What is the recommended antibiotic and dose for bacterial vaginosis (BV) caused by Enterococcus faecalis?

Treatment of Bacterial Vaginosis Caused by Enterococcus faecalis

Critical Clarification Required

This clinical scenario requires immediate reassessment, as Enterococcus faecalis does not cause bacterial vaginosis (BV) and represents a fundamentally different infection requiring distinct treatment.

Understanding the Distinction

Bacterial vaginosis is caused by anaerobic bacteria (Gardnerella vaginalis, Prevotella, Mobiluncus) and is treated with metronidazole or clindamycin, while E. faecalis causes aerobic vaginitis (AV), which requires completely different antibiotic therapy. 1

Key Diagnostic Differences:

• BV characteristics: pH 4.5-5.0, clue cells present, fishy odor with KOH, polymicrobial anaerobic flora 1
• AV with E. faecalis: pH >5.0, parabasal cells, inflammatory cells, absence of clue cells, aerobic pathogen dominance 2

Treatment for Aerobic Vaginitis Caused by E. faecalis

For confirmed E. faecalis vaginal infection (aerobic vaginitis), use amoxicillin 500 mg orally every 8 hours for 7 days as first-line therapy. 3

Primary Treatment Options:

• Amoxicillin 500 mg orally every 8 hours for 7 days achieves 88.1% clinical and 86% microbiological eradication rates 3
• Ampicillin 500 mg orally every 8 hours for 7 days is an equivalent alternative 3

Alternative Regimens:

• Nitrofurantoin 100 mg orally every 6 hours for 7 days for penicillin-allergic patients, with <6% resistance rates against E. faecalis 3
• Amoxicillin-clavulanate for beta-lactamase producing strains 3

Critical Management Points:

• Always obtain susceptibility testing before initiating therapy, even for "pansensitive" strains, as resistance patterns vary significantly 3
• Avoid fluoroquinolones due to 46-47% resistance rates in E. faecalis 3
• Differentiate colonization from true infection before prescribing antibiotics, as asymptomatic bacteriuria does not require treatment 3

If This Is Actually Bacterial Vaginosis (Not E. faecalis)

For standard BV, use metronidazole 500 mg orally twice daily for 7 days as the most efficacious regimen. 1

BV Treatment Regimens:

Recommended (equally efficacious):

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

Alternative (lower efficacy):

• Metronidazole 2g orally single dose 1
• Clindamycin 300 mg orally twice daily for 7 days 1

Important Counseling Points for BV Treatment:

• Avoid alcohol during metronidazole therapy and for 24 hours after completion 1
• Clindamycin cream and ovules are oil-based and weaken latex condoms and diaphragms 1
• Partner treatment is not recommended as it does not affect cure or recurrence rates 1
• Recurrence rates approach 80% at 9 months, and patients should return if symptoms recur 4

Common Clinical Pitfall

The most critical error is treating E. faecalis vaginal infection with metronidazole (the BV drug), which has no activity against this aerobic organism and will result in treatment failure. 3, 2, 5 Metronidazole targets anaerobes, while E. faecalis is an aerobic gram-positive coccus requiring beta-lactam or nitrofurantoin therapy 3, 5.

Pregnancy Considerations

For pregnant women with E. faecalis infection, amoxicillin 500 mg orally every 8 hours for 7 days remains safe and appropriate. 3 For actual BV in pregnancy, metronidazole 250 mg orally three times daily is preferred in the second and third trimesters 1.