Bacterial vaginosis

and Martina Feichter, medical editor and biologist Updated on

Florian Tiefenböck studied human medicine at the LMU Munich. In March 2014, he joined as a student and has supported the editorial team with medical articles ever since. After receiving his medical license and practical work in internal medicine at the University Hospital Augsburg, he has been a permanent member of the team since December 2019 and, among other things, ensures the medical quality of the tools.

Brief overview

What is bacterial vaginosis? Disturbance of the balance of the natural vaginal flora through the multiplication of potentially disease-causing germs, thereby displacing the "good" bacteria.
Symptoms: Often none. In other cases especially thin, grayish-white discharge that smells unpleasant ("fishy"). Occasionally signs of inflammation such as redness, burning and itching. Possibly also pain during sex or urination.
Causes and risk factors: sexual intercourse (especially with new or frequently changing sexual partners), excessive intimate hygiene, use of vaginal products, smoking, pregnancy, lack of estrogen, use of antibiotics, psychosocial stress, ethnic factors, possibly vitamin D deficiency
Diagnosis: gynecological examination, smear (on this, pH value determination, detection of "key cells")
Treatment: Necessary in case of symptoms and during pregnancy. Usually antibiotics are given, which can be applied locally and orally (as tablets).
Prognosis: Sometimes bacterial vaginosis heals on its own. Treatment is usually successful, but the risk of relapse is high.
possible complications: other gynecological infections (such as cervical inflammation), especially with medical interventions; increased risk of venereal diseases; Slightly increased risk of premature birth and other complications during pregnancy.

Bacterial vaginosis: description

Bacterial vaginosis (BV) is an imbalance in the composition of the bacteria naturally living in the vagina (physiological vaginal flora) - potentially pathogenic germs have gained the upper hand and suppressed "good" bacteria.

The vagina is naturally colonized with various bacteria, mainly with rod-shaped lactobacilli (also called lactic acid bacteria or Döderlein rods after their discoverer). Through their metabolic products, they create an acidic environment (low pH value) in the vagina, in which pathogens that cause disease can hardly or not at all multiply.

However, various influences can disturb the natural vaginal environment, so that potentially disease-causing bacteria multiply and displace the "good" Döderlein bacteria. Depending on the patient, they probably form a biofilm on the vaginal wall consisting of different germs - bacterial vaginosis has developed.

In the vast majority of patients, this biofilm of potentially pathogenic germs primarily consists of the bacterium Gardnerella vaginalis. This is why some doctors speak of Gardnerella vaginitis, although other types of bacteria are typically also involved in bacterial vaginosis.

Gardnerelles increasingly release amines. These substances create the fish-like odor of vaginal discharge in affected women. This is why bacterial vaginosis is also known as amine vaginosis or amine colpitis. The term colpitis generally describes inflammation of the vaginal mucosa.

Basically, bacterial vaginosis is a bacterial vaginal infection because it causes bacteria to multiply in the vagina that are normally only found sporadically. However, because only some of the women affected develop inflammatory complaints, the neutral term "bacterial vaginosis" finally prevailed (confirmed in 1984 by a working group of the World Health Organization).

No venereal disease

The vaginal infection with Gardnerella & Co. is not one of the classic sexually transmitted diseases (STD). For some years now, experts have been discussing the possibility of sexual transmission more and more. This assumption is supported by the fact that same-sex couples have the same bacterial vaginosis in up to 90 percent of the cases.

So bacterial vaginosis could be contagious. However, many experts do not consider the transmission of individual bacteria (such as Gardnerella) to be decisive, but rather an entire biofilm of potentially disease-causing bacteria.

Bacterial vaginosis: frequency

Bacterial vaginosis is the most common type of vaginal infection. In Europe, it is estimated that five in ten women of fertile age are affected. The proportion among pregnant women is 10 to 20 percent. Among women who are treated in a clinic for a sexually transmitted disease, bacterial vaginosis can also be detected in over 30 percent.

