Male-partner treatment to prevent recurrence of bacterial vaginosis
Bacterial vaginosis is due to an overgrowth of vaginal microbes and affects 30 percent of women worldwide. The first-line treatments for this infection are metronidazole and clindamycin. However, more than half of women will experience a recurrence within three months of treatment. Epidemiologic and microbiologic data indicate that bacterial vaginosis has the profile of a sexually transmitted infection (STI). For example, incident bacterial vaginosis has an incubation period similar to that of other bacterial STIs and is associated with new sexual partners. Studies have shown that men may have bacterial species in their distal urethra and subpreputial space that are associated with bacterial vaginosis and that this is predictive of a woman’s risk of recurrent bacterial vaginosis. However, previous studies of male-partner treatment for such bacterial species did not show an increased incidence of cure or recurrence of bacterial vaginosis in women, which was interpreted as indicating a lack of sexual transmission. Of note, most of these studies had substantive limitations, including limited statistical power, lack of assessment of adherence, and use of single-dose regimens of oral antimicrobial agents alone—without topical treatment. The authors conducted a randomized controlled trial, called StepUp, to determine if concurrent oral and topical antimicrobial treatment of male partners of women with bacterial vaginosis reduced recurrence of the infection compared with the standard of care of treating only the women. The open-label randomized controlled trial involved women with bacterial vaginosis and their monogamous male partners of at least eight weeks. In the partner-treatment group, the women received first-line antimicrobial agents and their male partners received both oral and topical antimicrobial treatment—metronidazole 400-mg tablets taken twice daily for seven days and two percent clindamycin cream applied to penile skin twice daily for seven days. In the standard-of-care control group, the women received first-line antimicrobial treatment and the men received no treatment. The investigators recorded a primary outcome of recurrence of bacterial vaginosis within 12 weeks. Eighty-one couples were assigned to the partner-treatment group, and 83 couples were assigned to the control group. Of interest, after 150 couples completed the 12-week follow-up period, the trial was discontinued because the women-only treatment group showed inferior results when compared with the group in which both the female and male partners were treated. Recurrence of bacterial vaginosis occurred in 35 percent (24 of 69) of women in the partner-treatment group (recurrence rate, 1.6 per person-year; 95 percent confidence interval [CI], 1.1–2.4) and in 63 percent (43 of 68) of women in the control group (recurrence rate, 4.2 per person-year; 95 percent CI, 3.2–5.7). This resulted in an absolute risk difference of -2.6 recurrences per person-year (95 percent CI, -4.0 to -1.2). The study recorded adverse events in treated men, including nausea, headache, and metallic taste from the oral antimicrobial agents. In conclusion, the trial showed that combined oral and topical antimicrobial therapy for male partners of women treated for bacterial vaginosis resulted in lower recurrence among those women within 12 weeks than among women receiving the standard of care. The authors noted that unlike previous trials of male-partner treatment, which used only oral antimicrobial therapy, this trial also targeted associated organisms in the penile urethra and penile skin with topical medication. Recurrence rates were found to be lowest in women whose male partners adhered to the antimicrobial therapy protocol. Sensitivity analyses demonstrated that the lowest recurrence rate (1.3 per person-year) was among the female partners of men who reported 100 percent adherence to the treatment schedule.
Vodstrcil LA, Plummer EL, Fairley CK, et al. Male-partner treatment to prevent recurrence of bacterial vaginosis. N Engl J Med. 2025;392:947–957.
Correspondence: Dr. Lenka Vodstrcil at lenka.vodstrcil@monash.edu or Dr. Catriona Bradshaw at catriona.bradshaw@monash.edu