The vaginal microbiome in health and disease

The community, or the residents of viruses, fungi, bacteria, and other tiny things that live on the skin and in the gut, also live in the vagina.

What is this community known as the vaginal microbiome?¹

The term microbiome refers to the genetic material of a community of microbes, which may include fungi, viruses, and bacteria, among other microorganisms. The vaginal microbiome is the complex ecosystem of microorganisms, including fungi, and bacteria, that can live inside the vagina. The vaginal microbiome plays a major role in reproductive and overall health. There are several factors that can impact the composition of the vaginal microbiome, which can differ from woman to woman.

What is a healthy vaginal microbiome?²

As such, there is no specific composition of microorganisms that can be considered a healthy vaginal microbiome. Instead, the specific composition of this microbiome changes from woman to woman.

As we know, a vaginal microbiome is dominated by Lactobacillus and has consistently been identified as a key to a healthy microbiome, as it can offer a greater degree of infection protection than a more diverse vaginal microbiome.

Likewise, many other vaginal microbiomes with a low proportion of Lactobacillus and a very high proportion of facultative and obligate anaerobic bacteria (such as Atopobium, Prevotella, Sneathia, and Gardnerella) can also be considered non-optimal. Such a sub-optimal vaginal microbiome has been associated with an increased risk of acquiring and transmitting STIs, a higher incidence and prevalence of the human papillomavirus, and an increased risk of cervical cancer, among other problems.

Types of Vaginal Microbiome³

Among women of reproductive age, genetic studies have identified four different microbial compositions of the vaginal microbiome, each is dominated by a unique species of Lactobacillus. Women usually have one of these four compositions, known as community state types or CST:

1. CST I: dominated by Lactobacillus crispatus,
2. CST II: dominated by Lactobacillus gasseri,
3. CST III: dominated by Lactobacillus iners,
4. CST IV: dominated by Lactobacillus jensenii.

These groups represent bacterial compositions found in about 90% of women. The vaginal microbiome also includes a non-bacterial species, such as a fungus. However, the structure and the role of vaginal fungi (also known as a vaginal mycobiota) is still under the study, so it is also known that vaginal mycobiota is composed of members of Basidiomycota or Ascomycota, two broad groups of fungi.

How does the vaginal microbiome work?⁴

As vaginal flora is made up of various different species of bacteria, viruses, fungi and more there is one species of bacteria that plays a critical role in its health: lactobacilli or Lactobacillus bacteria, often it is referred to as the “protective” or “good” bacteria.

The lactobacilli are the MVPs of the vaginal microbiome and it also plays a critical role in keeping the vagina safe and healthy. They can do this in a few different ways:

1. Lactobacilli takes up some space on the vaginal wall to prevent other harmful bacteria from sticking around.
2. Lactobacilli can also help to reduce the inflammation in the genital area.
3. Lactobacilli also produces lactic acid which helps to maintain a low pH level (between 3.8 and 4.5), which can help to protect the vaginal microbiome against some harmful pathogens.
4. Lactobacilli also produces bacteriocins (body’s natural antibiotic) to stop disruptive bacteria from growing.

In a condition where the protective bacteria like lactobacilli in the vaginal microbiome are not in sufficient quantities, then the disruptive bacteria like Gardnerella, E.coli, Mycoplasma can take over and can cause vaginal dysbiosis. Vaginal dysbiosis is a broad term used to describe a state of imbalance in the vaginal microbiome.

What causes vaginal imbalance:⁵

1. Use of antibiotics
2. Menstruation
3. Sexual activity
4. Lubricants
5. Semen
6. Candida and thrush
7. Consumption of oral contraceptive pills

Vaginal disease or disorder 

Following are the conditions which includes:

1. Bacterial vaginosis (BV)
2. Urinary tract infections
3. Urethritis
4. Vulvovaginal candidiasis
5. Endometriosis
6. Cervicitis
7. Aerobic vaginitis (AV)

Does the vaginal microbiome change?⁶

The vaginal microbiome shifts with hormones, behaviors, and more. There are various reasons that the vaginal microbiome can change, but some common ones include:

• Being pregnant or post-partum
• Changing birth control method
• Going through menopause
• Cyclical hormonal fluctuations
• Consuming certain supplements/ medications
• Stress
• Smoking
• Use of feminine hygiene products
• Menstrual blood in the vagina

The impact of vaginal microbiome on overall health⁷

The vaginal microbiome composition doesn’t just affect vaginal infections and symptoms; but also it plays a very crucial role in female health, and emerging research has uncovered some ground breaking insights into how it can affect our overall well-being (beyond the vagina) and its balance can be influenced by various factors, including diet and lifestyle. Nutraceutical products and natural remedies have gained attention for their potential to support a healthy vaginal microbiome. Also, the incorporation of probiotics for women into women’s diets may assist in preserving the delicate balance of the vaginal microbiota, potentially reducing the risk of infection and promoting optimal reproductive health.

It has been proven that having a disrupted vaginal microbiome can also create a favorable environment for the infectious microorganisms to enter or increase inflammation and can also inhibit the immune response within reproductive tract, affecting the rest of the reproductive organs.

When the protective bacteria like lactobacilli dominate the vaginal microbiome, it can also make it harder for disruptive microbes to thrive, keeping the immune barrier of the reproductive tract more strong and healthy.

Research has shown that having a disrupted vs. healthy vaginal microbiome is associated with very differing outcomes across:

• Fertility issues or failed IVF cycles
• Complications in pregnancy such as preterm birth, neonatal problems, miscarriage and preeclampsia.
• Cervicitis (inflammation of the cervix)
• Pelvic inflammatory diseases (PID)
• Toxic shock syndrome (TSS)

References: 

1. Buchta V. Vaginal microbiome. Ceska Gynekol. 2018 Winter;83(5):371-379. English. PMID: 30848142.
2. https://functionalmedicine.com.au/blog/what-is-the-vaginal-microbiome/
3. https://www.evvy.com/blog/vaginal-microbiome
4. Chen X, Lu Y, Chen T, Li R. The Female Vaginal Microbiome in Health and Bacterial Vaginosis. Front Cell Infect Microbiol. 2021 Apr 7;11:631972. doi: 10.3389/fcimb.2021.631972. PMID: 33898328; PMCID: PMC8058480.
5. Lewis FMT, Bernstein KT, Aral SO. Vaginal Microbiome and Its Relationship to Behavior, Sexual Health, and Sexually Transmitted Diseases. Obstet Gynecol. 2017 Apr;129(4):643-654. doi: 10.1097/AOG.0000000000001932. PMID: 28277350; PMCID: PMC6743080.
6. https://www.intibiome.com/gb/blogs/article-5.html
7. Holdcroft AM, Ireland DJ, Payne MS. The Vaginal Microbiome in Health and Disease—What Role Do Common Intimate Hygiene Practices Play?. Microorganisms. 2023 Jan 23;11(2):298.