Gardnerella vaginalis is a bacteria that coexists alongside other bacteria in your vagina to keep it infection-free. When too much gardnerella bacteria grows, you can develop an infection called bacterial vaginosis (BV). BV is the most common vaginal infection and can be easily treated with antibiotics.
Gardnerella vaginalis is one type of bacteria inside your vagina. It’s part of what’s known as your microbiome or vaginal flora. Your vaginal flora includes different varieties of bacteria and different amounts of these bacteria that keep your vagina healthy. The bacteria coexist in a delicate balance.
When your levels of gardnerella are in balance with the other bacteria, your vaginal flora prevents you from getting infections. If there’s an imbalance and too much gardnerella grows, you can get a vaginal infection called bacterial vaginosis (BV).
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When Gardnerella was first discovered in 1955, it was thought of as a “bad” bacteria that caused vaginal infections. The thinking that Gardnerella led to infection was so accepted that people referred to what we now know as BV, a specific kind of vaginal infection, as simply “Gardnerella vaginosis.” People named the infection after the bacteria they thought caused it.
Since then, research has shown that things aren’t so straightforward. People with vaginal infections have Gardnerella bacteria in their vaginas, but people without vaginal infections have Gardnerella, too. This means that Gardnerella alone isn’t to blame for vaginal infections. BV is caused by many other bacteria like atopobium vaginae and megasphera. However, Gardnerella is isolated in the majority of cases.
We now know that Gardnerella plays a role in maintaining a healthy PH, or a healthy amount of acidity, in your vaginal fluid. A healthy vagina has a PH range of 3.8-4.5. It’s considered to have a moderate amount of acid. The bacteria that make up your vaginal flora, including Gardnerella, work to maintain this level of acidity, which is just the right amount of acid for fighting infection. When the acidity levels drop, too much Gardnerella grows, and that’s when an infection can occur.
In other words, Gardnerella's purpose depends on how much you have of it. Having too much Gardnerella bacteria is a sign of BV. Lack of lactobacillus or the wrong composition of lactobacillus creates an imbalance in the presence of Gardnerella, leading to BV. Having the right amount of Gardnerella and lactobacillus means that your vaginal flora is in balance and infection-free.
Gardnerella lives inside your vagina, as one of many microorganisms that are part of your vaginal flora.
Gardnerella (a bacteria) is often confused with BV (a specific kind of vaginal infection). And sometimes Gardnerella and BV both are mistaken for sexually transmitted infections (STIs). But Gardnerella isn’t the same as BV, and it isn’t considered a sexually transmitted bacteria (at least not officially).
No. But Gardnerella is associated with BV. And having too much Gardnerella in your vaginal fluid is a sign that you have BV.
You get BV when the delicate balance of bacteria that keeps your vaginal flora healthy becomes disturbed. It’s unclear what causes this imbalance. But the amount of two different kinds of bacteria in your vagina lactobacilli bacteria and Gardnerella bacteria – is key.
People with BV have too little lactobacilli bacteria in their vaginas and too much Gardnerella bacteria. Lactobacilli bacteria help keep your vagina acidic. Not having enough lactobacilli bacteria causes your vaginal PH to increase to 4.6 or more, so that your vagina isn’t acidic enough. In this environment, Gardnerella starts to multiply, and other bacteria begin to cling to the Gardnerella bacteria and grow, too. When this happens, you get BV. But Gardnerella alone doesn’t cause BV. An imbalance in your vaginal flora causes BV.
No. Gardnerella isn’t an STI. But it’s a bacteria that’s most likely transmitted sexually. And this can be confusing. Gardnerella isn’t considered a sexually transmitted bacteria, like the bacteria that cause gonorrhea, syphilis or chlamydia, for a few reasons:
Just because Gardnerella isn’t an STI-causing bacteria doesn’t mean that sexual activity isn’t a risk factor when it comes to getting BV. It is. The causes of BV are unknown, but you’re more likely to get an infection if you have multiple sex partners or if you have a new sex partner.
Gardnerella isn’t something that you can catch. Instead, Gardnerella vaginalis is a natural part of the environment in your vagina. You can get BV if too much Gardnerella grows. Causes of BV are unknown, but people with more sex partners and multiple sex partners are more at risk for getting BV.
If too much Gardnerella begins to grow, you may start to notice changes in your vaginal discharge that are signs of BV. The fluid from your vagina may:
You can have BV without having any symptoms at all. Whether BV causes symptoms or not, you should see your provider and get treated if you have BV.
Your provider can look at your vaginal fluid under a microscope to check for Gardnerella vaginalis bacteria.
Untreated BV increases your risk for pregnancy complications, like premature birth and miscarriage. It also puts you at greater risk of contracting STIs. Your provider may prescribe oral or intravaginal antibiotics to return your Gardnerella to healthy levels and resolve your BV.
A note from Cleveland Clinic
Don’t be alarmed if you learn that you have Gardnerella vaginalis bacteria. It’s a common type of bacteria that’s supposed to be in your vagina. If your provider tells you that you have an overgrowth of Gardnerella or that you have BV, rest assured that the condition is treatable. A course of antibiotics can get your vaginal flora back to healthy levels within about a week.
Last reviewed by a Cleveland Clinic medical professional on 11/01/2021.
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