Treatment of Gardnerella (Bacterial Vaginosis)
Metronidazole 500 mg orally twice daily for 7 days is the recommended first-line treatment for Gardnerella vaginalis-associated bacterial vaginosis, with proven superior efficacy compared to alternative regimens. 1
Recommended First-Line Regimens
The CDC guidelines establish three equally acceptable first-line options 1:
- Metronidazole 500 mg orally twice daily for 7 days 1
- Metronidazole gel 0.75%, one full applicator (5 g) intravaginally once daily for 5 days 1
- Clindamycin cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days 1
The oral metronidazole regimens demonstrate equal efficacy, while vaginal clindamycin cream appears less efficacious than metronidazole regimens 1. Research confirms metronidazole's effectiveness with cure rates of 87-91% at 7 days post-treatment 2, and it remains the drug of choice because it targets not only Gardnerella but also the anaerobic bacteria that characterize BV 3.
Alternative Regimens (Lower Efficacy)
When first-line options are not suitable 1:
- Metronidazole 2 g orally as a single dose (lower efficacy but improved compliance) 1
- Clindamycin 300 mg orally twice daily for 7 days 1
- Clindamycin ovules 100 g intravaginally once at bedtime for 3 days 1
The single 2 g dose of metronidazole shows comparable short-term efficacy (71% cure at final assessment) but is considered an alternative due to slightly lower overall effectiveness 2, 4.
Critical Patient Counseling
Patients must avoid alcohol consumption during metronidazole treatment and for 24 hours after completion to prevent disulfiram-like reactions 1. Clindamycin cream and ovules are oil-based and may weaken latex condoms and diaphragms 1.
Special Populations Requiring Treatment
High-Risk Pregnant Women
Pregnant women with asymptomatic BV who previously delivered a premature infant should be evaluated for treatment, as therapy may reduce the risk for prematurity 1. The established benefit in all pregnant women is relief of vaginal symptoms and potential reduction of infectious complications 1.
Pre-Surgical Patients
Screen and treat women with BV before surgical abortion or hysterectomy in addition to routine prophylaxis, as treatment substantially reduces postoperative infectious complications by 10-75% 1. Two randomized controlled trials demonstrated that metronidazole treatment substantially reduced post-abortion PID 1.
Follow-Up and Recurrence Management
Follow-up visits are unnecessary if symptoms resolve 1. Because BV recurrence is common, advise patients to return if symptoms recur 1. For recurrent disease, use another recommended treatment regimen rather than repeating the same therapy 1.
Microbiological Considerations
Metronidazole and its hydroxy metabolite effectively eradicate Gardnerella vaginalis, Bacteroides species, and Mobiluncus species from vaginal specimens 2. The hydroxy metabolite shows markedly increased activity against Gardnerella (median MIC 4 mg/L vs 32 mg/L for metronidazole alone) 2. Bacteroides organisms demonstrate high susceptibility with median MIC of 1 mg/L 2.
Partner Management
No long-term maintenance therapy or routine partner treatment is recommended for uncomplicated BV 1. However, sexual partners should be evaluated if the patient experiences recurrent infections despite appropriate treatment.