Bacterial vaginosis

, medical expert
Last reviewed: 17.10.2021

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Bacterial vaginosis is a disease that occurs as a result of a complex violation of the vaginal microflora, in which the number of lactobacilli decreases and anaerobic infectious agents predominate. Characteristic of the following symptoms: gray, lean, unpleasant smelling vaginal discharge and itching. The diagnosis is made on the basis of clinical data and a study of the vaginal secretion. Treatment is performed using oral metronidazole or its combination with local clindamycin.

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Bacterial vaginosis is the most common vaginal infection in women of reproductive age and ranges from 5% to 70% in different periods of life.

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Causes of the bacterial vaginosis

Bacterial vaginosis is a nonspecific infection of the vagina, the cause of which is unknown. The disease causes anaerobic infectious agents such as Prevotella spp., Peptostreptococcus spp., Gardnerella vaginalis, Mobiluncus spp., Mycoplsma hominis, whose concentrations increase 10-100 times and lead to a decrease in lactobacilli. Risk factors include factors specific to sexually transmitted diseases. Bacterial vaginosis can occur in virgins. It is necessary to treat a sexual partner to prevent recurrence of the disease in sexually active women. The use of intrauterine contraceptives is also a risk factor.

Previously, bacterial vaginosis was considered unimportant. Currently, it is believed that bacterial vaginosis increases the risk of inflammatory diseases of the pelvic organs, promotes the growth of endometritis after abortion or childbirth, vaginal infection after hysterectomy, chorioamnionitis, premature rupture of the membranes of the bladder, premature delivery.

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Risk factors

The risk factors include:

  • frequent douching;
  • promiscuous sexual life or the presence of several sexual partners;
  • systemic antibiotic therapy;
  • use of intrauterine spirals;
  • bathing in public pools and baths.

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Bacterial vaginosis is caused by imbalance of the vaginal microflora with a reduction in the number of lactobacilli (Lactobacillus). Microbiota of bacterial vaginosis was found on the coronary sulcus penis, male urethra. Uncut partners can act as a "reservoir" increasing the likelihood of infection after intercourse. Another mechanism of transmission is contact, skin-to-skin.

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Symptoms of the bacterial vaginosis

Vaginal discharge is fetid, gray, liquid, profuse. Usually, the secretions have a fishy smell, are amplified, becoming abundant and alkaline, after sexual intercourse and menstruation. The most common signs are itching and irritation. Less common are hyperemia and edema.

The leading and often occurring symptoms of bacterial vaginosis are complaints of heavy whites with an unpleasant odor. At the beginning of the disease, whites have a liquid consistency, white or with a grayish hue of color. With a prolonged course of the disease, they acquire a yellowish-green color. Become thicker, often resemble cheesy mass. Have the property of foaming, slightly viscous, sticky, evenly distributed on the walls of the vagina. The amount of whites on average is about 20 ml per day (about 10 times higher than normal). Some patients note local discomfort, a feeling of itching and burning in the vulva, dyspareunia. At an objective inspection it is necessary to pay attention to a condition of external genitals, an external aperture of a urethra, a mucous membrane of a vagina, a neck of a uterus, character of vydeleny. The peculiarity of bacterial vaginosis is the absence of signs of inflammation (edema, hyperemia) of the vaginal walls. Mucous membrane of usual pink color. The colposcopic picture is characterized by the presence of dystrophic changes.

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Complications and consequences

It is possible to develop endometritis, salpingitis, chorioamnionitis, cervicitis of pelvic inflammatory diseases, especially after invasive gynecological procedures.

In pregnant women, as a result of an ascending infection, infection of fetal membranes and amniotic fluid is possible, resulting in spontaneous abortions and premature births. The fetus can become infected both antenatally and intranatally. In the presence of complications of pregnancy in the anamnesis (premature rupture of membranes, birth of a fetus with a low body weight, stillbirth, endometritis, premature birth, prematurity), it is advisable to conduct a study in the period of 12-16 weeks for the diagnosis of bacterial vaginosis.

