbiome help my health?
Preventing infections
The vaginal microbiome plays a crucial role in women’s health, as it helps to maintain the balance of microorganisms in the vagina and prevent the overgrowth of harmful bacteria that can cause infections.
The main way that the vaginal microbiome helps women to stay healthy is by producing lactic acid, which helps to maintain a slightly acidic pH in the vagina. This acidic environment is inhospitable to many harmful bacteria and can prevent them from thriving. Additionally, the vaginal microbiota can produce other substances, such as hydrogen peroxide, that also have antimicrobial properties and can help to prevent infections.
When the balance of the vaginal microbiome is disrupted, it can lead to a variety of health problems. For example, bacterial vaginosis (BV) is a condition in which the normal balance of bacteria in the vagina is disrupted, leading to overgrowth of certain harmful bacteria. BV can cause symptoms such as itching, burning, and a fishy odor, and it can increase the risk of other infections, such as sexually transmitted infections (STIs).
The vaginal microbiome can also play a role in the development of other gynecological conditions, such as yeast infections and urinary tract infections (UTIs).
Endometriosis
One study found that women with endometriosis had different bacterial communities in their vaginal microbiome compared to women without endometriosis. Specifically, women with endometriosis had lower levels of lactobacilli and higher levels of certain types of bacteria that are associated with inflammation and infection.
Other studies have suggested that dysbiosis and inflammation may be linked to the development of endometriosis. For example, one study found that women with endometriosis had a higher prevalence of BV and other types of vaginal dysbiosis compared to women without endometriosis.
Polycystic Ovary Syndrome (PCOS)
Some studies suggest that there may be a link between dysbiosis in the vaginal microbiome and the development of PCOS.
One study found that women with PCOS had different bacterial communities in their vaginal microbiome compared to women without PCOS. Specifically, women with PCOS had lower levels of lactobacilli and higher levels of other types of bacteria that are associated with inflammation and infection.
Other studies have suggested that imbalances in the gut microbiome may also play a role in the development of PCOS. For example, some studies have found that women with PCOS have different bacterial communities in their gut microbiome compared to women without PCOS. These imbalances in the gut microbiome may contribute to metabolic dysfunction and insulin resistance, which are common features of PCOS.
Overall, while the exact role of the vaginal microbiome in PCOS is still unclear, there is growing evidence that imbalances in both the vaginal and gut microbiomes may contribute to the development and progression of this condition.
Healthy pregnancy
The vaginal microbiome plays an important role in supporting a healthy pregnancy. During pregnancy, the vaginal flora undergoes changes that are necessary for a healthy pregnancy outcome. These changes include an increase in the abundance of lactobacilli, which help to maintain a healthy vaginal pH and prevent the overgrowth of harmful bacteria.
A healthy vaginal microbiota during pregnancy has been associated with a reduced risk of adverse pregnancy outcomes, such as preterm birth and low birth weight. In contrast, an imbalanced vaginal microbiome during pregnancy, such as bacterial vaginosis (BV) or other types of dysbiosis, has been associated with an increased risk of these adverse outcomes.
The exact mechanisms are not fully understood, but it is thought that an imbalanced vaginal microbiome can lead to inflammation and infection, which can have negative effects on the developing fetus.
Additionally, research suggests that the gut microbiome may also play a role in supporting a healthy pregnancy. For example, imbalances in the gut microbiome have been associated with gestational diabetes and other pregnancy complications.