Bacterial Vaginosis

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Introduction

  • A clinical syndrome resulting from replacement of the normal hydrogen peroxide-producing Lactobacillus sp. in the vagina by high concentrations of anaerobic bacteria, such as
    • Gardnerella vaginalis Mycoplasma hominis Mobiluncus curtisii
  • Predisposing factors are the use of antiseptic/antibiotic vaginal preparations or vaginal douching

Clinical features

  • Malodorous and increased white vaginal discharge: homogenous, low in viscosity, and uniformly coats vaginal walls (fishy-smelling discharge particularly noticeable after sexual intercourse)
  • No pruritus or inflamed vulvae

Differential diagnoses

Complications

  • Acute salpingitis
  • Premature rupture of membranes
  • Preterm delivery and low birth weight

Investigations

  • Homogeneous milky discharge with pH > 4.5 (pH > 6.0 highly suggestive)
  • Wet mount of the discharge – clue cells (normal vaginal epithelial cells studded with bacteria, giving the cells a granular appearance)
  • Whiff test - addition of several drops of 10% KOH to a sample of vaginal discharge (Fishy odour is indicative of a positive test)

Treatment goals

  • Eliminate the organisms

Drug treatment

Recommended regimen:

  • Metronidazole 400 mg orally, every 12 hours for 7 days

Alternative regimen:

  • Metronidazole 2 g orally, as a single dose

Or:

  • Metronidazole 0.75% gel 5 g intravaginally, twice for 7 days

Recommended regimen for pregnant women

  • Metronidazole 200mg orally, every 8 hours for 7 days, after the first trimester
  • Or: 2g orally, as a single dose

If treatment is imperative in the first trimester of pregnancy

  • Give metronidazole 2 g orally as a single dose

Notable adverse reactions, caution and contraindicationsMetronidazole: see Trichomoniasis

Advise to return if symptoms persist as re-treatment may be needed

Metronidazole

  • Causes a disulfiram-like reaction with alcohol
  • Avoid high doses in pregnancy and breast feeding
  • May cause nausea, vomiting, unpleasant taste, furred tongue, and gastro-intestinal disturbances
  • Generally not recommended for use in the first trimester of pregnancy

Prevention

  • Reduce or eliminate predisposing factors (antiseptic/antibiotic vaginal preparations or vaginal douching)
  • Treat symptomatic pregnant women
  • Screen pregnant women with a history of previous pre-term delivery to detect asymptomatic infections
  • Retreat pregnant women with recurrence of symptoms
  • Counselling, Compliance, Condom use and Contact treatment