Bacterial vaginosis, also known as vaginal bacteriosis, is the most common cause of vaginal infection for women of childbearing age.
Although it frequently develops after sexual intercourse with a new partner, bacterial vaginosis (BV) is not considered as a sexually transmitted infection (STI). A woman who has never had sexual intercourse can have it.
An imbalance in vaginal bacteria can lead to bacterial vaginosis.
Most women with BV have no symptoms.
If symptoms occur, they include vaginal discharge, burning, and itching.
Vaginal discharge may:
- Be watery and thin
- Be gray or white in color
- Have a strong and unpleasant smell, often described as fishy
Less commonly, there may be:
- A burning sensation during urination
- Itching around the outside of the vagina
BV is caused by an imbalance of naturally occurring bacterial flora, the usual bacteria found in a woman's vagina.
It should not be confused with candidiasis, a yeast infection, or Trichomonas vaginalis (T. vaginalis), or trichomoniasis, also known as trich. These are not caused by bacteria.
The Centers for Disease Control and Prevention (CDC) estimate that 29.2 percent of American women aged 14-49 experience BV, but 84 percent of them report no symptoms.
BV occurs when there is an imbalance of bacteria in the vagina.
Doctors say treatment is not required if a woman has BV but no symptoms. Sometimes BV can appear and disappear for no apparent reason.
We know that bacterial vaginosis is linked to an imbalance in the bacteria that are normally found in a female's vagina, but why this imbalance occurs is unclear.
All parts of the body have bacteria, but some are beneficial while others are harmful. When there are too many harmful bacteria, problems can arise.
The vagina contains mostly "good" bacteria and some harmful bacteria. BV occurs when the harmful bacteria grow in numbers.
A female's vagina should contain bacteria called lactobacilli. These bacteria produce lactic acid, making the vagina slightly acidic. This prevents other bacteria from growing there.
Lower levels of lactobacilli may cause the vagina to become less acidic. If the vagina is not as acidic as it should be, this can give other bacteria the chance to grow and thrive. However, exactly how these harmful bacteria are linked with BV is not known.
Any woman can develop BV, but some behaviors or activities can increase the risk.
- Douching, or using water or a medicated solution to clean the vagina
- Having a bath with antiseptic liquids
- Having a new sex partner
- Having multiple sex partners
- Using perfumed bubble baths, vaginal deodorants, and some scented soaps
- Washing underwear with strong detergents
BV cannot be caught from toilet seats, bedding, swimming pools, or touching objects.
Diagnosis and treatment
Any woman with an abnormal vaginal discharge should see their doctor as soon as possible. A doctor can diagnose BV and rule out other infections, such as gonorrhea or trich.
Pregnant women with BV should seek treatment, as there is a slightly higher risk of complications, such as giving birth preterm, before 37 weeks of pregnancy.
The doctor may be able to diagnose BV from a description of symptoms and a physical examination, during which they will look out for an unpleasant smell and a thin, white or gray discharge.
If the patient is sexually active and there is a chance she may have an STI, the doctor may order some diagnostic tests.
The doctor may use a swab or small plastic loop to collect sample cells from the vaginal wall. The pH balance of the vagina may also be measured, to assess acidity levels.
Antibiotic medication is effective in up to 90 percent of cases, but BV often comes back again within a few weeks.
Although BV often clears up without treatment, women with signs and symptoms of BV should seek treatment to avoid complications.
Male partners do not usually need treatment, but they can spread BV between female sex partners.
Some doctors say that all women undergoing a hysterectomy or abortion should be treated for BV before their procedure, regardless of symptoms.
Metronidazole is the most common antibiotic for BV.
Oral antibiotics are normally effective against BV.
It is available:
- In tablet form, to be taken orally twice daily for 7 days. It is seen as the most effective treatment, and the preferred treatment if the woman is breastfeeding or pregnant.
- In tablet form, to be taken orally as a one-time dose. BV is more likely to return with this treatment, compared to the 7-day tablet course.
- In gel form, applied to the vagina once daily, for 5 days.
Metronidazole reacts with alcohol. The combination can make the patient feel very ill. Individuals taking metronidazole should not consume alcohol for at least 48 hours afterward.
Clindamycin is an alternative antibiotic for treating BV. It may be used if metronidazole is not effective, or if the infection recurs.
When taking clindamycin, barrier contraception methods, such as latex condoms, diaphragms, and caps may be less effective.
Tinidazole is another antibiotic that is sometimes used to treat BV if metronidazole does not work or if BV recurs. It is taken by mouth as a single dose. Alcohol must be avoided when taking this medication.
If symptoms resolve after completing a course of antibiotics, the woman will not have to be tested for BV again.
If the following happens, further tests will be needed:
- Signs and symptoms of BV persist
- Signs and symptoms of BV go away, and then come back
- The patient is pregnant
There is anecdotal evidence that probiotics can help treat BV.
A review of studies, published in January 2014, concludes:
"Although the results of different studies are controversial, most studies have been in favor of the probiotics in the prevention or treatment of BV, and no adverse effects have been reported. Therefore, it may be helpful to recommend daily consumption of probiotic products to improve public health among women."
However, more research is needed to confirm its effectiveness.
Some complications have been linked to BV.
These include a higher risk of:
- HIV infection, as she will be more susceptible to the virus
- STIs, such as the herpes simplex virus, chlamydia, gonorrhea, and human papilloma virus (HPV)
- Post-surgical infection, for example, after an abortion or a hysterectomy
Pregnancy complications related to BV include:
- Giving birth early, known as preterm delivery
- A late miscarriage
- The amniotic sac breaking open too early
- Postpartum endometritis, an irritation or inflammation of the lining of the uterus after giving birth
- Tubal factor infertility, caused by damage to the fallopian tubes, which connect the ovaries to the uterus
- Chorioamnionitis, or inflammation of the membranes surrounding the fetus, known as the chorion and the amnion.
Chorioamnionitis significantly increases the chance of preterm labor. If the newborn survives, they have a higher risk of cerebral palsy.
In-vitro fertilization (IVF) may be less likely to succeed if a woman has BV.
BV also increases the risk of pelvic inflammatory disease (PID), an infection and inflammation of the upper female genital tract that can have severe consequences, including infertility.