Bacterial Vaginosis


  • Bacterial vaginosis (BV) is a very common disruption of the vaginal microbiome, and the cause is unknown.
  • Untreated BV may increase your risk of pelvic inflammatory disease, infertility, preterm birth, and make you more prone to acquiring a sexually transmitted infection.
  • BV is treated with antibiotics, but these often fail. There are things you can do to support your vaginal microbiome and stop BV from coming back.

Bacterial vaginosis (BV) is an overgrowth of unfriendly bacteria.

In a typical healthy vaginal community, Lactobacillus are in charge. These protective bacteria like to dominate in numbers, and while they may be fine with other microbes hanging around, they usually don’t like to share space with unfriendly bacteria.

In bacterial vaginosis (BV), unfriendly bacteria such as Gardnerella vaginalis, Fannyhessea vaginae (also known as Atopobium vaginae), Prevotella, and others steal the microphone from Lactobacillus and use it to create a disrupted environment, with an increased pH [1]–[3].

Unfortunately, what causes BV is unknown. Some factors that may contribute to it are:

  • Having a vaginal community that is naturally low in lactobacilli (CST 4)
  • Hormone changes
  • A high number of sexual partners
  • Smoking
  • Poor personal hygiene
  • Douching
  • Antibiotics [4]–[7]

Some scientists believe BV should be considered a sexually transmitted infection [8], but this is a controversial topic. Although microbes are shared through sex and this can certainly alter your vaginal microbiome, it is not absolutely necessary to have sex to get BV.

If you have BV, you are not alone

You may have had or currently have BV. Or maybe you have had it more than once. Well, there is nothing to be ashamed of, because BV is one of the most common vaginal infections in women.

In fact, one in three women gets BV at some point in their lives.

And approximately 29% of women in the US have BV [9].

Common BV symptoms

One way to know if you have BV is to pay attention to your vaginal discharge. BV discharge is characterized by:

  • A fishy odor
  • Thin texture
  • Milky white or grayish color

Other common BV symptoms are:

  • A burning sensation in your vagina
  • Itching
  • Pain during sex or urination

A shocking fact is that 84% of women diagnosed with BV have no symptoms at all [10]. But not having any symptoms doesn’t mean you are free from all the BV-associated complications.

These asymptomatic cases are more likely to be detected with molecular techniques such as next-generation sequencing, the technology we use at Tiny Health.

Three different ways of diagnosing BV

In clinical practice, BV is often diagnosed by the Amsel criteria [11]. If you have three out of four Amsel criteria, your provider will diagnose you with BV:

  • A thin white-grayish vaginal discharge
  • A fishy smell
  • Clue cells (these are vaginal epithelial cells covered in bacteria) on microscopic examination
  • A pH higher than 4.5

A second way of diagnosing BV is by using the Nugent criteria. This involves putting a vaginal fluid sample into a microscope slide, staining it and looking at it under a microscope [11]. The presence and numbers of different types of bacteria are then used to calculate a score and diagnose or rule out BV.

The problem is that this method is much more cumbersome and it usually requires sending your sample to a laboratory.

Finally, a third way of diagnosing BV is through molecular diagnostic techniques. These may be more expensive, but provide a better picture of the vaginal microbiome and are not affected by the subjective interpretation of your provider. Our Tiny Health vaginal test can find out all the different bacteria that are part of your vaginal microbiome.

There are major changes in your vaginal microbiome during BV

One of the characteristics of BV is the low numbers of Lactobacillus [12]. But there is one particular species that doesn’t seem to mind hanging out with the BV gang: Lactobacillus iners.

L. iners is in fact the most common Lactobacillus found in women with BV [13]. While this species is considered to be protective, apparently it doesn’t do a very good job compared to other lactobacilli. 

Vaginal communities dominated by L. iners (CST 3) may be less stable over time and often transition to BV-like communities.

One of the main disruptors in BV is Gardnerella vaginalis. This bacterium is often present in healthy vaginal communities, in low amounts [14]. Therefore, it is hard to say whether G. vaginalis is good or bad on its own.

But when its numbers go up, G. vaginalis displaces protective lactobacilli from the surface of the vaginal canal and secures its arrival by creating a biofilm [15]–[17]. A biofilm is like a fort that bacteria build to protect themselves and survive.

Two other relevant BV-associated bacteria are Prevotella bivia and Fannyhessea vaginae. They work together with G. vaginalis to make sure the biofilm stays strong, while also using it for shelter [15]–[18].

Other BV-associated bacteria that can also be present are Megasphaera, Dialister, Mobiluncus, Sneathia amnii, Sneathia sanguinegens, Porphyromonas, Aerococcus, UBA629 sp005465875 (also known as Candidatus Lachnocurva vaginae), Eggerthella, and Peptoniphilus [3], [19].

