What is the treatment for bacterial vaginosis?

Treatment of Bacterial Vaginosis

The first-line treatment for bacterial vaginosis is metronidazole 500 mg orally twice daily for 7 days, which achieves a 95% cure rate and is recommended by the CDC. 1

Diagnosis Before Treatment

Bacterial vaginosis should be diagnosed using Amsel's criteria, requiring at least 3 of the following 4 findings: 1

• Homogeneous white non-inflammatory vaginal discharge
• Clue cells on microscopic examination
• Vaginal pH greater than 4.5
• Positive whiff test (fishy odor with 10% KOH)

Alternatively, Gram stain showing a Nugent score ≥4 can confirm the diagnosis. 2

Standard Treatment Regimens

First-Line Options

Metronidazole 500 mg orally twice daily for 7 days is the preferred treatment with the highest cure rate. 1

Alternative Regimens

If metronidazole is not tolerated or contraindicated, use: 1

• Clindamycin cream 2% intravaginally at bedtime for 7 days
• Metronidazole gel 0.75% intravaginally twice daily for 5 days

Additional FDA-Approved Option

Tinidazole is also FDA-approved for bacterial vaginosis with two regimens: 3

• Tinidazole 2 g orally once daily for 2 days (therapeutic cure rate 27.4%)
• Tinidazole 1 g orally once daily for 5 days (therapeutic cure rate 36.8%)

Note that tinidazole cure rates are lower than metronidazole because FDA trials required resolution of all 4 Amsel criteria plus Nugent score normalization, whereas earlier metronidazole studies used less stringent criteria. 3

Critical Patient Instructions

Patients must avoid alcohol during metronidazole or tinidazole treatment and for 24 hours after completion to prevent disulfiram-like reactions (flushing, nausea, vomiting, tachycardia). 1, 4

Who Should Be Treated

All symptomatic women require treatment regardless of pregnancy status. 1

Asymptomatic women generally should NOT be treated, except for: 1, 4

• Pregnant women with history of preterm delivery
• Women undergoing surgical abortion or hysterectomy

Treatment in Pregnancy

All symptomatic pregnant women must be treated due to associations with preterm birth, premature rupture of membranes, preterm labor, and postpartum endometritis. 1, 4

For pregnant women, use oral metronidazole (systemic therapy preferred over vaginal preparations to address potential subclinical upper tract infection). 2, 5 Treatment should occur in the second trimester (13-24 weeks). 2

High-risk pregnant women (prior preterm delivery) with asymptomatic BV should be evaluated and considered for treatment. 1, 4

Partner Treatment

Male partners should NOT be routinely treated, as multiple trials have demonstrated this does not prevent recurrence or alter clinical outcomes in women. 2, 1, 4

This is a common pitfall—treating partners wastes resources and contributes to antibiotic resistance without clinical benefit. 4

Recurrent Bacterial Vaginosis

For recurrent BV (recurrence within 1 year occurs in 50-80% of women): 6, 7

• Extended metronidazole 500 mg orally twice daily for 10-14 days
• If ineffective: Metronidazole gel 0.75% intravaginally for 10 days, then twice weekly for 3-6 months as suppressive therapy

Recurrence is often due to biofilm formation that protects bacteria from antimicrobials, failure of Lactobacillus recolonization, and possibly antimicrobial resistance. 7, 8, 9

Common Pitfalls to Avoid

• Do not treat asymptomatic low-risk women—this provides no benefit and promotes antibiotic resistance. 4
• Do not use single-dose metronidazole 2g—it has lower efficacy than the 7-day regimen. 4
• Do not treat male partners routinely—this strategy is ineffective. 2, 1, 4
• Do not forget alcohol counseling—disulfiram-like reactions can be severe. 1, 4