What is the treatment for bacterial vaginosis?

Treatment of Bacterial Vaginosis

Treat symptomatic bacterial vaginosis with oral metronidazole 500 mg twice daily for 7 days, which achieves a 95% cure rate and is the preferred first-line therapy. 1

First-Line Treatment Options

Oral metronidazole 500 mg twice daily for 7 days is the gold standard treatment, offering the highest efficacy among all regimens and should be your default choice for non-pregnant women with symptomatic BV. 1

Alternative first-line options with comparable efficacy include:

• Metronidazole gel 0.75% intravaginally once daily for 5 days provides equal effectiveness to oral therapy but with fewer systemic side effects, making it ideal for patients who cannot tolerate oral medications or prefer local treatment. 1

• Clindamycin cream 2% intravaginally at bedtime for 7 days is another equally effective first-line option, particularly useful for patients with metronidazole allergy or intolerance. 1

When to Treat

Only symptomatic women require treatment, as the principal goal is relief of vaginal symptoms and signs. 2 However, there are important exceptions:

• Before surgical abortion procedures, treat all women with BV (symptomatic or asymptomatic) because metronidazole treatment substantially reduces post-abortion pelvic inflammatory disease. 2, 1

• Consider treatment before hysterectomy due to increased risk of vaginal cuff cellulitis and other postoperative infectious complications. 1

Alternative Regimens (Lower Efficacy)

Avoid single-dose metronidazole 2g in most cases as it has significantly lower efficacy (84% vs 95% cure rate) compared to the 7-day regimen, though it may be acceptable when compliance is a major concern. 1

• Oral clindamycin 300 mg twice daily for 7 days serves as an alternative when metronidazole cannot be used. 2, 1

• Tinidazole 2g once daily for 2 days or 1g once daily for 5 days demonstrated therapeutic cure rates of 22-32% (compared to 5% placebo) in controlled trials, though experience is more limited than with metronidazole. 3

Critical Patient Counseling Points

Patients taking metronidazole must avoid all alcohol during treatment and for 24 hours afterward to prevent a disulfiram-like reaction with severe nausea, vomiting, and flushing. 2, 1, 4

Clindamycin cream and ovules are oil-based and will weaken latex condoms and diaphragms for at least 5 days after use, requiring alternative contraception during this period. 1, 4

Special Populations

Pregnancy

All symptomatic pregnant women should be tested and treated for BV. 1

• First trimester: Use clindamycin vaginal cream as metronidazole is relatively contraindicated during this period. 1

• Second and third trimesters: Use metronidazole 250 mg orally three times daily for 7 days (note the different dosing from non-pregnant women). 1, 4

• High-risk pregnant women (history of preterm delivery) should be treated even if asymptomatic, as treatment may reduce prematurity risk. 1

HIV-Positive Patients

Treat HIV-positive patients with BV using the same regimens as HIV-negative patients—no modification is necessary. 1

Breastfeeding Women

Standard CDC guidelines apply to breastfeeding women, as metronidazole is compatible with breastfeeding despite small amounts being excreted in breast milk. 1

Perimenopausal Women

Treat perimenopausal women with standard regimens—the approach remains consistent regardless of menopausal status, though hormonal fluctuations in perimenopause may disrupt the vaginal microbiome and increase BV susceptibility. 1

Management of Sex Partners

Do not routinely treat male sex partners, as clinical trials consistently demonstrate no influence on treatment response or recurrence rates in women. 2, 1, 4 This is a common pitfall—many providers feel compelled to treat partners, but the evidence clearly shows no benefit.

Allergy Considerations

If a patient has metronidazole allergy, use clindamycin cream or oral clindamycin instead. 1

Never administer metronidazole vaginally to patients allergic to oral metronidazole—the allergy applies to both routes. 1

Follow-Up

Follow-up visits are unnecessary if symptoms resolve. 1, 4 Instruct patients to return only if symptoms recur, at which point they require additional therapy.

Understanding the Diagnosis

BV results from replacement of normal hydrogen peroxide-producing Lactobacillus species with high concentrations of anaerobic bacteria (Bacteroides, Mobiluncus), Gardnerella vaginalis, and Mycoplasma hominis. 2

Diagnose BV clinically when 3 of 4 Amsel criteria are present: 2

• Homogeneous white noninflammatory discharge adhering to vaginal walls
• Clue cells on microscopic examination
• Vaginal pH >4.5
• Fishy odor before or after adding 10% KOH (whiff test)

Do not culture Gardnerella vaginalis for diagnosis—it lacks specificity as it can be isolated from half of normal women. 2

Common Pitfalls to Avoid

• Recurrence is extremely common (50-80% within one year), likely because beneficial Lactobacillus species fail to recolonize after antibiotic treatment. 5 Set realistic expectations with patients.

• Biofilm formation may protect BV-causing bacteria from antimicrobial therapy, contributing to treatment failure and recurrence. 6

• For recurrent BV, extend treatment to metronidazole 500 mg twice daily for 10-14 days, or consider metronidazole gel 0.75% for 10 days followed by twice weekly for 3-6 months. 6