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Diagnostics of the bacterial vaginosis

For the diagnosis should be present 3 of 4 criteria: gray discharge, pH of vaginal secretions above 4.5, fish odor and the presence of key cells. Key cells are identified microscopically on glass with saline solution (bacteria adsorbed on epithelial cells and shade their edges). When leukocytes are detected on the glass with saline fixation, a concomitant infection such as trichomoniasis, gonorrhea or chlamydia cervicitis can be detected, which will require additional examination.

The diagnosis of bacterial vaginosis can be made on the basis of clinical criteria or in Gram stain. Clinical criteria are determined by the presence of at least three of the following symptoms or signs:

  • Homogeneous, white, adhered on the walls of the vaginal discharge in the absence of signs of inflammation;
  • Presence of key cells during microscopic examination;
  • pH of the vaginal fluid> 4.5;
  • Fish odor of vaginal discharge before or after addition of 10% KOH solution.

When a Gram stain is examined, determining the relative concentration of bacterial morphotypes characterizing the change in microflora is an acceptable laboratory method for diagnosing bacterial vaginosis. A culture test for Gardnerella vaginalis for the diagnosis of bacterial vaginosis is not recommended because it is not specific.

Physical examination for bacterial vaginosis

When viewed in mirrors - the presence of abundant discharge in the absence of signs of inflammation of the vagina.

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Laboratory methods for the study of bacterial vaginosis

  • Microscopic methods are basic. Microscopy is subjected to moist (native) preparations of secretions taken from the anterior wall of the vagina and from the posterior fornix, and also make a smear for staining with methylene blue. Attention is drawn to the characteristics of a vaginal smear for bacterial vaginosis:
    • The absence of leukocytes in the smear or a meager number of leukocytes;
    • absence of lactobacilli or a small number of them;
    • abundant number of bacteria covering the entire field of view: small coccobacteria, cocci, vibrios;
    • presence of "key" cells - cells of the flat vaginal epithelium, covered with a lot of bacteria due to direct adhesion to the cell surface, and also "superadhesion" on the adherent microbial cells.
  • Cultural diagnostics are not used.

The most informative laboratory method for the diagnosis of bacterial vaginosis is the detection in key strokes stained by Gram, of the key cells (the squashed cells of the vaginal epithelium covered with small gram-negative rods). This indicator is revealed in 94,2% of patients, while in healthy women it is not determined. The appearance of key cells in bacterial vaginosis can be associated with dystrophic changes in the mucous membrane of the vagina, increased sloughing of the epithelium, and enhanced adhesion of gram-negative microorganisms to these cells. A great importance in the diagnosis of bacterial vaginosis is pH-metry and aminotest. They refer to screening methods, they can be used directly during an outpatient appointment. In patients, the pH of the vagina is always between 5.0 and 7.5. Aminotest is positive in 83.1% of cases (the appearance or strengthening of an unpleasant smell of rotten fish - isonitride when mixed in equal amounts of vaginal contents and 10% potassium hydroxide solution).

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Treatment of the bacterial vaginosis

Assign vaginal gel 0.75% metronidazole for 5 days or 2% clindamycin in the form of vaginal cream 1 time per day for 7 days. Effectively, the appointment of metronidazole to the gingival is 500 mg 2 times a day for 7 days or 2 g once orally. However, systemic adverse effects can be noted. Women who use clindamycin as cream can not use latex products (such as a condom or diaphragm) for contraception, because the drug weakens latex. Treatment of sexual partners in the absence of symptoms of the disease is not required. With vaginosis during the first trimester of pregnancy, the appointment of a vaginal gel metronidazole; although metronidazole treatment is performed during pregnancy, there is no evidence of a reduced risk of complications of pregnancy. Metronidazole can be prescribed prophylactically before abortion to all patients or only to those who have positive criteria for bacterial vaginosis when examining the vaginal secretion.

