Bacterial vaginosis

Bacterial vaginosis is caused by pathogenic bacteria in the vagina. They can be transmitted through sexual intercourse. Learn more!

Bacterial vaginosis

The bacterial vaginosis arises when pathogenic bacteria colonize the vagina. These are usually several bacterial strains, with Gardnerella vaginalis accounting for the largest share. They can be transmitted through sexual intercourse, but bacterial vaginosis is only conditionally one of the sexually transmitted diseases. Treatment is with antibiotics. However, relapses often occur. Read all important information about bacterial vaginosis here!

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in doctor's letters or on incapacity certificates. N76

Product Overview

Bacterial vaginosis

  • description

  • symptoms

  • Causes and risk factors

  • Examinations and diagnosis

  • treatment

  • Disease course and prognosis

Bacterial vaginosis: description

The vagina (vagina) is naturally colonized with various bacteria (physiological vaginal flora), mainly with so-called lactobacilli. They produce a certain pH value via their metabolites and in this way protect the female genitalia from colonization with pathogenic agents. However, the condition can change due to several influences. Then multiply pathogenic germs and trigger a bacterial vaginal infection.

In bacterial vaginosis (BV), the number of bacteria that can survive even without oxygen (anaerobes), increases enormously. Since various germs attack the vaginal tissue, it is a mixed infection. By far the largest share is the bacterium Gardnerella vaginalis. This pathogen is detectable in every bacterial vaginosis. That is why some doctors also speak of Gardnerella vaginitis.

Gardnerellen releases more amines. These provide the fishy odor of the vaginal discharge of a bacterial vaginosis. Therefore, bacterial vaginosis is also known as amine vaginosis or aminolpitis. The term colpitis generally describes all inflammations of the vaginal mucosa.

However, not all bacterial vaginal infections cause inflammatory complaints, which is why the value-free term "bacterial vaginosis" prevailed (confirmed in 1984 by a working group of the World Health Organization).

Bacterial vaginosis - occurrence

Gardnerella bacterial vaginosis is the most common bacterial vaginal infection. Affected are mainly sexually mature women aged 15 to 44 years. Bacterial vaginosis is about 2.4 times more common in black women than in white women. In the United States, an estimated 21 million women have BV. In Europe, about 7 to 22 percent of pregnant women are affected and about five percent of women who take precautions. Patients who seek treatment in a clinic for sexually transmitted diseases have a more than 30 percent incidence of bacterial vaginosis. But women without sexual intercourse can also develop an aminolipitis.

Bacterial vaginosis - transmission

The vaginal infection caused by Gardnerella vaginalis and other bacteria involved is not classified as Sexually Transmitted Diseases (STD). Nevertheless, bacterial vaginosis is contagious. It has been found that women with frequently changing or new sexual partners are at increased risk for bacterial vaginosis. Conversely, a bacterial vaginal infection increases the likelihood of developing STD. Although much less common, women who have never had intercourse are also affected by bacterial vaginosis. And although Gardnerella can be detected in many men in microbiological specimens from the urethra, cases were also reported in monogamous homosexual women.

Bacterial vaginosis: symptoms

According to various studies, about 50 to 70 percent of all those affected have no complaints. By far the most common signs of bacterial vaginosis are symptoms of increased fluidity and white-grayish vaginal discharge (vaginal vaginal) with a fishy odor. Amines are responsible for this often unpleasant odor. They arise when Gardnerellen decompose proteins.

Typical signs of inflammation such as redness or pain are absent in most bacterial vaginosis. Therefore, some experts insist that bacterial vaginosis is not automatically an aminolpitis (vaginal inflammation). However, some patients complain of itching and a burning sensation. Rarely, they also report pain during intercourse (dyspareunia). In addition, patients occasionally report discomfort, even on the external genitals (vulva). For example, they feel your vagina, despite the outflow as dry.

The inguinal lymph nodes are swollen in a bacterial vaginosis only in exceptional cases. Problems with urination (dysuria) occur only occasionally.

