March 12 (UPI) -- Health experts say an Australian study linking sexual activity to an infection that 1 in 3 U.S. women contract has provided a new tool to prevent recurrences, as well as find a cure.
In the wake of what's being hailed as a landmark study, experts from around the world told UPI this week that they've gained a key new insight into the nature of bacterial vaginosis, although they also cautioned that finding a cure for all women will require more work.
BV is caused by a disruption in the bacteria present in the vagina. In BV, the "good" or "healthy" bacteria called lactobacilli are replaced with a group of "bad" or "non-optimal' bacteria, causing symptoms such as discharge and odor.
While most women with BV do not experience complications, it can increase the risk of developing pelvic inflammatory disease, getting a sexually transmitted infection and experiencing pregnancy complications, such as preterm birth.
BV has been treated since the 1980s with oral or vaginal antibiotics. However, half of women experience recurrences within three to six months of completing antibiotics. Women in monogamous relationships with a regular sexual partner are even more likely to get BV again after antibiotics.
Until now, BV was not widely considered to be sexually transmitted, despite evidence that showed a possible connection. But the study published last week found a strong linkage that promises to "forever change the way BV is treated," according to its authors, clinician scientist Catriona Bradshaw and senior research fellow Lenka Vodstrcil, of the Melbourne Sexual Health Center and Monash University.
The study was published Thursday in the New England Journal of Medicine. In it, they determined that BV is indeed sexually transmitted and reported that when male partners took oral and topical antimicrobial therapies, those actions -- combined with the usual antibiotic treatment for women -- resulted in significantly lower recurrence rates.
They found a 35% rate of BV recurrence among couples in which both partners were treated, compared with a 63% rate of recurrence among those in a standard-care control group after 12 weeks.
They undertook the effort after earlier studies showed that men may carry bacteria associated with BV in their urethras, and that microbes found in the penis can predict a woman's risk of contracting the condition.
Past trials testing that connection didn't show an increased incidence of cure, which was interpreted as evidence against sexual transmission. However, most of those trials had "substantive limitations," Bradshaw and Vodstrci argued, including limited statistical power among other drawbacks.
Their findings, based on 150 couples in monogamous relationships from April 2019 through November 2023, have been hailed as a breakthrough in efforts to find a cure for BV, which have been hampered by an incomplete understanding of its origins and development.
Bradshaw told UPI in emailed comments the study proved for the first time that "sexual transmission [of BV] is occurring and that reinfection is the dominant driver of recurrence."
"The fact that concurrent treatment of male partners -- using an oral antibiotic to target urethral BV bacteria and a topical antibiotic cream to target the penile skin BV bacteria -- very significantly reduces BV recurrence for women confirms reinfection of women is occurring.
"This is exactly what we see with STIs like chlamydia. If you don't treat the male partner, women get chlamydia back again," she said.
She noted that the women in the trial were "highly motivated with highly recurrent BV." Some had strong risk factors for recurrence, such as uncircumcised male partners and an IUD birth control device.
"Recurrence rates in these women are typically 60% to 80%, and this intervention more than halved recurrence rates," Bradshaw said.
She added: "So, does this change the way BV is forever treated? Yes, it does. It is a simple strategy that is highly relevant to women with an ongoing male partner. Will it cure all women? No, but it offers a very significant proportion of these women the prospect of a cure, which they have never had before."
The trial, Bradshaw added, also is "a major paradigm shift in knowledge and clinical practice that very importantly helps us get far closer to curing all women, as it identifies a group of women who may be experiencing BV persistence due to female factors, such as an IUD."
Reaction from women's health experts and researchers contacted by UPI was uniformly positive, although many cited the need for continuing study.
Rebecca Brotman, an epidemiology and public health professor and researcher at the University of Maryland's Center for Advanced Microbiome Research & Innovation, said the Australian trial showed that "If you have BV and are in a heterosexual, monogamous relationship ... you are more likely to achieve a cure and prevent recurrence if both you and your partner receive simultaneous treatment."
While it marks "a significant advancement in BV treatment, further research is necessary to confirm the findings across diverse populations and for a longer duration of follow-up," Brotman added.
"The trial proved a significant reduction in BV recurrences with male partner treatment, but 35% still recurred in the partner-treatment group. I hope this trial paves the way for future studies to further explore the underlying causes, prevention strategies and improved treatment options for BV," she said.
Brotman also warned that classifying BV as a sexually transmitted infection needs to be approached carefully, "as it could unintentionally reinforce stigma associated with sexual activity and BV. Further research is needed to clarify these relationships and their implications for prevention."
Dr. Kameelah Phillips, an obstetrician-gynecologist and founder of Calla Women's Health in New York City, said the study "reinforces what many of us -- both doctors and patients -- have long suspected: Sexual intercourse in heterosexual couples is a significant risk factor for recurrent BV, and treating both partners in monogamous relationships may be an important consideration."
While it represents "an exciting step forward in women's health," Phillips said it's important to acknowledge "the study's limitations. With a sample size of only 150 couples, these findings will need validation in larger and more diverse populations before they can influence clinical guidelines.
"Still, for the millions of women who struggle with recurrent BV, this research highlights the need for fresh, innovative approaches to treatment," she said. "They deserve more than temporary fixes -- they deserve solutions that truly address the root of the problem."
Dr. Caroline Mitchell, director of the Vulvovaginal Disorders Program at Massachusetts General Hospital in Boston, told UPI the latest findings "offer us another, important tool for helping prevent recurrence of BV in some patients. Since treatment options in the field haven't substantively changed since 1982, this is a huge win for women."
In her practice, Mitchell said, she see patients for whom BV "seems very sexually facilitated," but for others it is not the case at all, "so I don't think this is universal. BV isn't like chlamydia. There isn't always that direct connection -- especially for recurrent BV.
"However, BV does seem to be sexually facilitated -- and the results of this study suggest that microbes on the penis likely play a role in at least some cases," she added.
"For people with highly recurrent BV, I do think that there may be some passing back and forth of BV-associated bacteria between sexual partners, and that treating both people ... will be necessary to clear those organisms."