What oral antibiotic treatment is appropriate for a vaginal swab positive for Enterococcus faecalis, Lactobacillus species, and Prevotella bivia?

Treatment for Vaginal Swab Positive for Enterococcus faecalis, Lactobacillus spp, & Prevotella bivia

Metronidazole 500 mg orally twice daily for 7 days is the recommended treatment for a vaginal swab showing Prevotella bivia, as this organism is commonly associated with bacterial vaginosis (BV). 1 The presence of Lactobacillus species is actually normal vaginal flora, while Enterococcus faecalis and Prevotella bivia suggest dysbiosis consistent with BV.

Diagnostic Considerations

Before initiating treatment, confirm that the patient meets clinical criteria for BV, which requires three of the following:

• Homogeneous, white, non-inflammatory discharge adhering to vaginal walls
• Presence of clue cells on microscopic examination
• Vaginal fluid pH greater than 4.5
• Fishy odor of vaginal discharge before or after addition of 10% KOH (whiff test) 2

Prevotella bivia is a key anaerobic organism associated with BV and treatment failure 3, making appropriate antibiotic therapy essential.

Treatment Options

First-line Treatment:

• Metronidazole 500 mg orally twice daily for 7 days 1

Alternative Regimens:

• Metronidazole 2 g orally in a single dose (lower cure rate of 84% vs 95% for 7-day regimen) 2
• Clindamycin 300 mg orally twice daily for 7 days 1
• 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

Important Precautions

• Patients must avoid alcohol during metronidazole treatment and for 24 hours afterward to prevent disulfiram-like reactions 1
• Clindamycin cream is oil-based and may weaken latex condoms and diaphragms 1
• Follow-up visits are unnecessary if symptoms resolve 2

Management of Recurrence

Recurrence is common, with 50-80% of women experiencing recurrence within a year of treatment 4. This may be due to:

• Persistence of biofilms protecting BV-causing bacteria 5
• Higher abundance of Prevotella before treatment and persistence of Gardnerella after treatment 3
• Failure of beneficial Lactobacillus species to recolonize the vagina 4

For recurrent BV, use an extended course of metronidazole (500 mg twice daily for 10-14 days) or metronidazole vaginal gel 0.75% for 10 days, followed by twice weekly for 3-6 months 5.

Partner Treatment

Routine treatment of sex partners is not recommended by the CDC, as clinical trials indicate that partner treatment does not affect a woman's response to therapy or likelihood of relapse/recurrence 1. However, some studies suggest that women with untreated regular sexual partners may be more likely to experience recurrence than those with no partner or those whose partner received treatment 3.

Special Considerations

• If the patient is pregnant, metronidazole 250 mg orally three times daily for 7 days is recommended 1
• Before surgical procedures, treating BV may reduce post-operative infectious complications 1
• If the patient has an allergy or intolerance to metronidazole, clindamycin is the preferred alternative 2