What is the best treatment approach for a male patient who repeatedly transmits bacterial vaginosis to his female partner?

Treatment of Male Partners in Recurrent Bacterial Vaginosis

For males whose female partners experience recurrent bacterial vaginosis, treat the male partner with metronidazole 400 mg orally twice daily for 7 days PLUS clindamycin 2% cream applied to penile skin twice daily for 7 days, while simultaneously treating the female partner with standard first-line therapy. 1, 2

Evidence Supporting Partner Treatment

The traditional CDC stance that treating male partners does not prevent BV recurrence 3, 4 has been overturned by a landmark 2025 randomized controlled trial that demonstrated clear benefit:

• The 2025 StepUp trial showed that combined treatment of both partners reduced BV recurrence from 63% to 35% within 12 weeks (absolute risk reduction of 2.6 recurrences per person-year, P<0.001). 2
• This trial was stopped early by the data safety monitoring board because treating women alone was clearly inferior to treating both partners. 2
• The evidence strongly suggests sexual exchange of BV-associated organisms between partners, supporting the rationale for partner treatment. 2

Specific Treatment Protocol

For the Male Partner:

• Metronidazole 400 mg orally twice daily for 7 days 1, 2
• AND clindamycin 2% cream applied to penile skin twice daily for 7 days 1, 2

For the Female Partner:

• Standard first-line therapy: metronidazole 500 mg orally twice daily for 7 days 3, 5, 6
• Alternative options include metronidazole gel 0.75% intravaginally or clindamycin preparations 3

Critical Patient Instructions

Both partners must adhere to these precautions:

• Avoid all alcohol during metronidazole treatment and for 24 hours after completion to prevent disulfiram-like reactions (nausea, vomiting, flushing). 3, 1
• Refrain from unprotected intercourse for at least 14 days to allow treatment to take effect. 1
• Complete the full 7-day course even if symptoms resolve earlier. 1, 2

Expected Adverse Effects in Treated Males

Common side effects include:

• Nausea 2
• Headache 2
• Metallic taste 2

These are generally mild and self-limited. 2

When Partner Treatment Is Indicated

Partner treatment should be considered specifically for:

• Recurrent BV cases (defined as multiple episodes despite appropriate treatment of the female partner). 1, 5
• Couples in monogamous relationships where reinfection from the male partner is suspected. 2
• Women who have experienced treatment failure with standard therapy alone. 5

Important Clinical Caveats

• This represents a paradigm shift: Six older randomized trials showed no benefit to partner treatment 1, but the 2025 trial used a more comprehensive approach (combined oral and topical therapy) that proved effective. 2
• Partner treatment is not recommended for initial BV episodes—reserve this approach for recurrent cases. 1
• No routine follow-up is needed for asymptomatic male partners, but women should return if symptoms persist or recur. 1
• Recurrence rates remain high (50-80% within one year) even with optimal treatment, possibly due to biofilm formation or poor adherence. 3, 5, 7

Alternative Approach for Recurrent BV in Women

If partner treatment fails or is not feasible:

• Extended metronidazole 500 mg orally twice daily for 10-14 days 5, 6
• If ineffective, metronidazole gel 0.75% for 10 days, then twice weekly for 3-6 months 5, 6
• Consider secnidazole as a single-dose alternative, though evidence is limited for recurrent cases. 5