Bacterial Vaginosis

Introduction

Bacterial Vaginosis is 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, and Mobiluncus curtisii.
The cause of the microbial alteration is not fully understood.
The associated malodour is due to the release of amines produced by anaerobic bacteria that decarboxylate lysine to  caverdine, and arginine to putrescine.

Predisposing factors

  • Use of antiseptic/antibiotic vaginal preparations
  • vaginal douching

Clinical features

  • Malodorous and increased white vaginal discharge that is homogenous, low in
    viscosity, and uniformly coats vaginal walls
  • The fishy-smelling discharge is particularly noticeable after sexual intercourse; usually no
    pruritus or inflamed vulvae

Differential diagnoses

  • Other causes of vaginal discharge e.g. Gonorrhoea.

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)
  • Fishy odour from the biogenic amines; altered by addition of 10% KOH (Sniff test)
  • Clue cells on a wet mount
    • Clue cells are normal vaginal epithelial cells studded with bacteria, giving the cells a granular appearance

Treatment objective

  • To eliminate the organisms

Drug therapy

Recommended regimen:

  • Metronidazole 400 mg orally, every 12 hous 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 200 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 contraindications

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 such as 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