Vaginosis, Bacterial

Key Features

• Defined as a polymicrobial infection of the vagina caused by an imbalance of the normal bacterial vaginal flora

• The altered flora has a paucity of hydrogen peroxide–producing lactobacilli and increased concentrations of anaerobic bacteria (Prevotella sp and Mobiluncus sp), Gardnerella vaginalis, Ureaplasma, and Mycoplasma

• Whether bacterial vaginosis is sexually transmitted is unclear, but it is associated with having multiple sex partners and increased risk of other sexually transmitted infections

• Associated with premature labor, preterm delivery, intra-amniotic infection, and postpartum endometritis in pregnant females

• Associated with PID and urinary tract infections in nonpregnant individual

Clinical Findings

• Most common symptom is a copious, malodorous, homogeneous thin gray-white vaginal discharge

• Patients may report vaginal itching or dysuria

• A fishy odor may be most noticeable after intercourse or during menses

Diagnosis

• Clinical criteria

  • Presence of thin, white discharge that smoothly coats the vaginal walls

  • Fishy (amine) odor before or after the addition of 10% KOH (whiff test)

  • pH of vaginal fluid > 4.5 determined with narrow-range pH paper

  • Presence of "clue cells" on microscopic examination; clue cells are squamous epithelial cells that have multiple bacteria adhering to them, making their borders irregular and giving them a speckled appearance

• Diagnosis requires three out of four criteria, although many female patients who fulfill these criteria have no discharge or other symptoms

Treatment

• Recommended

  • Metronidazole, 500 mg orally twice a day for 7 days or

  • Metronidazole, 0.75% gel, 5 g intravaginally once daily for 5 days or

  • Clindamycin cream, 2%, one applicator intravaginally at bedtime for 7 days

• Alternatives

  • Clindamycin, 300 mg orally twice a day for 7 days or

  • Clindamycin ovule, 100 mg intravaginally once at bedtime for 3 days or

  • Tinidazole, 2 g orally once daily for 2 days or

  • Tinidazole, 1 g orally once daily for 5 days

• Follow-up visits

  • Unnecessary if symptoms resolve

  • Recommended for high-risk patients 1 month after treatment