What is BV?

Bacterial vaginosis (BV) is a condition that happens when there are too much of certain bacteria in the vagina. This changes the normal balance of bacteria in the vagina.

Symptom Overview

BV occurs when the balance between “good” and “harmful” bacteria is thrown off. Often there are no symptoms at all, but sometimes BV is accompanied by unusual discharge, strong odor, painful urination, itching, or burning.

How common is bacterial vaginosis?

Bacterial vaginosis is the most common vaginal infection in women ages 15-44.

How is bacterial vaginosis spread?

Researchers do not know the cause of BV or how some women get it. We do know that the infection typically occurs in sexually active women.

BV is linked to an imbalance of “good” and “harmful” bacteria that are normally found in a woman’s vagina.

Having a new sex partner or multiple sex partners, as well as douching, can upset the balance of bacteria in the vagina. This places a woman at increased risk of getting BV.

We also do not know how sex contributes to BV.  There is no research to show that treating a sex partner affects whether or not a woman gets BV. Having BV can increase your chances of getting other STDs.

BV rarely affects women who have never had sex. You cannot get BV from toilet seats, bedding, or swimming pools.

How can I avoid getting bacterial vaginosis?

Doctors and scientists do not completely understand how BV spreads. There are no known best ways to prevent it.

The following basic prevention steps may help lower your risk of developing BV:

  • Not having sex;
  • Limiting your number of sex partners; and
  • Not touching.

I’m pregnant. How does bacterial vaginosis affect my baby?

Pregnant women can get BV. Pregnant women with BV are more likely to have babies born premature (early) or with low birth weight than pregnant women without BV. Low birth weight means having a baby that weighs less than 5.5 pounds at birth.

Treatment is especially important for pregnant women.

How do I know if I have bacterial vaginosis?

Many women with BV do not have symptoms. If you do have symptoms, you may notice:

  • A thin white or gray vaginal discharge;
  • Pain, itching, or burning in the vagina;
  • A strong fish-like odor, especially after sex;
  • Burning when urinating;
  • Itching around the outside of the vagina.

How will my doctor know if I have bacterial vaginosis?

A health care provider will examine your vagina for signs of vaginal discharge. Your provider can also perform laboratory tests on a sample of vaginal fluid to determine if BV is present.

Can bacterial vaginosis be cured?

BV will sometimes go away without treatment. But if you have symptoms of BV you should be checked and treated. It is important that you take all of the medicine prescribed to you, even if your symptoms go away.

A health care provider can treat BV with antibiotics, but BV may return even after treatment. Treatment may also reduce the risk for some STDs.

Male sex partners of women diagnosed with BV generally do not need to be treated. BV may be transferred between female sex partners.

What happens if I don’t get treated?

BV can cause some serious health risks, including:

  • Increasing your chance of getting HIV if you have sex with someone who is infected with HIV;
  • If you are HIV positive, increasing your chance of passing HIV to your sex partner;
  • Making it more likely that you will deliver your baby too early if you have BV while pregnant;
  • Increasing your chance of getting other STDs, such as chlamydia and gonorrhea. These bacteria can sometimes cause pelvic inflammatory disease (PID), which can make it difficult or impossible for you to have children.

Prevalence

Bacterial vaginosis is the most common cause of vaginal symptoms among women, but it is not clear what role sexual activity plays in the development of BV.

The prevalence in the United States is estimated to be 21.2 million (29.2%) among women ages 14–49, based on a nationally representative sample of women who participated in NHANES 2001–2004. The following are other findings from this study.

  • Most women found to have BV (84%) reported no symptoms.
  • Women who have not had vaginal, oral, or anal sex can still be affected by BV (18.8%), as can pregnant women (25%), and women who have ever been pregnant (31.7%).
  • Prevalence of BV increases based on the lifetime number of sexual partners.
  • Non-white women have higher rates (African-American 51%, Mexican Americans 32%) than white women (23%).

Can bacterial vaginosis be cured?

BV will sometimes go away without treatment. But if you have symptoms of BV you should be checked and treated.

It is important that you take all of the medicine prescribed to you, even if your symptoms go away.

A health care provider can treat BV with antibiotics, but BV may recur even after treatment. Treatment may also reduce the risk for some STDs.

Male sex partners of women diagnosed with BV generally do not need to be treated. BV may be transferred between female sex partners.

Treatment

Treatment is recommended for women with symptoms. The established benefits of therapy in nonpregnant women are to relieve vaginal symptoms and signs of infection.