The order of the doctor's actions with the diagnosis of bacterial vaginosis

  • The patient is informed of the diagnosis.
  • Present information about sexual behavior during treatment.
  • Gathering of a sexual anamnesis.
  • Discusses with the patient the possibility and necessity of examination for other STIs. Vaccination against hepatitis B has been recommended.
  • Identification of predisposing factors and their elimination.
  • In the absence of results from treatment, the following possible causes should be considered:
    • false positive test result;
    • non-compliance with treatment regimen, inadequate therapy;
    • presence of other predisposing and supporting factors.

A two-stage method of treatment is used, the main principle of which is the creation of optimal physiological conditions of the vaginal environment and the restoration of microbiocenosis. At the first stage of treatment, local antibacterial therapy is performed (metronidazole, clindamycin, levomycetin, etc.), lactic acid is prescribed to lower the pH, laser therapy, immunocorrectors, estrogens, prostaglandin inhibitors and antihistamines according to indications. In the presence of itching, burning, pain, local anesthetics are used. The second stage involves the use of bacterial biological products: lactobacterin, acylactate, bifidumbacterin, bifidin topically to restore the vaginal microflora. The appointment of these drugs without a preliminary first phase is futile because of the pronounced competition between the microorganisms of the vagina. In fact, the introduction of lactic acid bacteria into the vagina is a "transplantation" of these microorganisms, and their "survival" largely depends on the state of local immunity, endocrine status and the presence of risk factors.

The principal goal of therapy is to resolve vaginal symptoms and symptoms. Consequently, all women (non-pregnant and pregnant) who have symptoms are in need of treatment. Bacterial vaginosis during pregnancy is associated with an unfavorable outcome of pregnancy, and some studies show that treatment of pregnant women with bacterial vaginosis and a high risk of preterm labor (ie, those who have had a history) can reduce the number of premature births. Consequently, for asymptomatic pregnant women at high risk, it is advisable to decide on the need for treatment. Some reputable experts recommend treating bacterial vaginosis in pregnant women at high risk, others believe that it is necessary to have more clinical trial data on this issue. Currently, large randomized trials of bacterial vaginosis in asymptomatic women are being conducted, the results of which will determine the benefits of treating bacterial vaginosis in pregnant women with low and high risk.

Many representatives of the bacterial flora that characterizes bacterial vaginosis are excreted from the endometrium or uterine tubes of women with PID. Bacterial vaginosis was associated with endometritis, PID or vaginal cellulitis after such invasive procedures as endometrial biopsy, hysterectomy, hysterosalpingophage, intrauterine device introduction, caesarean section, or curettage of the uterus. The results of a randomized controlled trial showed that treatment of bacterial vaginosis with metronidazole significantly reduces the incidence of postabortion PID. Based on these data, it may be worthwhile to treat bacterial vaginosis (accompanied by symptoms or asymptomatic) before performing surgical abortions. However, further research is needed to address the need to treat asymptomatic women with bacterial vaginosis before performing other invasive procedures.

Recommended regimens for the treatment of bacterial vaginosis for non-pregnant women

Metronidazole 500 mg orally 2 times a day for 7 days.

  • or Clindamycin Cream, 2%, one complete applicator (5 g) intravaginally at night - for 7 days,
  • or Metronidazole gel, 0.75%, one complete applicator (5g) intravaginally-one or two times a day, for 5 days.

NOTE: Patients should be warned that they should avoid drinking alcohol during treatment with metronidazole, and within 24 hours after the end of treatment. Clindamycin cream is oil-based and can damage the structure of latex condoms and diaphragms. For more information, contact companies that produce annotations for condoms.

Alternative treatment regimens for bacterial vaginosis

Metronidazole 2 g orally once or Clindamycin 300 mg orally 2 times a day for 7 days.

Treatment with metronidazole, used in a single dose of 2g, is an alternative regimen because of its lower efficacy in the treatment of bacterial vaginosis.