Bacterial vaginosis: symptoms

Bacterial vaginosis is very often asymptomatic: around half of the women affected have no symptoms whatsoever.

If bacterial vaginosis causes symptoms, it is primarily an increased, thin or foamy discharge (fluor vaginalis / genitalis) that is gray-whitish in color and smells noticeably "fishy". Amines are responsible for this odor, which is often perceived as unpleasant. They arise when Gardnerella - the most important germs in bacterial vaginosis - break down proteins. Often times, the fishy smell intensifies after sex and during menstruation.

Typical signs of inflammation such as redness, burning or itching are usually absent. As a result, some experts insist that bacterial vaginosis is not necessarily bacterial vaginitis.

Occasionally, affected women report painful intercourse (dyspareunia) or urination (dysuria). The inguinal lymph nodes are swollen in bacterial vaginosis only in exceptional cases.

Bacterial vaginosis: causes and risk factors

Bacterial vaginosis is caused by an unbalanced vaginal flora. As a result, germs that can cause disease can spread.

The healthy vaginal flora

The term "vaginal flora" stands for all microorganisms (mainly bacteria) that colonize the vaginal mucosa in healthy women. A healthy vaginal flora consists largely of lactobacilli (Döderlein sticks). They produce lactic acid and thus ensure an acidic environment in the vagina (pH value around 3.8 to 4.4). It is difficult for other germs to multiply or even to survive in them.

In addition, other bacteria can be detected in the natural vaginal flora, which can cause diseases but are not represented in sufficient numbers (facultative pathogenic).These include Gardnerella vaginalis and other bacteria that are sometimes only temporarily part of the vaginal flora (transient) or live permanently on the mucous membrane, but do not damage it (commensal).

Function of the vaginal flora

The natural composition of the vaginal flora protects the vagina from pathogenic infections. It is assumed that pathogenic germs cannot spread due to the dense colonization with lactobacilli.

Lactobacilli also produce certain substances (biosurfactants) that prevent other germs from adhering to the vaginal mucous membrane. In addition, some lactic acid bacteria form other substances such as hydrogen peroxide or bacteriocins - these also inhibit the growth of unfavorable germs.

If the number of protective lactobacilli decreases, the balance of the vaginal flora shifts: this destroys the natural protection. Unwanted microorganisms in the vagina can now spread and multiply unhindered and cause various vaginal infections.

Development of bacterial vaginosis

In bacterial vaginosis, different types of bacteria multiply. So there is usually a mixed bacterial infection. Gardnerella vaginalis is almost always involved. Its discoverers Gardner and Duke named the bacterium Haemophilus vaginalis in 1955, which is why this term can still be found in some works.

Other germs that spread strongly in bacterial vaginosis are, for example, Prevotella or Mobiluncus. These are typically bacteria that do not need oxygen to live (so-called anaerobes).

The amount of lactobacilli, on the other hand, decreases. In a study by the University of Washington, women were examined for hydrogen peroxide-producing lactobacilli. 96 percent of them were detected in healthy women. In women with bacterial vaginosis, only six percent.

Risk factors for bacterial vaginosis

The exact processes that cause bacterial vaginosis are not yet fully understood. However, some risk factors are suspected to favor the decline in protective lactobacilli:

Sexual intercourse is probably the single most important factor in causing bacterial vaginosis. Women with a new sexual partner and those with frequently changing sexual partners are particularly at risk.

But there are other factors that can unbalance the natural vaginal flora. Inadequate or excessive intimate hygiene (e.g. frequent vaginal douching) and the use of products that are not adapted to the vaginal environment (cosmetics, scented sprays, etc.) promote bacterial vaginosis. Pregnancy or bleeding during pregnancy can also disturb the balance of the vaginal flora. A deficiency in vitamin D could also contribute to the development of bacterial vaginosis, especially in pregnant women (but also in other women).

Confirmed risk factors are estrogen deficiency, such as occurs during the menopause or in the puerperium, smoking and the use of antibiotics. The latter can act as bacteria-inhibiting or killing drugs and can damage the "good" bacteria in the vaginal flora. This means that after antibiotic therapy (for example in the form of tablets or infusions, i.e. systemically), potentially unfavorable germs can spread more easily.