Other potential benefits to treatment include a reduction in the risk for acquiring C. trachomatis, N. gonorrheaT. vaginalis, HIV, and herpes simplex type 2.

Recommended Regimens
  • Metronidazole 500 mg orally twice a day for 7 days
    OR
  • Metronidazole gel 0.75%, one full applicator (5 g) intravaginally, once a day for 5 days
    OR
  • Clindamycin cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days

Alcohol consumption should be avoided during treatment with nitroimidazoles. To reduce the possibility of a disulfiram-like reaction, abstinence from alcohol use should continue for 24 hours after completion of metronidazole.

Clindamycin cream is oil-based and might weaken latex condoms and diaphragms for 5 days after use (refer to clindamycin product labeling for additional information).

Women should be advised to refrain from sexual activity or use condoms consistently and correctly during the treatment regimen. Douching might increase the risk for relapse, and no data support the use of douching for treatment or relief of symptoms.

Alternative Regimens
  • Tinidazole 2 g orally once daily for 2 days
    OR
  • Tinidazole 1 g orally once daily for 5 days
    OR
  • Clindamycin 300 mg orally twice daily for 7 days
    OR
  • Clindamycin ovules 100 mg intravaginally once at bedtime for 3 days*

*Clindamycin ovules use an oleaginous base that might weaken latex or rubber products (e.g., condoms and vaginal contraceptive diaphragms). Use of such products within 72 hours following treatment with clindamycin ovules is not recommended.

Alcohol consumption should be avoided during treatment with nitroimidazoles. To reduce the possibility of a disulfiram-like reaction, abstinence from alcohol use should continue for 72 hours after completion of tinidazole. Alternative regimens include several tinidazole regimens or clindamycin (oral or intravaginal).

An additional regimen includes metronidazole (750-mg extended-release tablets orally once daily for 7 days); however, data on the performance of this alternative regimen are limited.

Certain studies have evaluated the clinical and microbiologic efficacy of using intravaginal lactobacillus formulations to treat BV and restore normal flora.

Overall, no studies support the addition of any available lactobacillus formulations or probiotic as an adjunctive or replacement therapy in women with BV.

Further research efforts to determine the role of these regimens in BV treatment and prevention are ongoing.

Other Management Considerations

All women with BV should be tested for HIV and other STDs.

Follow-Up

Follow-up visits are unnecessary if symptoms resolve. Because persistent or recurrent BV is common, women should be advised to return for evaluation if symptoms recur.

Detection of certain BV-associated organisms has been associated with antimicrobial resistance and might be predictive of risk for subsequent treatment failure.

Limited data are available regarding optimal management strategies for women with persistent or recurrent BV.

Using a different recommended treatment regimen can be considered in women who have a recurrence; however, retreatment with the same recommended regimen is an acceptable approach for treating persistent or recurrent BV after the first occurrence.

For women with multiple recurrences after completion of a recommended regimen, 0.75% metronidazole gel twice weekly for 4–6 months has been shown to reduce recurrences, although this benefit might not persist when suppressive therapy is discontinued.

Limited data suggest that an oral nitroimidazole (metronidazole or tinidazole 500 mg twice daily for 7 days) followed by intravaginal boric acid 600 mg daily for 21 days and then suppressive 0.75% metronidazole gel twice weekly for 4–6 months for those women in remission might be an option for women with recurrent BV.

Monthly oral metronidazole 2g administered with fluconazole 150 mg has also been evaluated as suppressive therapy; this regimen reduced the incidence of BV and promoted colonization with normal vaginal flora.

Management of Sex Partners

Data from clinical trials indicate that a woman’s response to therapy and the likelihood of relapse or recurrence are not affected by the treatment of her sex partner(s). Therefore, routine treatment of sex partners is not recommended.

Special Considerations

Allergy, Intolerance, or Adverse Reactions

Intravaginal clindamycin cream is preferred in case of allergy or intolerance to metronidazole or tinidazole.

Intravaginal metronidazole gel can be considered for women who are not allergic to metronidazole but do not tolerate oral metronidazole.

It is advised to avoid consuming alcohol during treatment with nitroimidazoles. To reduce the possibility of a disulfiram-like reaction, abstinence from alcohol use should continue for 24 hours after completion of metronidazole or 72 hours after completion of tinidazole.