Oral metronidazole (500 mg twice daily, daily) has been shown in numerous studies to be effective in treating bacterial vaginosis, causing the disappearance of symptoms, improving clinical status and dysbacteriosis. According to the efficacy study in four randomized controlled trials, the overall cure rate at 4 weeks after completion of treatment between the 7-day regimen of oral metronidazole and clindamycin-vaginal cream does not differ significantly (78% and 82%, respectively). Randomized controlled trials also showed that there is no significant difference in the cure between the 7-day regimen of oral metronidazole and metronidazole-vaginal gel after a 7-day treatment (84% and 75%, respectively). The FDA approved the use of Flagyl ER ™ (750 mg) once a day for 7 days to treat bacterial vaginosis.

Some health care providers have doubts about the possible teratogenic effects of metronidazole, which has been confirmed in animal studies using very high doses and long courses of treatment. However, a recent meta-analysis showed no evidence of teratogenicity of metronidazole in humans. Some health workers prefer an intravaginal route of administration, since there is no risk of developing systemic side effects (for example, gastrointestinal disorders are usually mild or moderate, and the drug has an unpleasant taste). The mean peak concentration of metronidazole in serum with intravaginal injection is 2% lower than when using standard oral doses of 500 mg, and the average bioavailability of clindamycin cream is about 4%).

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If the symptoms have disappeared, then there is no need for further monitoring. Relapses of bacterial vaginosis occur quite often. Because the treatment of bacterial vaginosis in asymptomatic pregnant women with high risk can prevent an unfavorable outcome of pregnancy, it is recommended to conduct a follow-up examination one month after treatment to assess the cure. Alternative regimens can be used to treat relapses. Currently, there is no scheme with the use of any drug for long-term maintenance therapy.

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Management of sexual partners in bacterial vaginosis

Clinical trials have shown that treatment of sexual partners does not affect either the effectiveness of treatment performed by a woman or the frequency of relapses, therefore, routine treatment of sexual partners is not recommended.

Bacterial vaginosis and concomitant diseases

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Allergy or intolerance

When allergic to metronidazole or its intolerance should be preferred clindamycin cream. Metronidazole gel can be given to those patients who have intolerance to systemic metronidazole, but patients with an allergy to oral metronidazole can not be administered intra-vaginally.

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Pregnancy and bacterial vaginosis

Bacterial vaginosis is associated with adverse pregnancy outcomes (early rupture of the bladder, prematurity and premature birth), in addition, microorganisms that are found in elevated concentrations in bacterial vaginosis are often secreted in the postpartum endometrium or in the endometrium after caesarean section. Because treatment of bacterial vaginosis in asymptomatic pregnant women at high risk (preterm birth in the anamnesis) can reduce the risk of preterm birth, such pregnant women should be examined and, if bacterial vaginosis is detected, treated. Screening and treatment should be performed at the beginning of the second trimester of pregnancy. Recommended treatment regimen: Metronidazole 250 mg orally 3 times a day for 7 days. Alternative scheme - metronidazole 2 g orally in a single dose or clindamycin 300 mg orally 2 times a day for 7 days.

Pregnant women with low risk (women who do not have a history of preterm labor) with symptoms of bacterial vaginosis should be treated before the symptoms disappear. Recommended scheme: metronidazole 250 mg orally 3 times a day for 7 days. Alternative scheme - metronidazole 2 g orally in a single dose or clindamycin 300 mg orally 2 times a day for 7 days or metronidazole-gel, 0.75%, one complete applicator (5 g) intravaginally 2 times a day for 5 days. Some experts prefer to use systemic therapy for low-risk women in the treatment of possible infections of the upper reproductive tract with subclinical manifestations.

Lower doses of drugs during pregnancy are recommended because of the desire to limit the effects of drugs on the fetus. There are scanty data on the use of metronidazole-vaginal gel during pregnancy. It is not recommended to use clindamycin-vaginal cream during pregnancy, tk. According to two randomized studies, there was an increase in the number of premature births after treatment with clindamycin-vaginal cream.

HIV infection

Persons with HIV infection and bacterial vaginosis should receive the same treatment as patients without HIV infection.

More information of the treatment


Timely correction of hormonal and immunological status, normalization of intestinal microbiocenosis.

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Bacterial vaginosis usually has a favorable prognosis. With inadequate therapy, complications may develop.

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