Psychosocial stress is also considered to be a significant risk factor. It can - regardless of other factors - significantly increase the likelihood of a bacterial vaginal infection.

Ethnic origin also has an important influence on the occurrence of bacterial vaginosis: For example, studies from the USA have shown that African American women are most likely to suffer from bacterial vaginosis, followed by Hispanic women. White American women, on the other hand, are affected much less often.

This can be explained as follows: Depending on the ethnic origin, another type of lactobacilli dominates the vagina (e.g. Lactobacillus crispatus, L. gasseri). Or there are no lactobacilli at all in the healthy vaginal flora, which is more common in African-American and Hispanic women (approx. 30 percent) than in white American women (approx. 9 percent).

These ethnic differences in the composition of the natural vaginal flora result in a significantly different normal pH value - it fluctuates between 3.8 and 5.2 depending on the ethnic group. The higher values are typically found in women of Afro-American and Hispanic origin, which is why they are more often affected by bacterial vaginosis (higher pH value = less acidic and therefore more beneficial for disease-causing bacteria).

Bacterial vaginosis: diagnosis and examination

If you suspect you have bacterial vaginosis, you should consult a specialist in gynecology and obstetrics (gynecologist). Some sufferers confuse a bacterial vaginal infection with a fungal infection (vaginal thrush) and use over-the-counter anti-fungal agents from the pharmacy. However, the recommended therapy for bacterial vaginosis is different than for a fungal infection.

Medical history and gynecological examination

First, the doctor will take your medical history (anamnesis) by asking you various questions, for example:

Have you noticed an increase in vaginal discharge? If so, what does it look like?
Have you noticed an unpleasant or even "fishy" genital odor?
Do you feel pain, itching or burning in the genital area?
Have you had bacterial vaginal infections in the past?
Do you change sexual partners more often? If so, do you pay attention to safe sex (e.g. by using condoms)?

The doctor then examines your genital area, especially the vagina (with the help of a speculum). He also takes a sample (smear) of the vaginal secretion for further examinations.

Diagnosis based on the Amsel criteria

When making a diagnosis, the doctor relies on the so-called Amsel criteria:

thin, white-grayish, uniform (homogeneous) vaginal discharge
Vaginal pH above 4.5 (in about 90 percent of bacterial vaginoses)
At least 20 percent of "key cells" (clue cells) in the microscopic examination of the cells on the surface of the vaginal wall (epithelial cells): These cells are so densely covered by a carpet of different bacteria (biofilm) that the cell boundaries are no longer recognizable .
"Fishy" smell of vaginal discharge (in about 70 percent of patients with BV): The fishy smell is increased by dripping on ten percent potassium hydroxide (KOH) (amine test or "whiff test").

At least three of the four criteria must be met for the doctor to diagnose bacterial vaginosis.

Nugent Score

As an alternative or in addition to the Amsel criteria, the doctor can use the Nugent score to detect bacterial vaginosis. The bacteria in the vaginal secretion sample are subjected to a specific staining method (Gram staining) in order to distinguish "good" from "bad" germs and then to count them.

Gram stain

With Gram staining (named after the Dutch bacteriologist Hans Ch. Gram), the smear of the vaginal secretion is stained with certain substances. Existing bacteria subsequently take on a different color depending on the structure of their cell wall - either a blue color (then referred to as gram-positive) or a red color (gram-negative) or a non-uniform color (gram-labile or gram-variable) . Under the microscope at 1000x magnification, the following types of bacteria (bacterial morphs) can be distinguished:

large gram-positive rods (type Lactobacillus species)
small gram-variable rods (Gardnerella vaginalis type)
small gram-negative rods (type Bacteroides species / Prevotella)
sickle-shaped or curved gram-variable rods (type Mobiluncus species)

In a healthy vaginal flora, the blue-colored (gram-positive) lactobacilli make up the largest proportion. Typical of bacterial vaginosis is the enormous increase in potential pathogens with their red or inconsistent coloration with a simultaneous clear decrease in the number of blue-colored lactobacilli.

