4.1 Bacterial Vaginosis Flashcards
What is bacterial vaginosis?
- Bacterial vaginosis (BV) is overgrowth of anaerobic bacteria in the vagina
- Not a sexually transmitted infection.
- Loss of the lactobacilli “friendly bacteria” in the vagina.
- Increases the risk of STIs
Lactobacilli are the main component of the healthy vaginal bacterial flora. These bacteria produce lactic acid that keeps the vaginal pH low (under 4.5). The acidic environment prevents other bacteria from overgrowing. When there are reduced numbers of lactobacilli in the vagina, the pH rises. This more alkaline environment enables anaerobic bacteria to multiply.
What bacteria are associated with bacterial vaginosis?
- Gardnerella vaginalis (most common)
- Mycoplasma hominis
- Prevotella species
It is worth remembering that bacterial vaginosis can occur alongside other infections, including candidiasis, chlamydia and gonorrhoea.
Risk factors for BV?
- Multiple sexual partners (although it is not sexually transmitted)
- Excessive vaginal cleaning (douching, use of cleaning products and vaginal washes)
- Recent antibiotics
- Smoking
- Copper coil
Bacterial vaginosis occurs less frequently in women taking the combined pill or using condoms effectively.
TOM TIP for when you are taking a history from someone with BV?
TOM TIP:
- typical Sx of BV make Dx easy based on the fishy-smelling discharge.
- assess for causes and give advice
- ask about the use of soaps to clean the vagina and vaginal douching and provide information about how these can increase the risk.
Presentation of BV?
- Fishy-smelling watery grey or white vaginal discharge
- Half of women with BV are asymptomatic.
Not: Itching, irritation and pain as these suggest an alternative cause or co-occurring infection.
- a speculum examination can be performed to confirm the typical discharge
- complete a high vaginal swab and exclude other causes of symptoms.
Examination is not always required where the symptoms are typical, and the women is low risk of sexually transmitted infections.
Investigation in BV?
Vaginal pH can be tested using a swab and pH paper. The normal vaginal pH is 3.5 – 4.5. BV occurs with a pH above 4.5.
A standard charcoal vaginal swab can be taken for microscopy. This can be a high vaginal swab taken during a speculum examination or a self-taken low vaginal swab.
Bacterial vaginosis gives “clue cells” on microscopy. Clue cells are epithelial cells from the cervix that have bacteria stuck inside them, usually Gardnerella vaginalis.
TOM TIP: Remember that clue cells on microscopy mean bacterial vaginosis. This is a common association tested in MCQ exams.
Management of BV?
Asymptomatic BV does not usually require treatment. Additionally, it may resolve without treatment.
Metronidazole (specifically targets anaerobic bacteria). PO, or vaginal gel.
Clindamycin is an alternative but less optimal antibiotic choice.
Always assess the risk of additional pelvic infections, with swabs for chlamydia and gonorrhoea where appropriate.
Provide advice and information about measures that can reduce the risk of further episodes of bacterial vaginosis, such as avoiding vaginal irrigation or cleaning with soaps that may disrupt the natural flora.
TOM TIP when prescribing metronidazole?
TOM TIP: Whenever prescribing metronidazole advise patients to avoid alcohol for the duration of treatment. This is a crucial association you should remember, and something examiners will look out for when you are explaining the treatment to a patient. Alcohol and metronidazole can cause a “disulfiram-like reaction”, with nausea and vomiting, flushing and sometimes severe symptoms of shock and angioedema.
Complications of bacterial vaginosis?
Bacterial vaginosis can increase the risk of catching sexually transmitted infections, including chlamydia, gonorrhoea and HIV.
It is also associated with several complications in pregnant women:
- Miscarriage
- Preterm delivery
- Premature rupture of membranes
- Chorioamnionitis
- Low birth weight
- Postpartum endometritis
