Trial finds male-partner antibiotic treatment cuts bacterial vaginosis recurrence.
The results of a randomized controlled trial conducted in Australia indicate that the addition of antibiotic treatment for male partners of women who have bacterial vaginosis (BV) significantly reduces recurrence of the infection, researchers reported yesterday in the New England Journal of Medicine.
The trial, in fact, was stopped early because BV recurrence was cut in half among women who were taking first-line antibiotics and whose partners also received topical and oral antibiotic treatment, compared with the control group, in which only the women received first-line antibiotic treatment.
BV is a disruption of the vaginal microbiome that affects nearly one in three women worldwide. More than 50% of women have recurrence within 3 months of antibiotic treatment, and the risk of recurrence is higher in women who report sex with a regular partner than in those without a regular partner. Side effects include adverse birth outcomes, increased risk of sexually transmitted infections (STIs), and pelvic inflammatory disease.
Trial investigators say the findings suggest that reinfection from male sexual partners contributes to BV recurrence and supports the idea that it should be considered an STI.
"This successful intervention is relatively cheap and short and has the potential for the first time to not only improve BV cure for women, but opens up exciting new opportunities for BV prevention, and prevention of the serious complications associated with BV," co-lead investigator Catriona Bradshaw, PhD, of Monash University and the Melbourne Sexual Health Centre, said in a university press release.
Male partner treatment significantly reduces BV recurrence
The open-label trial, conducted from April 2019 through November 2023, enrolled couples in which a women had symptoms of BV and had a regular male partner for at least 8 weeks before enrolment. The couples were randomly assigned in a 1:1 ratio to the partner-treatment group or the control group. Of the 357 couples assessed for eligibility, 164 underwent randomization, with 81 assigned to the partner-treatment group and 83 to the control group.
In the partner-treatment group, the women received first-line recommended antibiotics for a week, and their male partners received an oral and topical antibiotic (400 milligram metronidazole tablets and 2% clindamycin cream, both twice daily for 7 days). In the control group, only the women received antibiotics, which is the standard. The primary outcome was recurrence of BV within 12 weeks.
This successful intervention is relatively cheap and short and has the potential for the first time to not only improve BV cure for women, but opens up exciting new opportunities for BV prevention, and prevention of the serious complications associated with BV.
The trial was stopped by the data safety and monitoring board after 150 couples had completed the 12-week follow-up. Recurrence of BV occurred in 24 of 69 women (35%) in the partner-treatment group (recurrence rate, 1.6 per person-year; 95% confidence interval [CI], 1.1 to 2.4) compared with 43 of 68 women (63%) in the control group (recurrence rate, 4.2 per person-year; 95% CI, 3.2 to 5.7). This corresponded to an absolute risk difference of –2.6 recurrences per person-year (95% CI, –4.0 to –1.2) and a 63% lower risk of recurrence (hazard ratio, 0.37; 95% CI, 0.22 to 0.61) among women in the partner-treatment group.
Secondary and sensitivity analyses supported the findings of the primary analysis. Data on adverse events showed that 46% of male partners who received treatment reported nausea, headache, and metallic taste.
Paradigm shift
To date, the specific bacteria that cause BV have been unclear, and these results don't answer that question. Bradshaw and her colleagues note that while studies have shown men may harbor bacteria associated with BV on their penis and that the penile microbiota is predictive of a woman's risk of BV, previous trials of male-partner treatment have not found increased incidence of cure in their female partners. But that could be because men in those trials received only oral antibiotics.
"This was interpreted as evidence against sexual transmission," Bradshaw said. "However, these studies had design limitations, and none used a combination of oral and topical antibiotics to adequately clear BV bacteria in men, especially from the penile-skin site."
In an accompanying editorial, infectious disease experts from the University of Alabama at Birmingham and Wayne State University say the results represent a "paradigm shift" for how women with BV are treated. Clinicians will have to educate their patients on the role of sexual transmission, and male partners will need to accept their role in transmission and be willing to take both oral and topical medication.
They also suggest similar trials are needed in more diverse populations, since racial and ethnic disparities in BV have been well-documented, and in women without regular male partners.
"Despite these limitations, this trial provides data critical to educating clinicians and patients about the role of sexual transmission of bacterial vaginosis–associated bacteria and the benefit of male-partner treatment," Christina Muzny, MD, MSPH, and Jack Sobel, MD, wrote. "It is time to start the conversation."
Written by Chris Dall, MA