Quantitative evaluation

In the next step, the number of three groups of bacteria per field of vision (= section that the doctor sees through the microscope without moving the glass plate) is determined - those of the large gram-positive rods (lactobacilli), those of the small gram-variable or gram -negative rods (Gardnerella, Bacteroides, Prevotella) and those of the sickle-shaped / curved gram-variable rods (Mobiluncus). In each group, points are awarded depending on the number of cells determined, which are then added to the total score. This is interpreted as follows:

Total score between 0 and 3: normal vaginal flora
Total score between 4 and 6: unclear result
Total score between 7 and 10: bacterial vaginosis

In some European countries such as Germany, the Nugent Score is only rarely used, among other things because the necessary work steps (Gram staining, microbiological evaluation under the microscope) are quite complex.

Growing the bacteria

Gardnerella and typical anaerobes can grow on certain nutrient media. If you apply a vaginal swab on such floors, you can cultivate the bacteria contained in it (bacterial culture) and thus identify the different species. This cultivation succeeds in almost all bacterial vaginoses - but also in 70 percent symptom-free women. Further disadvantages of bacterial cultivation: It is quite time-consuming and makes little sense because of the large number of germs that may be involved in bacterial vaginosis.

For this reason, cultural evidence only plays a role in special cases - for example if certain specific germs are suspected (e.g. B-streptococci in pregnancy) or if the treatment of bacterial vaginosis fails, i.e. the normal vaginal flora does not return despite therapy.

Differentiation from other vaginal diseases (differential diagnosis)

Bacterial vaginosis is sometimes confused with other diseases of the vaginal mucosa. These include, for example, vaginal inflammation caused by trichomonads and a vaginal infection with yeast (vaginal candidiasis). The doctor must take this into account in his examinations in order to be able to make the correct diagnosis - the various diseases are treated differently.

The following table shows the most important differences between bacterial vaginosis, trichomonas infection and vaginal thrush:

	bacterial vaginosis	Trichomonads infection	Vaginal candidiasis (yeast)
annoying vaginal odor	yes, fishy	possible	no
discharge	thin, white-gray, even	green-yellowish, partly frothy	whitish, crumbly
Irritation of the vulva	sometimes, but hardly any redness	Yes	Yes
Pain during sex	possible	Yes	Yes
typical cells (determined microscopically)	Key cells	agile flagellates	Pseudohyphae and Sprout Cells
PH value	> 4,5	> 4,5	normal (<4.5)
Lactobacilli	reduced	reduced	normal

The clinical symptoms of a vaginal infection are very diverse and, depending on the pathogen and the female immune or hormone status, can be very different, similar to one another or even completely absent. A medical examination is required to find out the exact cause.

Bacterial vaginosis: therapy

Therapy is generally only initiated when the diagnosis of "bacterial vaginosis" has been confirmed and the patient has symptoms (e.g. increased, foul-smelling discharge). If the diagnosis is unclear and / or there are no symptoms, however, no treatment is necessary. But there are exceptions:

For example, bacterial vaginosis during pregnancy is treated even if the symptoms are absent, because the risk of a miscarriage due to the bacterial infection is increased. In addition, symptom-free BV should be treated if a gynecological procedure is planned (e.g. insertion of the IUD).

Treat bacterial vaginosis

The doctor usually treats bacterial vaginosis with antibiotics, preferably metronidazole or clindamycin. Vaginal cream, suppositories, tablets and tablets for swallowing are available as dosage forms. Depending on the active ingredient, dosage form, dosage and severity of the symptoms, the treatment lasts one to seven days. In general, it works well, as studies have shown. However, relapses often occur after the end of therapy.

Important: Only take antibiotic agents if and how you have discussed this with your doctor. Incorrect use can impair the success of the therapy. In addition, the germs may become more resistant, which makes future treatments more difficult.

