A Randomized Trial of Male Partner Treatment with Oral Metronidazole and Topical Clindamycin or Topical Clindamycin Alone for Prevention of Recurrent Bacterial Vaginosis

About This Grant

Bacterial vaginosis (BV), a common disorder of the vaginal microbiota which can result in vaginal odor and discharge, affects nearly 30% of women in the United States (US) and is associated with increased risk of sexually transmitted infection acquisition and adverse obstetric outcomes. Available treatments have limited efficacy; more than half of patients experience recurrence within 12 weeks of antibiotics. Although it has long been speculated that BV recurrence may relate to sexual transmission of bacteria from asymptomatically colonized male partners, there are no current recommendations to treat male partners of women with BV, mainly because seven previous male partner treatment (MPT) trials using oral antibiotics had failed. However, recently, a new randomized open label trial of MPT with oral metronidazole plus topical clindamycin conducted in Australia and published in March 2025, (the “StepUp” trial), showed a significant decrease in BV recurrence in the female partner (63% recurrence in the control arm vs. 35% in the MPT arm) over 12 weeks. While these results are exciting, additional research is urgently needed before broad recommendations for MPT can be made for US populations. There is uncertainty regarding whether the intervention would be equally efficacious in the US given important differences, including circumcision status, between US and the Australian study populations. Moreover, since the male partner must take on risk of MPT without direct benefit to themselves, a non-systemic antibiotic option would be preferred. One key unanswered question is whether topical clindamycin alone could be an effective MPT approach-which is plausible (though not certain) because the most notable difference in treatment regimen between StepUp and the previous failed trials was the addition of this topical antibiotic. We therefore propose a US-based, three-arm, parallel-group, open-label (investigator-masked), Phase III randomized controlled trial to enroll women of reproductive age with symptomatic BV and their monogamous male partners. The women will be treated with standard BV antibiotics while their male partners will be randomized to no treatment, topical clindamycin alone, or oral metronidazole plus topical clindamycin. Participants will be followed over 12 weeks to 1. Compare efficacy of MPT with topical clindamycin versus no MPT in reducing BV recurrence in the BV patient and 2. Compare efficacy of MPT with oral metronidazole plus topical clindamycin versus no MPT in reducing BV recurrence in the BV patient over 12 weeks after treatment. We will additionally collect longitudinal samples from women and their male partners which can be leveraged in the future to elucidate biologic mechanisms underlying BV recurrence and guide additional treatment approaches. The proposed MPT trial, if successful, could change clinical practice for thousands of BV patients in the US. Moreover, it will provide needed evidence on which to base national guidelines around MPT, and ultimately improve BV treatments to benefit reproductive and obstetric health in the US.