Can Bacterial Vaginosis Be Transmitted to Men?
No, bacterial vaginosis (BV) is not traditionally considered a sexually transmitted disease that causes symptomatic infection in men, though recent evidence demonstrates that BV-associated bacteria are sexually exchanged between partners and colonize the male genitalia. 1
Understanding BV Transmission Dynamics
What Happens During Sexual Contact
BV-associated bacteria colonize the penis but do not cause symptomatic disease in men. 1 Male partners remain asymptomatic even when carrying BV-associated organisms on penile skin and in the urethra. 2, 3
Sexual exchange of BV-associated bacteria between partners is well-documented. 4, 5 The penile skin and urethral microbiota of male partners of women with BV shows significantly higher similarity to their female partner's vaginal microbiota compared to non-partner women with BV. 5
Specific BV-associated bacterial species (including Mobiluncus and Dialister) are concordant between women with BV and their male partners. 5, 6 This bacterial exchange occurs during intercourse but does not produce infection or symptoms in men.
Clinical Implications for Men
Men do not require evaluation or testing for BV-associated bacteria. 1 There are no diagnostic criteria or symptomatic manifestations of BV in males.
Women who have never been sexually active rarely develop BV, suggesting sexual activity plays a role in transmission dynamics. 1, 2 However, BV results from disruption of normal vaginal flora rather than acquisition of a single transmissible pathogen.
Partner Treatment Considerations
Current Guideline Recommendations
- CDC guidelines state that routine treatment of male sex partners is not recommended because historically it has not influenced the woman's response to therapy or affected relapse/recurrence rates. 1, 7, 2, 3 The principal goal of BV therapy is to relieve vaginal symptoms in the affected woman, not to prevent transmission. 1, 3
Emerging Evidence on Partner Treatment
A 2025 randomized controlled trial from Australia demonstrated that treating male partners with combined oral metronidazole (400 mg twice daily for 7 days) plus topical 2% clindamycin cream (applied to penile skin twice daily for 7 days) reduced BV recurrence in female partners from 63% to 35% over 12 weeks. 4 This represents an absolute risk reduction of 2.6 recurrences per person-year.
This single high-quality trial contradicts decades of prior studies showing no benefit from partner treatment. 4, 8 The key difference was the combination of oral and topical antimicrobial therapy targeting penile colonization, rather than oral treatment alone.
Clinical Application Caveat
Current CDC guidelines have not yet been updated to reflect this new 2025 evidence. 2, 8 More research is needed to determine if these results are applicable to broader populations beyond the Australian cohort studied. 8
For women with recurrent BV despite standard treatment, consider discussing partner treatment as an option using the regimen from the 2025 trial: metronidazole 400 mg orally twice daily for 7 days plus 2% clindamycin cream applied to penile skin twice daily for 7 days. 7, 2, 4
Important Safety Information for Partner Treatment
Men receiving metronidazole must avoid all alcohol during treatment and for 24 hours after completion to prevent disulfiram-like reactions. 7, 2, 3 This includes alcohol in medications, mouthwash, and food products.
Clindamycin cream is oil-based and can weaken latex condoms and diaphragms for up to 5 days after treatment. 7, 3 Couples should use alternative contraception during this period if needed.
Adverse effects in treated men include nausea, headache, and metallic taste. 4
Key Clinical Pitfalls
Do not confuse BV transmission dynamics with classic sexually transmitted infections. 1 BV represents an ecological disruption of vaginal flora rather than infection with a single pathogen, though sexual exchange of bacteria clearly occurs.
Do not use metronidazole gel for male partners. 2 The successful regimen used combination oral and topical treatment specifically targeting penile colonization.
Do not treat male partners based solely on older guidelines without discussing the limitations of current evidence and the emerging data. 8 Shared decision-making is appropriate given the evolving understanding of BV transmission.