Sometimes in bacterial vaginosis, germicidal (antiseptic) agents such as dequalinium chloride or octenidine are used locally instead of antibiotics. According to clinical studies, the first treatment in particular is successful. In some cases, however, the effect of the treatment does not last for a long time here either. Overall, the scientific data on the use of antiseptics in bacterial vaginosis is limited.

Occasionally, bacterial vaginosis is treated with other preparations, such as those containing lactic acid bacteria. How effective these are is difficult to say - lactic acid supplements are less well researched than antibiotics, especially since they are mostly used in combination with them (and not alone).

Bacterial biofilm problem

Treatment can usually eliminate symptoms of bacterial vaginosis and normalize vaginal pH. The biofilm of various bacteria on the surface of the vaginal mucous membrane can usually not be (completely) dissolved with it. This can cause bacterial vaginosis to sprout (relapse) over and over again.

Bacterial Vaginosis - Home Remedies

Some patients use various natural products for the symptoms of bacterial vaginosis. These include, for example, tampons soaked with milk, black tea, tea tree oil or natural yogurt that are inserted into the vagina. Garlic, wrapped in gauze and placed in it, is also said to help against amine colpitis. Vinegar or lemon water are also popular home remedies for bacterial vaginosis that are used topically.

However, it has not yet been investigated whether such home remedies are effective and safe. In addition, some home remedies have certain risks. Sharp substances such as vinegar, for example, can disrupt the vaginal environment and additionally irritate the mucous membrane. Or germs can also get into the vagina, especially with contaminated agents.

Bacterial vaginosis - pregnancy

Bacterial vaginosis in pregnant women is always treated, even when there are no symptoms of the disease. Because the germs can (as with other vaginal infections) rise via the cervix and, among other things, easily increase the risk of premature labor, premature birth and miscarriage.

The treatment can generally be carried out with the same active ingredients as for non-pregnant women (antibiotics, antiseptics). Which preparation is particularly suitable depends, among other things, on the stage of pregnancy. Doctors cannot use every drug unrestrictedly in pregnant women.

Medical guidelines recommend antibiotic treatment for pregnant women. Local treatment with clindamycin (e.g. as a cream) is possible in every phase of pregnancy. From the second trimester of pregnancy (2nd trimester), metronidazole can also be applied locally (earlier in exceptional cases). Systemic therapy with tablets (e.g. metronidazole, clindamycin) is also only recommended from the 2nd trimester (earlier if necessary).

No co-treatment of the partner

Studies have shown that the majority of male sex partners of women with bacterial vaginosis also have Gardnerella. These can be detected in urine, semen and urethral swabs. However, unlike sexually transmitted diseases such as chlamydia, sexual partners generally do not need to be treated with bacterial vaginosis. Studies have shown that this would have a positive effect neither on the cure rate nor on the relapse rate (recurrences).

The same applies to homosexual couples: Co-treatment of the sexual partner is generally not indicated.

Bacterial vaginosis: disease course and prognosis

Bacterial vaginosis heals on its own about a third of the time. If it causes symptoms or if the patient is pregnant, she should be treated. In the majority of cases, the therapy is successful.

However, the risk of relapse is high, especially if an existing biofilm, i.e. the layer of mucus in which the bacteria are embedded, could not or not completely be eliminated by the antibiotics. This is why up to 60 percent of patients develop bacterial vaginosis again within six months after completing therapy

In addition, bacterial vaginosis can lead to various complications:

Risk of further infections
Complications in Pregnancy

Bacterial vaginosis: risk of further infections

Women with bacterial vaginosis are at increased risk of other gynecological infections. The germs of BV can spread, so that the external female genitalia (vulva) or the paired vaginal vestibule (Bartholin's gland) become inflamed.

There is also the risk of an ascending (ascending) infection: The bacteria from the vagina can migrate through the cervix into the uterus and even further up the fallopian tubes to the ovaries. Anywhere along the way, they can colonize the mucous membrane and cause inflammation.

