Overview
Bacterial vaginosis (BV) is a common condition in women. It happens when the normal balance of micro-organisms in the vagina gets disrupted.
BV can spread through sexual contact. The risk of getting BV increases when having sexual contact with new partners, and from not using condoms correctly and consistently.
Although it occurs globally, it is more common in low-resource settings and areas with limited access to healthcare.
While the exact cause of BV is not known, several bacteria are associated with it. Many of these bacteria are normally found in the healthy vagina.
BV can occur from an overgrowth of pathogens such as Gardnerella spp., Prevotella spp., Mobilincus spp., Megaspahera spp., Sneathea spp. and mixed vaginal anaerobes species with many species facilitating growth and replacing the beneficial lactobacilli that help maintain a healthy vaginal environment. There is also high concordance of BV -associated bacterial species (spp.) among sexual partners.
Symptoms
Symptoms can vary in severity. Some people with bacterial vaginosis may not notice any symptoms.
Common symptoms include:
- unusual discharge from the vagina, which may be thin and light grey or white
- a strong fishy or musty odour from the vagina
- itching or irritation around the vagina
- burning during urination.
Bacterial vaginosis is a common condition and doesn’t usually cause serious complications. However, if untreated it can lead to:
- problems in pregnancy (for example, spontaneous abortion and preterm delivery)
- higher risk of sexually transmitted infections, including HIV
- pelvic inflammatory disease.
Vaginal cleansing and douching can increase the risk of developing BV.
Diagnosis
To diagnose BV, health-care providers will discuss the patient’s medical and sexual history and conduct a genital examination to check for the presence of vaginal discharge.
Diagnosing bacterial vaginosis involves using laboratory tests along with clinical findings. One common method is the Gram stain test, which uses a light microscope to examine vaginal smears. If bacterial vaginosis is present, the test shows an abundance of gram-positive and gram-negative cocci, along with a decrease in gram-positive lactobacilli (Nugent criteria).
BV can also be diagnosed based on the presence of the following criteria (Ansel criteria):
- presence of the white homogeneous vaginal discharge: the vaginal discharge is often greyish, white, thin homogeneous and adherent to the vaginal wall (there is no obvious inflammation, hence the term vaginosis rather than vaginitis);
- by measuring the acidity level of the vaginal discharge through a pH test: a pH greater than 4.5,
- presence of an amine odour when potassium hydroxide is added to vaginal fluid (known as the Whiff test), can indicate bacterial vaginosis; and
- presence of clue cells on microscopy of a wet mount of a sample of vaginal discharge.
Clinical and laboratory assessments for bacterial vaginosis can be affected by factors such as recent sexual activity, menstrual cycle, douching, and use of antimicrobial agents.
In settings where laboratory diagnosis is not possible, syndromic approach to diagnose and treat vaginal discharge is suggested. Women who complaints with vaginal discharge are treated for BV and trichomoniasis. Metronidazole is indicated for both BV and trichomonas.
Treatment
Bacterial vaginosis can be treated and cured.
BV is best treated with the antibiotic metronidazole.
Other treatments include:
- metronidazole gel
- tinidazole
- clindamycin
- clindamycin gel.
Healthcare providers can diagnose bacterial vaginosis and test for other infections with similar symptoms, including:
- Neisseria gonorrhoeae (causes gonorrhoea)
- Chlamydia trachomatis (causes chlamydia)
- Mycoplasma genitalium (can cause genital infections)
- Trichomonas vaginalis (causes trichomoniasis).
These infections may require different treatments.
WHO response
WHO works with partners and Member States to reduce the burden of bacterial vaginosis globally. This work includes developing research and evidence to better understand the epidemiology, burden and impact of BV, particularly in low- and middle-income countries.
In 2021 WHO’s Global HIV, Hepatitis and Sexually Transmitted Infections Program published Guidelines for the management of symptomatic sexually transmitted infections to provide updated, evidence-informed clinical and practical recommendations on case management of people with STIs.