CLINICAL ACTIONS:

Bacterial Vaginosis (BV) occurs when normal hydrogen peroxide producing Lactobacillus sp. is replaced by multiple bacteria. If a woman presents with symptoms, including vaginal discharge, irritation and malodor:

• Diagnose BV if 3 of the following (Amsel) clinical criteria are present:
  • Homogeneous, thin, white discharge that smoothly coats the vaginal walls
  • Clue cells (e.g., vaginal epithelial cells studded with adherent coccobacilli) on microscopic examination
  • pH of vaginal fluid >4.5
  • Fishy odor of vaginal discharge before or after addition of 10% KOH (i.e., the whiff test)

                 OR

• Gram stain (gold standard) to determine relative concentration of
  • Lactobacillus (long Gram-positive rods)
  • Gram-negative and Gram-variable rods and cocci (i.e., G. vaginalis, Prevotella, Porphyromonas, and peptostreptococci)
  • Gram-negative rods (i.e., Mobiluncus)
• Affirm VP III (Becton Dickinson, Sparks, MD), a DNA hybridization probe test for high concentrations of G. vaginalis
• OSOM BV Blue test (Sekisui Diagnostics, Framingham, MA), which detects vaginal fluid sialidase activity, have acceptable performance characteristics compared with Gram stain
• Do NOT use Pap tests
• Do NOT culture for G. vaginalis 

Vaginal wet mount with a NaCl preparation, showing a clue cell at bottom left, and two normal epithelial cells.

SYNOPSIS:

Bacterial Vaginosis (BV) is not caused by a single bacterium, but by high concentrations of anaerobic bacteria (e.g., Prevotella sp. and Mobiluncus sp.), G. vaginalis, Ureaplasma, Mycoplasma, and numerous other anaerobes. BV is associated with multiple or new sex partners, lack of condom use and in particular lack of vaginal lactobacillus.

KEY POINTS:

Treatment is recommended for women with symptoms, including discharge, irritation and malodor and may reduce the risk for C. trachomatis, N. gonorrhoeae, T. vaginalis, HIV, and herpes simplex type 2.

Recommended CDC regimens include the following:

• Metronidazole* 500 mg orally twice a day for 7 days OR
• Metronidazole* gel 0.75%, one full applicator (5 g) intravaginally, once a day for 5 days OR
• Clindamycin+ cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days

Alternative Regimens

• Tinidazole* 2 g orally once daily for 2 days OR
• Tinidazole* 1 g orally once daily for 5 days OR
• Clindamycin+ 300 mg orally twice daily for 7 days OR
• Clindamycin+ ovules 100 mg intravaginally once at bedtime for 3 days

*Alcohol consumption should be avoided during treatment with nitroimidazoles. To reduce the possibility of a disulfiram-like reaction, abstinence from alcohol use should continue for 24 hours after completion of metronidazole and 72 hours after completion of tinidazole.

+Clindamycin ovules use an oleaginous base that might weaken latex or rubber products (e.g., condoms and vaginal contraceptive diaphragms). Use of such products within 72 hours following treatment with clindamycin ovules is not recommended.

• Evidence is insufficient to recommend routine screening for BV in asymptomatic pregnant women at high or low risk for preterm delivery for the prevention of preterm birth 
• Test all women with BV for HIV and other sexually transmitted diseases (STDs)
• Follow-up visits are unnecessary if symptoms resolve
• Routine treatment of sex partners in not recommended
• Using a different recommended treatment regimen can be considered in women who have a recurrence
  • Retreatment with the same recommended regimen is an acceptable approach for treating persistent or recurrent BV after the first occurrence
• For women with multiple recurrences after completion of a recommended regimen, 0.75% metronidazole gel twice weekly for 4–6 months has been shown to reduce recurrences, although this benefit might not persist when suppressive therapy is discontinued

Note: Secnidazole is a new oral treatment for BV | 5-nitroimidazole with a longer half-life than metronidazole | Dosage is 2-gram packet of granules once orally

Learn More – Primary Sources:

CDC 2015 STD Treatments Guidelines – Bacterial Vaginosis

NEJM Review: Bacterial Vaginosis and Desquamative Inflammatory Vaginitis

Related ObG Topics:

Screening for Sexually Transmitted Diseases – Who, When and How Often?

Diagnosing Vaginitis – Why the Office Visit Still Matters

Persistent Vaginitis: Tools and Tips in Diagnosis and Treatment

STD Screening in Pregnancy: CDC Recommendations

FDA Approves Secnidazole: Single-Dose Oral Treatment for BV