This common infection that affects millions of women is actually an STI
For decades, bacterial vaginosis has been treated as a women’s health issue—but new research suggests treating male partners could dramatically cut recurrence rates.
For decades, bacterial vaginosis (BV) has been treated as a frustrating but routine infection—one that afflicts nearly a third of women in the U.S. and often comes back again and again for more than half of patients. But what if the reason for these relentless recurrences isn’t just a quirk of the vaginal microbiome?
A groundbreaking new study suggests BV isn’t just an imbalance—it’s sexually transmitted. And the key to stopping it may not lie in treating women alone but in treating their male partners as well.
“One dominant risk factor… in our clinical studies was a regular partner,” says Catriona Bradshaw, an author of the study and a clinician at Melbourne Sexual Health Centre at Monash University. “[It] kept popping out and just smacking us between the eyes, and we got to a point where we thought ‘we just have to do a partner treatment trial.’”
Is bacterial vaginosis sexually transmitted?
BV occurs when the perfect storm of bacteria combines in the vagina. Unlike typical sexually transmitted infections (STIs), no single pathogen is responsible. But, it has long been suspected that these bacteria can be sexually transmitted.
“We’ve had evidence for many years that bacterial vaginosis might be a sexually transmitted infection, based on data that includes increased risk of bacterial vaginosis with increasing number of sexual partners, increased risk with sex without a condom, and other evidence,” says David Fredricks, a clinician and microbiologist at the University of Washington. “Although this hypothesis has been out there for many decades, some limited studies of male partner treatment to eradicate BV associated bacteria have not met with success.”
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In fact, BV has long been treated as an STI in same-sex female partners. “There’s been studies since the 80s, and lesbian monogamous couples had astonishingly high concordance for BV,” Bradshaw says. “We’re talking at 80 percent.”
A study she worked on found that lesbian couples had nearly a 20 percent higher rate of BV than the general population of Australia. And, when monogamous same-sex couples entered the study without BV, they also ended it that way, she says. “It’s clearly being transmitted between women. So why on earth wouldn’t it be transmitted between men and women?” she says.
A new approach to treatment
To test that idea, Bradshaw and epidemiologist Lenka Vodstrcil studied opposite-sex monogamous couples in which the woman had BV. Unlike past studies, which had failed to show a clear benefit, their research introduced a key difference: In addition to taking oral antibiotics, men also applied a topical antibiotic, clindamycin, directly to the penis.
After seven days of treatment and regular testing over 12 weeks, the difference between couples in the treatment and the control groups was striking. The number of women who experienced recurrent BV when their partners were treated was nearly half the amount of women whose partners hadn’t, providing strong evidence that BV might be sexually transmitted.
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The difference was so significant that a data and safety monitoring board advised the researchers to stop the trial early. “I think that was obviously really exciting at that point,” says Vodstrcil. “It meant that we were really showing a strong effect of male partner treatment.” The study also showed that couples with an uncircumcised partner saw higher rates of recurrence and that the more partners stuck to their treatment regimen, the better the results.
Can this stop BV from reoccurring?
More research will need to be done on what the best treatment course for men is in these instances, but knowing that treatment can help their female partners is a big step. “This [study] kind of confirmed what many of us have suspected in the past,” Fredricks says.
For now, the standard treatment of BV is often short-term and always focused on treating the vagina. But even after a round of antibiotics, over half of women experience a recurrence of the infection within three months. In those cases, doctors often use an extended period of antibiotic gels in suppressive therapy.
The process can last upwards of six months, depending on the patient, says Traci Kurtzer, clinical assistant professor of obstetrics and gynecology at Northwestern Medicine. “[BV] is [an infection] that is so commonly recurrent for them, and it gets frustrating. And of course, it becomes frustrating for the medical professional taking care of them, who feels…helpless,” she adds.
Although there are certainly still a lot of unknowns about BV, this study may quickly change treatment for monogamous opposite-sex couples. “My institution, at the University of Washington, for instance, they’re already talking about changing policy,” says Fredericks.
But for this to work, it will take buy-in from male partners and a commitment to treatment by both parties. Still, researchers are optimistic. “There’s no symptoms in men, so it is harder for them to feel like they’re part of the problem,” Vodstrcil says. “But we really emphasize that they can now be part of the solution.”
