What is the treatment for a male partner to prevent the transmission of bacteria that could contribute to Bacterial Vaginosis (BV) in a female partner?

Male Partner Treatment for Bacterial Vaginosis

Direct Recommendation

Treat male partners of women with bacterial vaginosis using combined oral metronidazole 400 mg twice daily PLUS topical 2% clindamycin cream applied to the glans penis and upper shaft (under foreskin if uncircumcised) twice daily for 7 days. This approach reduces BV recurrence from 63% to 35% within 12 weeks compared to treating the woman alone. 1

Evidence-Based Rationale

The Paradigm Has Shifted

The traditional approach of not treating male partners was based on older CDC guidelines from 1993, which stated that male partner treatment did not influence recurrence rates. 2 However, a landmark 2025 randomized controlled trial (StepUp trial) published in the New England Journal of Medicine definitively overturned this recommendation. 1

Key Trial Findings

The StepUp trial was stopped early by the data safety monitoring board because treating women alone was clearly inferior to treating both partners: 1

• Recurrence rate with partner treatment: 35% (1.6 per person-year)
• Recurrence rate without partner treatment: 63% (4.2 per person-year)
• Absolute risk reduction: 2.6 recurrences per person-year (P<0.001)

This represents a 44% relative reduction in BV recurrence when male partners receive treatment. 1

Why Partner Treatment Works

Male partners carry BV-associated bacteria (Gardnerella vaginalis, Mobiluncus species, anaerobes) and can reinfect female partners through sexual contact. 3, 1 While men remain asymptomatic, they serve as a reservoir for bacterial transmission. 2, 4

Treatment Protocol

For the Female Partner

• Metronidazole 500 mg orally twice daily for 7 days 2
• Alternative: Clindamycin 2% vaginal cream for 7 days if metronidazole contraindicated 2

For the Male Partner (NEW EVIDENCE-BASED APPROACH)

• Metronidazole 400 mg tablets orally twice daily for 7 days 1
• PLUS 2% clindamycin cream applied topically to penile skin (glans and upper shaft, under foreskin if uncircumcised) twice daily for 7 days 1

Critical Instructions for Both Partners

• Avoid alcohol during metronidazole treatment and for 24 hours after completion to prevent disulfiram-like reactions 2, 4
• Refrain from unprotected intercourse for at least 14 days to allow treatment to take effect 5

Nuances in the Evidence

Conflicting Studies

A 2021 trial using oral metronidazole alone for male partners showed no significant benefit in the overall population. 5 However, this study found that women whose male partners adhered to medication had significantly lower treatment failure rates (adjusted relative risk 0.85, P=0.035). 5 This suggests that:

1. Adherence is critical for success
2. Oral therapy alone may be insufficient
3. The combination of oral + topical therapy (as used in the 2025 StepUp trial) is superior

An older 1989 study showed benefit from single-dose partner treatment, but used less rigorous methodology and lower doses. 6

Why the Combined Approach Is Superior

The StepUp trial's success likely stems from: 1

• Dual route of administration (oral + topical) targeting both systemic carriage and local penile colonization
• Extended 7-day duration rather than single-dose therapy
• Combination of two antimicrobials (metronidazole + clindamycin) with different mechanisms

Common Pitfalls and How to Avoid Them

Pitfall 1: Relying on Outdated Guidelines

Avoid: Following 1993 CDC recommendations that discourage partner treatment 2
Do: Use the 2025 New England Journal of Medicine evidence showing clear benefit 1

Pitfall 2: Treating Male Partners with Oral Therapy Alone

Avoid: Prescribing only oral metronidazole for male partners 5
Do: Use the combined oral + topical regimen proven effective 1

Pitfall 3: Poor Adherence

Avoid: Failing to emphasize the importance of completing the full 7-day course 5
Do: Counsel both partners on adherence, as this directly correlates with treatment success 5

Pitfall 4: Inadequate Alcohol Counseling

Avoid: Neglecting to warn about alcohol-metronidazole interactions 2
Do: Explicitly instruct patients to avoid all alcohol during and 24 hours after treatment 2, 4

Pitfall 5: Allowing Unprotected Intercourse During Treatment

Avoid: Permitting sexual contact during the treatment period 5
Do: Advise abstinence or barrier protection for at least 14 days 5

Expected Adverse Effects in Male Partners

Men receiving combined therapy may experience: 1

• Nausea
• Headache
• Metallic taste
• Mild gastrointestinal upset

These effects are generally mild and self-limited. 1

Follow-Up Considerations

• Women should be reassessed at 3 weeks and 12 weeks to confirm cure 1
• No routine follow-up is needed for asymptomatic male partners 2
• If BV recurs despite partner treatment, consider biofilm disruption strategies or extended suppressive therapy 7