BV and its associated complications

Untreated BV may increase your risk of other vaginal, urinary, and sexually transmitted infections. It may also contribute to the development of inflammatory conditions that can threaten fertility or lead to pregnancy complications [20], [21].

Having BV may increase your risk of:

  • Pelvic inflammatory disease (PID). BV could make you about 3 times more likely to develop asymptomatic PID [22].
  • Infertility. High levels of F. vaginalis or A. vaginae could decrease your chances of getting pregnant after in vitro fertilization [23].
  • Recurrent implantation failure (RIF). Gardnerella, Fannyhessea, and Prevotella are high in women that experience RIF [24].
  • Preterm birth (PTB). Pregnant women diagnosed with BV are about twice more likely to experience PTB than healthy women [25], [26]. Also, having BV-associated bacteria such as Gardnerella, Prevotella, Fannyhessea, Sneathia, and Megasphaera may significantly increase the risk of PTB [27]–[35].
  • Viral sexually transmitted infections. Compared to women with a negative diagnosis, women diagnosed with BV are 1.6-2.6 times more likely to be infected with Human immunodeficiency virus (HIV), Human papillomavirus (HPV), or Herpes simplex virus 2 (HSV-2) [36]–[38].
  • Bacterial sexually transmitted infections. Compared to women with a negative diagnosis, women diagnosed with BV are 1.4-2.0 times more likely to get chlamydia, gonorrhea, or trichomoniasis [39], [40].

That’s a pretty long list of complications. The good news is that BV can be treated and there are things you can do to prevent it from coming back.

How to treat BV

BV is treated with antibiotics. If you suspect you may have BV, it’s very important to always get a diagnosis from your provider, never do antibiotics on your own. This is especially relevant if you are pregnant or breastfeeding. Some antibiotics for BV are sold over the counter and depending on your pregnancy trimester, they may be harmful for your baby. Your provider will help you choose the appropriate treatment.

These are the most common antibiotics used to treat BV:

  • Metronidazole (Flagyl, Metrogel-Vaginal, others). Comes as a pill to take orally or as a topical gel that you apply into your vagina. 
  • Clindamycin (Cleocin, Clindesse, others). Comes as a cream that you apply into your vagina. 
  • Tinidazole (Tindamax). Comes as a pill to take orally.

But BV-associated bacteria build such a strong biofilm that they are not easy to get rid of with antibiotics. 

A common problem is recurrent BV. This occurs when symptoms are alleviated by antibiotics but return soon after the treatment is finished, and this can happen more than one time [13], [14]. This may also happen because bacteria like F. vaginae can be resistant to antibiotics like metronidazole [41].

Another thing to consider is that, while antibiotics for BV are intended to eliminate BV-associated bacteria, they can also impact other beneficial bacteria like Lactobacillus. Because of this, an alternative treatment may be a good idea.

Alternative treatments for BV include:

  • Vaginal Lactobacillus probiotics. These can be used together with antibiotic treatment to increase success and to replenish Lactobacillus levels [42], [43]. You may also want to try probiotics alone, especially if you experience recurrent BV that doesn’t fully improve with antibiotic treatment. Some clinical trials in non-pregnant women have shown that probiotics can be effective for BV [44], [45].
  • Vaginal Lactobacillus suppositories. There are several studies showing that these are effective at restoring Lactobacillus levels, and may help reduce the episodes of BV [46]–[51]. If you’re pregnant, ask your provider before trying vaginal suppositories. Some brands may contain boric acid, which should not be used during pregnancy.
  • Vaginal vitamin C tablets. One of the characteristics of BV is a higher vaginal pH. Vaginal vitamin C tablets have a special formulation that slowly releases vitamin C in your vaginal canal. This helps lower the pH, which inhibits the growth of unfriendly species and supports beneficial Lactobacillus [52]–[56]. These tablets can be used along with a Lactobacillus probiotic to help with colonization. Some Lactobacillus suppositories contain vitamin C (also known as ascorbic acid).
  • Essential oil suppositories. If you are not pregnant, essential oil suppositories are another alternative that may help relieve BV symptoms. However, it’s important to mention that these have only been tested in laboratory experiments. If you choose to use them, always do so with the guidance of your provider. Dr. Aviva Romm also shares her go-to homemade suppository essential oil blend for addressing BV.

When shopping for a vaginal probiotic or suppository, you may want to look for high-performing and well-researched vaginal strains. When you take a Tiny Health vaginal test we recommend you products whose strains have been proven to be effective in clinical trials.

Things that may help you reduce the risk of BV

Luckily, there are things you can do to support your vaginal microbiome and reduce the risk of developing BV. This is especially important if you have a Community State Type (CST) 4, with low levels of Lactobacillus. Don’t know what type of vaginal community you have?

Our Tiny Health vaginal test can help you with that.

Here are some useful tips for vaginal health. You may already know these, but it’s always good to have a reminder. You can see some alternative interventions for CST4 or BV here.


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