What is the treatment for bacterial vaginosis?

Symptoms and Treatment of Bacterial Vaginosis

Bacterial vaginosis (BV) is characterized by a homogeneous white discharge, fishy odor, and should be treated with metronidazole 500 mg orally twice daily for 7 days as first-line therapy for symptomatic women. 1, 2

Diagnostic Criteria

BV is diagnosed when at least 3 of the following 4 Amsel criteria are present:

• Homogeneous, white, non-inflammatory discharge that smoothly coats the vaginal walls 1
• Presence of clue cells on microscopic examination 1
• Vaginal fluid pH greater than 4.5 1
• Fishy odor of vaginal discharge before or after addition of 10% KOH (whiff test) 1

Alternatively, Gram stain can be used to determine the relative concentration of bacterial morphotypes characteristic of BV 1, 2

Pathophysiology

BV results from replacement of normal H₂O₂-producing Lactobacillus species in the vagina with high concentrations of:

• Anaerobic bacteria (e.g., Prevotella sp. and Mobiluncus sp.)
• Gardnerella vaginalis
• Mycoplasma hominis 1, 3

Importantly, up to 50% of women with BV are asymptomatic despite meeting clinical criteria 1, 3

Treatment Recommendations

First-Line Treatment for Non-Pregnant Women

• Metronidazole 500 mg orally twice daily for 7 days 1, 2
• Clindamycin cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days 1
• Metronidazole gel 0.75%, one full applicator (5 g) intravaginally twice daily for 5 days 1, 4

Alternative Regimens

• Metronidazole 2 g orally in a single dose (note: lower efficacy than 7-day regimen) 1, 5
• Clindamycin 300 mg orally twice daily for 7 days 1
• Tinidazole 2 g once daily for 2 days or 1 g once daily for 5 days 6

Special Considerations

Pregnancy

• BV during pregnancy is associated with adverse pregnancy outcomes including preterm delivery 1
• Treatment should be considered for pregnant women with BV who have a history of preterm delivery 1

Before Procedures

• Women with BV should be treated before surgical abortion procedures to reduce the risk of post-abortion PID 1
• Consider treatment before other invasive gynecological procedures such as hysterectomy 2

Recurrent BV

• 50-80% of women experience recurrence within 1 year of treatment 7, 5
• Extended course of metronidazole (500 mg twice daily for 10-14 days) is recommended for recurrent BV 5
• Maintenance therapy with metronidazole vaginal gel 0.75% twice weekly for 3-6 months may be considered for persistent cases 5

Important Clinical Considerations

• Patients using metronidazole should avoid alcohol during treatment and for 24 hours afterward due to potential disulfiram-like reaction 1
• Clindamycin cream is oil-based and might weaken latex condoms and diaphragms 1
• Treatment of male sexual partners has not been shown to prevent recurrence of BV 1, 2

Common Pitfalls to Avoid

• Treating asymptomatic women unnecessarily (unless before invasive procedures or in high-risk pregnant women) 2
• Using inadequate diagnostic criteria (e.g., relying on discharge alone without microscopy or pH testing) 1, 2
• Failing to complete the full course of antibiotics, which may lead to recurrence 5
• Not warning patients about potential side effects of metronidazole (metallic taste, nausea, disulfiram-like reaction with alcohol) 1