What is the recommended treatment for a sexually active adult with a history of sexually transmitted infections (STIs) suspected of having bacterial vaginosis?

Treatment of Bacterial Vaginosis in Sexually Active Adults with STI History

For a sexually active adult with a history of STIs suspected of having bacterial vaginosis, treat with oral metronidazole 500 mg twice daily for 7 days, which achieves a 95% cure rate and is the CDC's preferred first-line regimen. 1, 2

Diagnostic Confirmation Before Treatment

• Diagnose BV using either Amsel's clinical criteria (3 of 4 required: homogeneous discharge, pH >4.5, positive whiff test, clue cells >20%) or Gram stain with Nugent scoring (score ≥4) 3, 2
• Do NOT culture for Gardnerella vaginalis as it can be isolated from 50% of normal women and is not specific 4, 2
• Only treat symptomatic disease unless the patient is undergoing surgical abortion or other high-risk invasive procedures 4, 1, 2

First-Line Treatment Options

Oral Therapy (Preferred)

• Metronidazole 500 mg orally twice daily for 7 days achieves 95% cure rate and is the gold standard 4, 1, 2
• Patients MUST avoid alcohol during treatment and for 24 hours afterward to prevent disulfiram-like reactions 4, 1, 2
• Expect mild-to-moderate gastrointestinal upset and unpleasant metallic taste 4, 1

Intravaginal Therapy (Equally Effective Alternative)

• Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days is equally effective as oral therapy but with fewer systemic side effects (achieves <2% of oral serum concentrations) 1, 2
• Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days is another first-line option 4, 1, 2
• Critical warning: Clindamycin cream is oil-based and will weaken latex condoms and diaphragms for several days after use 1, 2

Alternative Regimens (Lower Efficacy)

• Metronidazole 2g orally as a single dose has only 84% cure rate (versus 95% for 7-day regimen) but may be useful when compliance is a concern 4, 1, 2
• Oral clindamycin 300 mg twice daily for 7 days is an alternative when metronidazole cannot be used 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 5

Special Considerations for This Patient Population

Pre-Procedure Screening and Treatment

Given the STI history, this patient may undergo procedures that increase infection risk:

• Screen and treat ALL women (symptomatic or asymptomatic) before surgical abortion because metronidazole treatment substantially reduces post-abortion pelvic inflammatory disease 4, 1, 2
• Consider treatment before hysterectomy, endometrial biopsy, hysterosalpingography, IUD placement, or uterine curettage as BV increases risk of endometritis, PID, and vaginal cuff cellulitis 4, 2

Partner Management

• Do NOT routinely treat male sex partners as clinical trials demonstrate this does not influence treatment response or reduce recurrence rates 4, 1, 2, 3
• Instruct patient to avoid sex until therapy is completed and symptoms resolve 4

Metronidazole Allergy or Intolerance

If the patient has true metronidazole allergy:

• Use clindamycin cream 2% intravaginally at bedtime for 7 days as the preferred alternative 1, 2
• Oral clindamycin 300 mg twice daily for 7 days achieves 93.9% cure rate 2
• Never administer metronidazole gel vaginally to patients with oral metronidazole allergy as true allergy is a contraindication to all metronidazole formulations 2

Follow-Up and Recurrence Management

• No follow-up visit is necessary if symptoms resolve 4, 1, 2, 6
• Recurrence occurs in approximately 50% of women within 1 year of treatment 7, 6
• For recurrent BV, use metronidazole 500 mg twice daily for 10-14 days; if ineffective, consider metronidazole gel 0.75% for 10 days followed by twice weekly for 3-6 months 7, 6
• No long-term maintenance regimen beyond 3-6 months is currently recommended 6, 2

Common Pitfalls to Avoid

• Do not treat asymptomatic BV unless the patient is undergoing surgical abortion or high-risk invasive procedures—this represents overtreatment and unnecessary antibiotic exposure 2
• Do not use single-dose metronidazole 2g as first-line therapy due to lower cure rate (84% vs 95%) 4, 1
• Do not treat male partners routinely as this does not improve outcomes 4, 1, 2
• Do not prescribe clindamycin cream without warning about latex condom/diaphragm weakening 1, 2