What is the treatment for bacterial vaginosis?

Treatment of Bacterial Vaginosis

For nonpregnant women with bacterial vaginosis, oral metronidazole 500 mg twice daily for 7 days is the preferred first-line treatment with the highest efficacy (95% cure rate). 1, 2

First-Line Treatment Options for Nonpregnant Women

The CDC recommends three equally effective first-line regimens:

• Oral metronidazole 500 mg twice daily for 7 days achieves cure rates up to 95% and is the most studied regimen 1, 2
• Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days provides equal efficacy to oral therapy but with fewer systemic side effects (mean peak serum concentrations <2% of oral doses) 3, 1, 2
• Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days demonstrates comparable cure rates (82% at 4 weeks) to oral metronidazole 3, 2

The intravaginal preparations are particularly useful for patients who experience gastrointestinal side effects or unpleasant taste with oral metronidazole. 3

Alternative Treatment Options

When first-line regimens cannot be used or compliance is a concern:

• Oral metronidazole 2g as a single dose has lower efficacy (84% cure rate) compared to the 7-day regimen but may be appropriate when adherence is questionable 3, 1, 2
• Oral clindamycin 300 mg twice daily for 7 days is an alternative when metronidazole cannot be used 3, 1, 2
• Tinidazole 2g once daily for 2 days or 1g once daily for 5 days demonstrated therapeutic cure rates of 27.4% and 36.8% respectively in FDA trials (though these rates appear lower due to stricter cure criteria requiring resolution of all 4 Amsel's criteria plus Nugent score <4) 4

Treatment in Pregnancy

All symptomatic pregnant women should be tested and treated for BV to prevent adverse pregnancy outcomes including preterm delivery. 1, 2, 5

High-Risk Pregnant Women (History of Preterm Delivery)

• Metronidazole 250 mg orally three times daily for 7 days is the recommended regimen, with screening and treatment conducted in the earliest part of the second trimester 1, 2, 5, 6
• Systemic therapy is preferred over topical therapy to treat possible subclinical upper genital tract infections 5, 6
• Treatment may reduce the risk of prematurity in this population 1, 2, 5

Low-Risk Pregnant Women (No Prior Preterm Birth)

• Metronidazole 250 mg orally three times daily for 7 days for symptomatic disease 6
• Alternative: Clindamycin 300 mg orally twice daily for 7 days 5

Important Pregnancy Considerations

• Clindamycin vaginal cream is NOT recommended during pregnancy due to increased risk of preterm deliveries demonstrated in randomized trials 5
• Multiple studies and meta-analyses have not demonstrated teratogenic or mutagenic effects with metronidazole use during pregnancy, despite animal studies using extremely high doses suggesting potential concerns 3, 5
• Metronidazole is considered compatible with breastfeeding, as only small amounts are excreted in breast milk 2

Special Populations and Situations

Patients with Metronidazole Allergy or Intolerance

• Clindamycin cream 2% intravaginally or oral clindamycin 300 mg twice daily for 7 days is preferred 1, 2, 5
• Patients allergic to oral metronidazole should NOT use metronidazole vaginally 2, 5

HIV-Infected Patients

• Patients with HIV and BV should receive the same treatment regimens as persons without HIV 2

Before Surgical Procedures

• Screen and treat women with BV before surgical abortion or hysterectomy due to substantially increased risk of postoperative infectious complications including PID 3, 2, 5
• Treatment with metronidazole has been shown to substantially reduce post-abortion PID in randomized controlled trials 3, 5

Critical Treatment Precautions

Alcohol Avoidance

• Patients using metronidazole or tinidazole must avoid alcohol during treatment and for 24 hours afterward due to potential disulfiram-like reaction 3, 1, 2, 5

Contraceptive Barrier Considerations

• Clindamycin cream and ovules are oil-based and may weaken latex condoms and diaphragms 3, 1, 2
• Patients should be counseled about alternative contraceptive methods during treatment 3

Follow-Up and Recurrence Management

• Follow-up visits are unnecessary if symptoms resolve 3, 1, 2
• For pregnant high-risk women, a follow-up evaluation at 1 month after completion of treatment should be considered to evaluate treatment success 3
• Recurrence is common, with 50-80% of women experiencing BV recurrence within one year of completing antibiotic treatment 7, 8
• For recurrent BV, extended metronidazole treatment (500 mg twice daily for 10-14 days) is recommended; if ineffective, metronidazole vaginal gel 0.75% for 10 days followed by twice weekly for 3-6 months is an alternative 8

Management of Sex Partners

• Routine treatment of male sex partners is NOT recommended as it has not been shown to influence a woman's response to therapy or reduce recurrence rates 3, 1, 2, 6

Common Pitfalls to Avoid

• Do not use single-dose metronidazole 2g as first-line therapy due to lower efficacy (84% vs 95%) 3, 1
• Do not use clindamycin vaginal cream during pregnancy due to increased preterm delivery risk 5
• Do not assume metronidazole gel is effective for trichomoniasis—it only works for BV 5
• Do not neglect to counsel about alcohol avoidance with nitroimidazole antibiotics 3, 1, 2
• Recognize that BV is associated with PID, endometritis, and vaginal cuff cellulitis after invasive procedures, making preoperative screening important 3, 5