Treatment for Low Bacterial Vaginosis and High Megasphaera on Vaginal Swab
For low bacterial vaginosis with high Megasphaera on vaginal swab, metronidazole 500 mg orally twice daily for 7 days is the recommended first-line treatment. 1
Diagnostic Considerations
When evaluating a vaginal swab showing low BV with high Megasphaera, it's important to understand:
- Megasphaera is one of the bacterial morphotypes associated with bacterial vaginosis
- Even with "low BV" findings, the presence of high Megasphaera indicates an imbalance in vaginal flora that requires treatment
- Diagnosis of BV typically requires 3 of 4 Amsel criteria:
- Homogeneous, white discharge that adheres to vaginal walls
- Presence of clue cells on microscopic examination
- pH of vaginal fluid >4.5
- Fishy odor before or after addition of 10% KOH (whiff test) 1
Treatment Options
First-line Treatment:
- Metronidazole 500 mg orally twice daily for 7 days (95% cure rate) 1
Alternative Options:
- Metronidazole gel 0.75% intravaginally once daily for 5 days (95% cure rate)
- Clindamycin cream 2% intravaginally at bedtime for 7 days
- Metronidazole 2g orally in a single dose (84% cure rate, but less effective than 7-day regimen) 1, 2
Important Patient Advice
- Patients must avoid alcohol during treatment with metronidazole and for 24 hours afterward due to potential disulfiram-like reaction 2, 1
- Clindamycin cream is oil-based and may weaken latex condoms and diaphragms 2
- Follow-up visits are generally not needed unless symptoms persist or recur within 2 months 1
Managing Recurrence
Recurrence is common in BV, affecting more than 50% of patients within 1 year of treatment 3. Research has shown that women with higher concentrations of Megasphaera are at increased risk for recurrent BV 4.
If BV recurs:
- Extended course of metronidazole (500 mg twice daily for 10-14 days)
- If ineffective, metronidazole vaginal gel 0.75% for 10 days, followed by twice weekly for 3-6 months 3
Special Considerations
Pregnancy: Treatment recommendations differ by trimester:
- First trimester: clindamycin cream
- Second and third trimesters: metronidazole oral or gel, or clindamycin cream 1
Before invasive procedures: Treatment of BV (symptomatic or asymptomatic) should be considered before surgical abortion procedures to reduce risk of post-procedure infection 2
Preventive Measures
- Consistent condom use may help prevent recurrence 1
- Some evidence suggests probiotics containing Lactobacillus strains may help restore normal vaginal flora 5
- Smoking cessation may offer some protection against bacterial vaginosis 1
High Megasphaera specifically has been identified as a risk factor for BV recurrence, so close monitoring and consideration of extended treatment courses may be warranted in these cases 4.