Bacterial vaginosis

Most common cause of abnormal vaginal discharge in people of childbearing age.
change from a Lactobacillus dominant state to one with high diversity and quantities of anaerobic bacteria including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp, Prevotella spp, and other BV-associated bacteria.
Studies have identified a polymicrobial biofilm adherent to vaginal epithelial cells of people with bacterial vaginosis.
BV-associated bacteria are present in the urethra and penile skin in partners of people with bacterial vaginosis and women who have sex with women show very high concordance for bacterial vaginosis within partnerships
strong association between acquisition of BV
- young age of first sex
- increased numbers of sex partners
- exposure to new sex partners
- lack of condom use for penile-vaginal sex.

Post-treatment recurrence of bacterial vaginosis is associated with exposure to an ongoing sex partner and lack of condom use for penile-vaginal sex.
Clinical presentation
- Malodorous vaginal discharge
- Thin white or greyish homogenous vaginal discharge
- Commonly asymptomatic (up to 50%)
Complications
- Increased risk of:
  - spontaneous abortion
  - premature labour
  - chorioamnionitis
  - postpartum endometritis
  - pelvic inflammatory disease (including after surgical termination of pregnancy, intra-uterine device (IUD) insertion or other gynaecological instrumentation)
  - acquisition of chlamydia, gonorrhoea, herpes simplex type 2
  - acquisition and transmission of human immunodeficiency virus (HIV) infection.

Diagnosis
- if 3 or 4 of the following criteria are present, presumptive treatment can be offered.
  - Thin white/grey homogenous discharge on speculum examination
  - Elevated vaginal pH (pH > 4.5)
  - Whiff test: malodour with addition of potassium hydroxide to vaginal secretions, or if not available, genital malodour on examination
  - Clue cells on microscopy of Gram stain of high vaginal swab.
Specimen collection:
- Clinician collection ensures visualisation of secretions and measurement of vaginal pH; microscopy can be performed on self-collected or clinician collected swabs smeared on a slide.

Special considerations
- Isolation of Gardnerella vaginalis (by NAAT) cannot be used to diagnose bacterial vaginosis as this organism can also be isolated in people with an optimal vaginal microbiota and no bacterial vaginosis.

Treatment advice
- Stat. dose and short-duration regimens are associated with higher rates of recurrence.
- Patients should refrain from vaginal penetrative sexual practices or use condoms consistently during treatment.
- 50% of people experience post-treatment recurrence within 3-12 months.
- Douching and intravaginal cleaning practices should be avoided.
- Copper IUDs
  - have been associated with increased risk of bacterial vaginosis acquisition and recurrence
  - If a patient using an IUD develops bacterial vaginosis, treat as recommended
  - if the patient experiences recurrent bacterial vaginosis with a copper IUD consider switching to an alternative method.
There is currently insufficient evidence to recommend the use of intravaginal lactic acid or vaginal probiotics.
Treatment is not currently recommended in partners but trials are ongoing.

Breastfeeding
- Consider intravaginal treatment. Metronidazole may affect taste of breast milk; avoid high doses in breastfeeding.
Pregnancy
- Standard treatment is recommended if symptomatic.
- There is no clinical benefit of treatment for asymptomatic patients in low-risk pregnancies.
Recurrent infection
- Intravaginal metronidazole 0.75% gel 5 g twice per week for 4 months reduces recurrence during treatment, although this benefit does not persist when discontinued.
- Intravaginal boric acid regimens (via compounding pharmacy) have also been used but have not shown sustained benefit on discontinuation.