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
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 are the use of antiseptic/antibiotic vaginal preparations or vaginal douching.
Malodorous and increased white vaginal discharge that is homogenous, low in viscosity, and uniformly coats the vaginal walls, the fishy-smelling discharge is particularly noticeable after sexual intercourse; usually no pruritus or inflamed vulvae.
Other causes of vaginal discharge: see Gonorrhoea
Premature rupture of membranes,
Preterm delivery and low birth weight,
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.
To eliminate the organisms
- Metronidazole 400 mg orally, every 12 hours for 7 days. Alternative regimen:
- Metronidazole 2g orally, as a single dose.
- Metronisazole 0.75% gel 5 g intravaginally, twice daily for 7 days.
Notable adverse drug reactions, caution
Metronidazole: see Trichnomoniasis
Advise to return if symptoms persist as re-treatment may be needed
Recommended regimen for pregnant women
Metronidazole 200 orally, every 8 hours for 7 days, after the first trimester.
2 g orally, as a single dose
If treatment is imperative in the first trimester pregnancy
Give metronidazole 2 g orally as a single dose
Notable adverse reaction, caution and contraindication
Causes a disuifiram-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.
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 preterm delivery to detect asymptomatic infections.
Retreat pregnant women with recurrence of symptoms counselling, compliance, and condom use and contact treatment.