Bacterial vaginosis can therefore result in the following symptoms as the germs spread or rise:

Vulvitis (inflammation of the external female genitals)
Bartholinitis (inflammation of the Bartholin's glands)
Cervicitis (inflammation of the cervix)
Endometritis (inflammation of the lining of the womb)
Salpingitis (inflammation of the fallopian tubes)
Adnexitis (combined inflammation of the fallopian tubes and ovaries)
Tubo-ovarian abscess (accumulation of pus in the area of the fallopian tubes or ovaries)

Gardnerella vaginalis, by the way, very rarely affects the whole body (systemic infection). Heart valve (endocarditis) or meningitis have been described in individual cases.

Increased risk during medical interventions

The risk of ascending infections is also increased if a medical intervention is carried out. This is because mucous membrane cells are damaged, which promotes infestation with germs. For example, inserting an IUD (IUD, intrauterine device) for contraception or an abortion can cause the germs of bacterial vaginosis to rise.

Therefore, experts recommend routinely screening women for bacterial vaginosis prior to such procedures. If this is proven, it should be treated before the procedure if possible.

Risk of STDs

Bacterial vaginosis not only increases the risk of further infections from "its own" germs - it also promotes the colonization of other germs. Women with BV are more prone to STDs (sexually transmitted diseases) such as chlamydia, trichomonas, and gonorrhea.

Bacterial vaginosis & pregnancy: complications

Research groups from the USA and Germany have shown that bacterial vaginosis can lead to problems, especially in the last few months of pregnancy. Rising germs can trigger various reactions in both the fetus and the maternal immune system. As a result, so-called prostaglandins are increasingly produced. These messenger substances are involved, for example, in the mediation of pain and inflammation.

The prostaglandins also ensure that the uterine muscles contract (important during the birth process). They also increase the number of metalloproteases (enzymes made from proteins). These proteins can, for example, cause the bladder to rupture prematurely.

Furthermore, the pathogens of bacterial vaginosis can infect the amniotic fluid or the membrane (amnion, part of the inner amniotic sac) and lead to severe infections of the mother (bacterial blood poisoning in the puerperium = puerperal sepsis) and the child.

So bacterial vaginosis during pregnancy increases the risk of:

premature labor
premature rupture of the urine
Premature birth or miscarriage
Amnionitis, amniotic infection syndrome
Infections of the newborn
inflammatory wound healing disorders in the mother after perineum or caesarean section (e.g. abdominal wall abscess)

Bacterial vaginosis: prevention

There is no reliable tip for prevention. In principle, safer sex is recommended for prophylaxis for all diseases that can be sexually transmitted, such as the use of condoms. This is particularly advisable if you have frequently changing sexual partners.

Also reduce or eliminate possible risk factors - especially if you have already had bacterial vaginosis. For example, you should avoid or reduce stress (e.g. through sport, targeted relaxation exercises) and refrain from smoking.

You should also avoid excessive intimate hygiene. This means, for example: no vaginal douching and no cleaning of the genital area with other aids or auxiliaries.

The local application of lactobacillus, lactic acid or other acid preparations can help to maintain the normalization of the vaginal flora and to prevent a relapse after professional treatment of bacterial vaginosis.

Special tips for pregnant women

Special attention should be paid to pregnancies. Consult your gynecologist about bacterial vaginosis. This usually carries out the necessary examinations as part of prenatal care. However, there is no official screening for bacterial vaginosis.

The Erfurt and Thuringian premature birth prevention campaign 2000 achieved promising results. The participating pregnant women measured the pH value in their vagina themselves twice a week. If the reading was above 4.4, a medical examination for bacterial vaginosis was carried out. If the diagnosis was confirmed, antibiotic treatment was initiated. In this way, the premature birth rate could actually be reduced for the duration of the study.

For the pH self-test, for example, there are special gloves with a test strip. This is inserted a few centimeters into the vagina and after a short time shows the pH value. If the pH value is high, you should see your gynecologist to clarify the suspicion of bacterial vaginosis.

Tags: hospital pregnancy skin care