Bacterial vaginosis: causes and risk factors

To understand the causes of bacterial vaginosis, understanding the normal, healthy vaginal flora is important. The term "divorced flora" stands for all micro-organisms, mainly bacteria, which colonize the vaginal mucosa in healthy women. It consists for the most part of so-called lactobacilli. These bacteria are called after their discoverer also as Döderlein sticks. They produce lactic acid and thus lower the pH to about 3.8 to 4.4 (a neutral pH is 7.0). They also produce hydrogen peroxide and other substances (bacteriocins, biosurfactants).

In addition, other bacteria can be detected, although they can cause disease, but are not represented in sufficient numbers (facultative pathogenic). There are those that need oxygen to live (aerobes) and those that can multiply in the absence of oxygen (anaerobes). For example, Gardnerella vaginalis, the main pathogen of bacterial vaginosis, belongs to the latter type of bacteria. The bacteria are sometimes only temporarily part of the vaginal flora (transient). Still others live permanently on the mucous membrane, but this does not hurt (kommsal).

Function of the vaginal flora

The natural composition of the vaginal flora protects the vagina from pathogenic infections. On the one hand, it is assumed that due to the dense colonization pathogenic germs can no longer penetrate. Their attachment is also prevented by biosurfactant from the Döderlein chopsticks. On the other hand, the low pH and bacteriocins prevent harmful bacteria from growing. However, if the balance of the vaginal flora shifts, its protective function is lost. Previously, only a few occurring pathogens can now spread and eventually lead to vaginal inflammation.

Origin of bacterial vaginosis

In bacterial vaginosis, several anaerobes multiply, most notably the bacterium Gardnerella vaginalis. Its discoverers Gardner and Duke described the bacterium as Haemophilus vaginalis in 1955, which is why this term is still to be found in some works. On average, its exciter number increases one hundredfold. Also other anaerobic germs (eg Prevotella, Mobiluncus) multiply - often by a thousandfold. The mass of lactobacilli decreases, however. For example, in a Washington University study, women were tested for hydrogen peroxide-producing lactobacilli. In healthy women, they were detected to 96 percent. In women with bacterial vaginosis only six percent.

Risk factor of ethnic origin

Studies from the United States of America have shown that the risk of bacterial vaginosis depends on the ethnic background of the women. Most African-American women suffer from bacterial vaginosis, followed by women from Mexico. White women are much less affected. This is explained among other things by different Laktobazillus kinds. Nowadays, for example, Lactobacillus crispatus, L. gasseri, L. iners and L. jensenii are known. Depending on their origin, these occur in varying numbers and thus produce a different pH value.

In some healthy women even no Döderlein chopsticks can be detected. This is the case with about nine percent of white women. In women of Hispanic or African descent, the proportion is already around 30 percent. As a result, there are also significant differences in pH, which can increase to as high as 5.2. This reduces the protective function of the otherwise acidic vaginal flora (pH 3.8-4.4).

Other risk factors

Research has shown that mental stress - independent of other factors - can double the risk of bacterial vaginosis. Deficient or equally exaggerated genital hygiene (vaginal douching) also adversely affects the vaginal flora and thus promotes a bacterial vaginal infection. Pregnancies combined with a vitamin D deficiency are also considered a risk factor. According to further studies, changes in the immune system should contribute to a bacterial vaginosis (eg increased levels of the messenger substance interleukin-1).

In addition, various medications, especially antibiotics, can alter the natural vaginal environment (antibiotics also inhibit "good" bacteria of the vaginal flora). The same applies to impure foreign bodies (for example sex toys). In addition, sex plays a crucial role in the transmission of bacterial vaginosis. The risk increases accordingly by frequently changing sexual partners and unprotected intercourse. However, bacterial vaginosis is not one of the sexually transmitted diseases.

Bacterial vaginosis: diagnosis and examination

If you suspect you have bacterial vaginosis you should consult a gynecologist and gynecologist. A bacterial vaginal infection is confused by many women, for example, with a fungal infection.However, the bacterial vaginosis therapy differs significantly from that in a fungal colonization. Therefore, the presumption should always be clarified by a doctor. At the beginning of the appointment he asks questions about the medical history and current complaints:

  • Have you noticed increased vaginal discharge? If so, what does it look like?
  • Do you feel an unpleasant or even "fishy" genital odor?
  • Do you feel pain, itching or burning in the genital area?
  • Have you had any bacterial vaginal infections in the past, especially an aminolpitis?
  • Was the sexual partner changed frequently? If so, are you looking for safe sex?

