Infectious DiseasesTier 2Disease (DEADMAN)

Genito-urinary conditions - vaginosis

Description

Bacterial vaginosis is a disruption of normal vaginal flora (loss of protective lactobacilli, overgrowth of anaerobic bacteria including Gardnerella vaginalis) rather than a single-organism infection or an STI in the traditional sense - though it is more common in sexually active women

Epidemiology

The most common cause of abnormal vaginal discharge in women of reproductive age

Aetiopathogenesis

Reduced lactobacilli (normally maintaining an acidic vaginal pH that suppresses anaerobic overgrowth) allows anaerobic bacterial proliferation, raising vaginal pH and producing the characteristic thin, grey, fishy-odour discharge

Diagnosis

Clinical diagnosis supported by Amsel criteria (thin grey discharge, vaginal pH >4.5, positive whiff test with potassium hydroxide, clue cells on microscopy - 3 of 4 required) or Gram stain scoring (Nugent score) in laboratory settings

Management

Metronidazole (oral or topical/vaginal) is first-line treatment; recurrence is common and may require a longer or repeated course
Treatment in pregnancy is recommended given an association with preterm birth, though evidence for reducing this specific outcome through treatment is mixed

Associations

Preterm birth association in pregnancy, recurrence (common), increased HIV acquisition/transmission risk with untreated BV, distinction from candidiasis and trichomoniasis (the other common discharge causes)

Natural history & complications

Bacterial vaginosis reflects a flora imbalance rather than a discrete pathogen - partner treatment is not routinely recommended (unlike for STIs), which is a frequently tested point distinguishing its management from the STI-focused approach used for chlamydia, gonorrhoea, or trichomoniasis

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