Bacterial Vaginosis: Causes, Symptoms and Treatment

The normal female vagina is colonised by bacteria, predominantly lactobacilli which maintain an acidic pH, typically less than 4.5. An alteration in the normal flora can occur with increased growth of other bacterial species. This leads to bacterial vaginosis (BV) wherein the individual experiences foul smelling, off-white vaginal discharge.

Bacterial Vaginosis is the most common cause of vaginitis (inflammation of the vagina) in women in the reproductive age group. BV is not classified as a sexually transmitted Infection (STI), as there is no single organism or male component of the disease identified so far. However, there is an association with sexual activity. In addition, women who have never been sexually active have not been known to have BV.

Causes of BV

Although bacteria are implicated in causing the disease, there is no single organism which has been identified as leading to BV. One bacterial species, Gardnerella vaginalis is found to have a significant role in causing BV by forming a biofilm (a thin layer containing bacteria which coats other structures and protects the bacteria from being attacked by external elements) around the vagina, allowing other bacterial species to survive and cause vaginitis.

Risk Factors of BV

• Unprotected sexual intercourse
• Women who have sex with women: Due to alteration of the vaginal flora during new sexual encounters.
• Douching: this changes the local vaginal pH
• Presence of other STIs
• Cigarette Smoking

Symptoms of BV

Between 50 to 75% of women with BV are asymptomatic.

• Vaginal discharge which is gray-white
• Foul smell, which is characteristically a ‘fishy odor’
• Burning and itching in the vaginal region

Complications of BV

• Increased risk of other STIs such as chlamydia and gonorrhea
• Pelvic Inflammatory disease
• Increased risk for infection following child birth
• Preterm birth in pregnant women

Diagnosis of BV

Bacterial Vaginosis is diagnosed following a physical exam, including a pelvic examination and a few laboratory tests.

• Pelvic Examination: This includes visualising the vaginal wall to look for the characteristic discharge. A swab of the discharge is also taken for investigation
• Laboratory tests:
  • Test of pH: an increase in the pH to >4.5
  • KOH whiff-amine test: this involves adding 10% KOH to the discharge. The test is positive when the reaction produces a fishy odor
  • Saline wet mount: The discharge is mixed with saline and viewed under a microscope. The presence of vaginal surface cells surrounded by bacteria, called ‘clue cells’, is suggestive of BV.

Treatment of BV

Bacterial Vaginosis is treated using antibiotics. The two most common drugs used are metronidazole and clindamycin. These are available as pills, gels or creams to be used locally in the vagina. The mode of treatment depends on the individual.

Male partners do not require treatment. Female partners should be notified of the infection in order to be prepared for treatment, should they show symptoms.

References

1. Sobel JD. Bacterial vaginosis: Clinical manifestations and diagnosis.
2. Sobel JD. Bacterial Vaginosis: Treatment. Accessed March 30, 2019
3. CDC fact sheet: Bacterial vaginosis fact sheet. Centers for Disease Control and Prevention.