Pregnancy

Treatment is recommended for all symptomatic pregnant women. Studies have been undertaken to determine the efficacy of BV treatment among this population, including two trials demonstrating that metronidazole was efficacious during pregnancy using the 250-mg regimen; however, metronidazole administered at 500 mg twice daily can be used.

One trial involving a limited number of participants revealed treatment with oral metronidazole 500 mg twice daily to be equally effective as metronidazole gel, with cure rates of 70% using Amsel criteria to define cure.

Another trial demonstrated a cure rate of 85% using Gram-stain criteria after treatment with oral clindamycin.

Multiple studies and meta-analyses have failed to demonstrate an association between metronidazole use during pregnancy and teratogenic or mutagenic effects in newborns.

Although older studies indicated a possible link between the use of vaginal clindamycin during pregnancy and adverse outcomes for the newborn, newer data demonstrate that this treatment approach is safe for pregnant women.

Because oral therapy has not been shown to be superior to topical therapy for treating symptomatic BV in effecting a cure or preventing adverse outcomes of pregnancy, symptomatic pregnant women can be treated with either of the oral or vaginal regimens recommended for nonpregnant women.

Although adverse pregnancy outcomes, including premature rupture of membranes, preterm labor, preterm birth, intra-amniotic infection, and postpartum endometritis have been associated with symptomatic BV in some observational studies, treatment of BV in pregnant women can reduce the signs and symptoms of vaginal infection.

A meta-analysis has concluded that no antibiotic regimen prevented preterm birth (early or late) in women with BV (symptomatic or asymptomatic).

However, in one study, oral BV therapy reduced the risk for late miscarriage, and in two additional studies, such therapy decreased adverse outcomes in the neonate.

Treatment of asymptomatic BV among pregnant women who are at high risk for preterm delivery (i.e., those with a previous preterm birth) has been evaluated by several studies, which have yielded mixed results.

Seven trials have evaluated treatment of pregnant women with asymptomatic BV at high risk for preterm delivery: one showed harm, two showed no benefit, and four demonstrated benefit.

Similarly, data are inconsistent regarding whether treatment of asymptomatic BV among pregnant women who are at low risk for preterm delivery reduces adverse outcomes of pregnancy.

One trial demonstrated a 40% reduction in spontaneous preterm birth among women using oral clindamycin during weeks 13–22 of gestation.

Several additional trials have shown that intravaginal clindamycin given at an average gestation of >20 weeks did not reduce the likelihood of preterm birth.

Therefore, the evidence is insufficient to recommend routine screening for BV in asymptomatic pregnant women at high or low risk for preterm delivery for the prevention of preterm birth.

Although metronidazole crosses the placenta, no evidence of teratogenicity or mutagenic effects in infants has been found in multiple cross-sectional and cohort studies of pregnant women. Data suggest that metronidazole therapy poses a low risk in pregnancy.

Metronidazole is secreted in breast milk. With maternal oral therapy, breastfed infants receive metronidazole in doses that are less than those used to treat infections in infants, although the active metabolite adds to the total infant exposure.

Plasma levels of the drug and metabolite are measurable but remain less than maternal plasma levels (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACTExternal).

Although several reported case series found no evidence of Metronidazole-associated adverse effects in breastfed infants, some clinicians advise deferring breastfeeding for 12–24 hours following maternal treatment with a single 2-g dose of metronidazole.

Lower doses produce a lower concentration in breast milk and are considered compatible with breastfeeding.

Data from studies of human subjects are limited regarding the use of tinidazole in pregnancy; however, animal data suggest that such therapy poses a moderate risk. Thus tinidazole should be avoided during pregnancy.

Considerations

BV is considered a sexually associated infection, not specifically an STI. This is because it can be spread through sexual contact, but women can also get this infection unrelated to sexual activity. It is simply an imbalance in the bacteria in the vagina.

Type of test

A health care provider will examine the vagina for signs of BV and take a sample of vaginal fluid to be examined under a microscope or sent to a lab for testing.

Schedule the test when you are not on your period. Do not have sex, douche or use a tampon within 24 hours of your exam.

Test Timing

It depends on the lab used by your health care provider, but usually a couple of days to a week.

Protecting Yourself

As with all STIs, the most effective protection is to abstain from sexual activity or be monogamous with one long-term partner who has tested negative for BV.

Using latex condoms or dental dams can help reduce the risk of contracting or spreading the infection. Also avoid douching, as this can remove good bacteria and make BV worse.