Is Bacterial Vaginosis Actually an STI? What Research Shows

Vagina-havers, you may want to listen up. If you’ve ever had that pesky condition known as bacterial vaginosis, aka BV, we have some news for you: New research from Australia shows that BV might actually be a sexually transmitted infection, or STI.

This is a big deal because BV is a very common and super annoying health issue, affecting up to 29% of women worldwide. Untreated, it can lead to more serious things, like additional STIs and pelvic inflammatory disease, and it also has a tendency to recur months after successful treatment. BV can cause itching, discharge and odor, as well as a burning sensation when you pee.

But what does this news actually mean, and will it change the way doctors treat BV?  

Why is BV considered an STI now?

The new study found that BV is an STI by determining that women in the study whose male partners were also treated for BV ended up being way less likely to get BV again.

“To be honest, anyone who’s treated people with BV has always known there’s a male component to it. Many women will say they were fine until they had a specific partner,” says Zachary Pollack, MD, an OB-GYN at UW Medicine.

Hold up, you may be thinking. Why haven’t doctors made the connection before that BV is an STI? Is this just more of the same old sexism that women sometimes face in the doctor’s office?  

While sexism is very real — unfortunately, even in places like medical settings — there’s something else at work here that’s clear to doctors if not to patients.

“For something to be considered an STI, there has to be a known causative agent such as a virus or bacteria, like there is for STIs such as gonorrhea or HIV,” says Pollack. “There is no such causative agent known for BV. In fact, BV is more complex than a single infection — it’s a shift in the bacterial microbiome of the vagina.”  

Maybe you’ve heard of your gut microbiome, which consists of countless bacteria that help you digest your food. Well, there’s a similar colony of little microbes hanging out in your vagina — which may sound kind of gross, but they’re vital to keeping your vagina healthy. 

The causative agents for other STIs are well established. Chlamydia, for example — the most common STI worldwide — is caused by a single type of bacteria called Chlamydia trachomatis. HPV, aka human papillomavirus, is a viral infection that can lead to cervical cancer; in fact, there are 14 different variants of the virus that can put someone at higher risk.

There has not been the same level of research on whether or not bacteria causing BV can hide out in a penis or in sperm, the way infectious agents that cause known STIs do, but some research does suggest it’s possible. Research also suggests it’s possible that the penile microbiome could get altered by BV, too. (And yes, there is such a thing as a penile microbiome.) 

Can only women with male partners get BV?  

Historically, yes, cisgender women having penetrative, penis-in-vagina sex with cisgender men are the people most at risk for BV. The new study exclusively looked at women who were in monogamous relationships with male partners.  

More research needs to be done with women who are in relationships with other women, as well as with people who are transgender and non-binary. If you’re a woman in a relationship with another woman, there’s still a potential for things like sex toys to transmit BV if they aren’t properly cleaned.  

So, wait … does that mean, if you’re exclusively seeing a guy and you get BV, that he’s cheating on you? (Asking for a friend.) Not necessarily. It’s possible that there’s something going on with your totally trustworthy partner that somehow triggered BV in you; many women with a single long-term male partner still get BV. The only people who aren’t really at risk are people who aren’t having sex with anyone, Pollack says.  

Should doctors start treating male partners for BV?  

In the new Australian study, researchers looked at two groups of participants: women whose partners were treated for BV, and women whose partners were treated with only a placebo. The male partners who were treated took an oral antibiotic as well as using an antibiotic cream applied to the penis.  

Midway through the study, researchers actually had to halt work because preliminary data showed that women whose male partners were treated had a significant reduction in BV recurrence. It wouldn’t have been ethical to keep denying the other women that by withholding antibiotics for their partners.  

Previous research didn’t find such promising outcomes for treating male partners, but the new study tried a different approach.

“Until recently, there hasn’t been a good way to treat partners. The novel part of this new study was using oral antibiotics plus clindamycin cream on the penis, paired with the ability to detect changes at a more molecular level,” says Pollack.  

Does that mean all male partners of women with BV should be treated, too? It’s complicated. Men in the study did get treated, of course. Some experienced side effects from the antibiotics, while others didn’t. Would men in the real world do the same?  

“There are people who don’t complete their antibiotics for a condition they have symptoms for, so would men actually take the medication if they aren’t suffering?” Pollack says. “The hope is that more research will show that treating partners is a beneficial thing to do.”

Treating men might be especially worth considering when a woman has one longer-term male partner, since her getting recurring BV would indicate it is indeed related to sex with that guy specifically.  

How to deal with BV, even if it recurs  

There are two main treatments for BV: oral antibiotics, which are for shorter-term use, and antibiotic creams, which are used for people who get BV often. There are additional treatment options such as boric acid, too.

Chronic or recurring BV is defined as getting at least three infections within the same year. Researchers are still looking into how to make treatment more effective.  

“There is an emerging thought process that BV creates a biofilm in the vagina that makes it hard for us to get these drugs to work, and there is some emerging evidence that using boric acid helps increase the efficacy of the antibiotics,” Pollack says.

If you think you have BV, the most important thing to do is make an appointment with your doctor. Don’t try unregulated probiotics or douching products, as they can make the problem worse and put you at risk for other STIs. And don’t assume it’s BV and you need antibiotics.  

“Studies have shown that practitioners are wrong half the time if they base diagnosis on symptoms alone, so even if you’ve had BV before, getting the right diagnosis is important,” Pollack says.

There are two main diagnostic tests, both of which include a vaginal swab: one test involves interpreting results under a microscope, and the other is a nucleic acid amplification test (NAAT).  

The best way to prevent BV is to use condoms. But it’s also important to note that getting BV does not mean you did anything wrong — you’re not unhygienic or eating the wrong foods or whatever else the internet wants to convince you of.  

Hopefully, the new research on BV will help make treatment even more effective in the near future. 

This article has been updated with more accurate information about the risk of women having sex with women getting bacterial vaginosis.