Overgrowth of anaerobic bacteria in the vagina

Aetiology

• Caused by a loss of the lactobacilli ‘friendly bacteria’ in the vagina
• Examples of anaerobic bacteria associated with bacterial vaginosis are:
  • Gardnerella vaginalis (most common)
  • Mycoplasma hominis
  • Prevotella species

Risk factors

• Multiple sexual partners (although it is not sexually transmitted)
• Excessive vaginal cleaning (douching, use of cleaning products and vaginal washes)
• Recent antibiotics
• Smoking
• Copper coil

Pathophysiology

• Lactobacilli are the main component of the healthy vaginal bacterial flora
• These bacteria produce lactic acid that keeps the vaginal pH low (under 4.5)
• The acidic environment prevents other bacteria from overgrowing
• When there are reduced numbers of lactobacilli in the vagina, the pH rises
• This more alkaline environment enables anaerobic bacteria to multiply

Clinical features

Symptoms

• The standard presenting feature of bacterial vaginosis is a fishy-smelling watery grey or white vaginal discharge
• Half of women with BV are asymptomatic