Then the doctor examines the body exactly. This includes, in particular, the precise examination of the vagina and the cervix using a speculum. In the case of bacterial vaginosis, a whitish-gray covering of the vaginal mucous membrane can be recognized in particular. The doctor also takes a swab for further tests.

Diagnosis based on the blackbird criteria

According to a study from 1983 and the current German guidelines, the diagnosis "bacterial vaginosis" is based on the so-called Amsel criteria. Three of the following four points should be fulfilled. According to a paper published in 2005, two proven factors are sufficient (the pH value being the most important criterion).

  • Thin, white-greyish, uniform (homogeneous) vaginal discharge
  • Vaginal pH above 4.5 (in about 90 percent of bacterial vaginoses)
  • Detection of at least 20 percent of so-called clue cells under the microscope
  • Positive odor test ("fishy", in about 70 percent of patients with BV)

amine test

At the last point, the doctor also drops 10% potassium hydroxide solution (KOH) on the suspicious mucous membrane or mixes it with the vaginal secretions. Bacterial vaginosis releases even more amine. This fabric produced by the Gardnerellen causes a strong fishy smell. This method of investigation is also known as amintest and whiff-test.

key cells

The term key cells has been used by the Gardnerella discoverers, as they have considered the detection of such "clue cells" as the key to the diagnosis of "bacterial vaginosis". These are superficial cells of the vaginal mucosa (epithelial cells), which are densely covered by bacteria. As a result, the cell boundaries are no longer recognizable. Under the microscope, their shape is reminiscent of breaded schnitzel.

Gram stain

Alternatively or in addition to the blackbird criteria, the physician can detect bacterial vaginosis by means of typical bacterial staining (Gram stain). Named after the Dutch bacteriologist Hans Ch. Gram, one distinguishes Gram-positive (blue-colored) from gram-negative (red-colored) bacterial species. In addition, there are also gram-labile, so unevenly colored stems. Stained is a smear of the vaginal discharge. The investigator counts under the microscope pathogens (gram-negative: Gardnerellen, Atopobien, Prevotellen and Porphyromonas, gram-labile: Mobiluncus) and gram-positive lactobacilli, which usually make up the largest share. Typical of bacterial vaginosis is the enormous increase in pathogens and a marked decrease in lactobacilli (mismatch / dysbalance).

Nugent score

Depending on the determined number of cells, points are then awarded and the result is assessed according to the Nugent score. With a score of more than seven, there is a bacterial vaginosis. As an example, the examiner finds hardly any lactobacilli under the microscope (1000x magnification), which corresponds to three points. However, he finds up to 30 gram-negative anaerobes (eg Gardnerella, 3 points) and more than five Mobiluncus bacteria (2 points). So the doctor receives a total score of eight (3 + 3 + 2 = 8) and thus diagnoses bacterial vaginosis. A sum between four and six counts as unclear result. It is counted in a visual field, ie the image that the doctor sees through the microscope without moving the glass plate.

Points (Score)

Lactobacilli per visual field

Gram-negative Gardnerella and other anaerobes per field of view

gram-labile, curved mobiluncus per visual field



















Cultivation of the bacteria

Gardnerella and other typical anaerobes from vaginal smears can grow on certain nutrient media. Experts speak of a bacterial culture. Nearly all bacterial vaginoses succeed in this cultivation. However, even in 70 percent of symptom-free women. Therefore, this study has little meaning these days. In unclear cases of bacterial vaginal inflammation (especially during pregnancy) or when the treatment of bacterial vaginosis fails, physicians still resort to this diagnostic tool.

Distinction to other vaginal diseases (differential diagnosis)

Bacterial vaginosis is sometimes confused with other diseases of the vaginal mucosa. These include, for example, the vaginal inflammation caused by trichomonads or a colonization with yeasts (candidiasis).The doctor will distinguish these diseases from bacterial vaginosis through his investigations, which is crucial for successful treatment. The table shows the most important differences:

bacterial vaginosis

Trichomonas infection

Vaginal candidosis (yeast fungus)

annoying vaginal odor

yes, fishy




thin, white-gray, even

green-yellowish, z.T. frothy

whitish, crumbly

Irritations of the vulva

sometimes, but hardly any redness



Pain during sex

rather no



typical cells (determined microscopically)

key cells

Agile flagellates (flagellates)


PH value

> 4,5

> 4,5

normal (<4.5)





smell test


can be positive


Bacterial vaginosis: treatment

Bacterial vaginosis therapy is necessary if the patient has symptoms (such as increased and foul-smelling discharge) and the doctor has confirmed the diagnosis using the Amsel criteria. Complaint-free patients do not need to be treated. The same applies if gneratory cells (or other anaerobes) are detected in a bacterial culture but the patients do not suffer from any bacterial vaginosis symptoms.

Treat bacterial vaginosis

If the doctor wants to treat bacterial vaginosis, he prescribes antibiotics. The drug of choice is metronidazole (or tinidazole, also from the nitroimidazole group). This is prescribed either as a tablet (2x500mg / day for 7 days or once 2g or 2x2g within 48 hours) or as a 0.75% vaginal gel. In addition, bacterial vaginosis can be treated with a 2% clindamycin vaginal cream (5g, daily for one week). Vaginal tablets containing nifuratel (daily 250 mg for 10 days) or dequalinium chloride (10 mg daily for 6 days) can also be used for bacterial vaginosis therapy.

Problem bacterial biofilm

The symptoms and also the pH value normalize through the therapy with the mentioned medicines (metronidazole, clindamycin, nifuratel, dequalinium). However, bacterial vaginosis is rarely completely cured. In most cases, a so-called bacterial biofilm remains on the vaginal mucosa. It is a thin layer on the superficial sheath cells, consisting mainly of Gardnerella and Atopobia. Atopobium vaginae is an anaerobic bacterium that was discovered in 2006 and is resistant to metronidazole. Due to this biofilm, bacterial vaginoses can germinate (recur) again and again.

Bacterial vaginosis - home remedies

Some patients use various natural products to treat the symptoms of bacterial vaginosis. These include, for example, milk, black tea or oregano oil, which are introduced into the vagina via a tampon. Also garlic, wrapped in gauze and introduced, is to help against the Aminkolpitis. Tea tree oil and vinegar or lemon water are also common bacterial vaginosis home remedies. Furthermore, probiotic yoghurts and vitamin C (ascorbic acid) should be able to restore the normal vaginal flora (studies have shown an unknown relationship between the colonization of the digestive tract and the vaginal flora).

However, none of these natural active ingredients are currently listed as suitable bacterial vaginosis therapy in the currently validated lines. However, the experts agree that the intake of certain lactobacilli strains (via vaginal suppositories) or acidic medications (azides, which lower the vaginal pH again) may lower the relapse rate. In some specialist literature, the use of vitamin C tampons is considered promising. Some doctors also recommend disinfecting vaginal lavages or suppositories (such as povidone-iodine).

Bacterial vaginosis - pregnancy

The bacterial vaginosis of pregnant women is always treated. Because the germs can rise above the cervix. As a result, they increase the risk of premature rupture of membranes, premature labor or premature birth. Bacterial vaginosis therapy can be given after the first three months as in non-pregnant women using metronidazole tablets. Alternatively, doctors prescribe metronidazole (0.5-1g daily for one week) or clindamycin vaginal creams (over a week) for local vaginal use. In women who have had premature birth, systemic therapy with tablets is recommended (but only after the 1st trimester, as they may damage the embryo, previously only locally).

No co-treatment of the partner

According to studies, as many as 80 percent of the male sex partners of women with bacterial vaginosis also Gardnerellen. These can be detected in urine, sperm and urethral swab. However, unlike sexually transmitted diseases such as chlamydia, they do not need to be treated with medication. Various studies have shown that bacterial vaginosis therapy is more successful in partner treatment. However, the recurrence rate (recurrence) is just as high as in women whose sex partners are not treated. Even the current guidelines do not recommend routine treatment of the partners.

Bacterial vaginosis: disease course and prognosis

Bacterial vaginosis causes no symptoms in many cases. If it comes to disease symptoms, they can be alleviated by taking antibiotics. A definitive cure is achieved only in the fewest cases. Although bacterial vaginosis is usually uncomplicated, it significantly increases the risk of further infection, including HIV infection.

Ascending infection

Like other pathogens of the genital area (e.g., chlamydia, gonococci), the germs of bacterial vaginosis (or its subsequent infections) may spread. They ignite, for example, the external female genitalia (vulva) and the vaginal atrial gland (Bartholin gland). The bacteria may migrate from the cervix into the uterus and eventually through the fallopian tubes to the ovaries. On their way they can colonize the mucous membrane and cause inflammation. Doctors in this case speak of an ascending (ascending) infection. Possible clinical pictures that can follow bacterial vaginosis are:

  • vulvitis
  • Salpingitis, pelvic inflammatory disease (inflammation of the fallopian tubes and ovaries)
  • Tubo-ovarian abscess (collection of pus in the fallopian tubes / ovaries)
  • Endometritis (inflammation of the endometrium)
  • Cervicitis (inflammation of the cervix)

Incidentally, Gardnerella vaginalis very rarely affects the whole body (systemic infection). In isolated cases heart valves (endocarditis) or meningitis have been described. After a bacterial vaginosis pregnancy, some mothers suffered from bacterial sepsis during the puerperium (also extremely rare).

Complications after medical intervention

The risk of ascending bacterial colonization continues to increase when medical interventions are performed (iatrogenic infection). They damage the mucosal cells and thus promote an infection. In particular, inserting a "spiral" (IUD, intrauterine device) or a termination of pregnancy favor that the pathogens of bacterial vaginosis can migrate upwards. Therefore, experts recommend that affected individuals be screened for bacterial vaginosis prior to such surgery.

Surgery in the lower abdomen, especially on the female genitals, also increases the risk of severe pelvic infection in the pelvis after bacterial vaginosis (pelvic inflammatory disease). For this reason, for example, doctors administer antibiotics before, during and after vaginal hysterectomy (vaginal hysterectomy). Among other things, they want to prevent the remaining vaginal stump from becoming inflamed.

Bacterial vaginosis-pregnancy complications

Research groups from the US and Germany have shown that bacterial vaginosis can lead to problems, especially in the last months of pregnancy. Ascending germs trigger different reactions both in the fetus and in the maternal defense system. As a result, so-called prostaglandins are increasingly being produced. These messengers are involved, for example, in pain mediation and inflammation.

The prostaglandins also ensure that the uterine muscles contract (important in the birth process). In addition, it increases the number of metalloproteases (enzymes from proteins). For example, these proteins can cause a premature rupture of the bladder. Furthermore, the pathogens of bacterial vaginosis can infect the amniotic fluid or the egg skin (amnion, part of the inner amniotic sac) and lead to serious infections of the mother (bacterial septicemia = puerperal sepsis) and the child. Aminkolpitis may therefore be the cause

  • premature labor
  • a premature rupture of membranes
  • a premature birth
  • an amnionitis, amniotic infection syndrome
  • Infections of the newborn
  • Inflammatory wound healing disorders in the mother after dam or caesarean section (eg abdominal abscess)

Bacterial vaginosis - prevention

There is no definite tip for prevention. As with all diseases that can be transmitted sexually, Safer Sex protects against infection, especially if you change your sexual partners frequently. Also, avoid potential risk factors such as stress or excessive vaginal hygiene. It is best to use normal soap (hypoallergenic, fragrance-free or similar) and no special vaginal care products. The guidelines also support probiotic vaginal suppositories with lactobacilli against relapses of bacterial vaginosis.

Pregnancies should be given special attention. Consult your gynecologist for bacterial vaginosis. This usually performs the necessary examinations in the context of prenatal care and checks the success of the treatment after an infection. However, there is no screening for bacterial vaginosis paid by the health insurance companies. The Erfurt premature birth prevention campaign achieved promising results. Many pregnant women have determined their own pH (increased in 90 percent of BV). Consequently, premature birth risk factors such as bacterial vaginosis could be treated in time.

For example, for the pH self-test there are special gloves with a test strip. This is inserted a few centimeters into the vagina and shows after a short time the pH. A result above 4.5 may indicate bacterial vaginosis. In this case, make an appointment with your gynecologist. This can exclude suspicion by further investigations or the bacterial vaginosis to treat.

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