The healthy vaginal flora of a sexually mature woman consists mainly of different types of lactic acid bacteria (lactobacilli). They are also known as Döderlein bacteria after the German gynecologist Albert Döderlein. These bacteria normally create an acidic environment in the vagina with a pH value of 3.8 to 4.4, which suppresses the proliferation of pathogenic germs.
In the case of bacterial vaginosis, however, the "good" lactic acid bacteria are displaced by pathogenic germs. These mainly include the bacterial species Gardnerella vaginalis, but also
- chlamydia,
- mycoplasma and
- Bacteroides bacteria.
This leads to excessive colonization of the vagina with pathogenic bacteria. The number of lactic acid-producing lactobacilli decreases and the pH value of the vaginal flora rises to around 5. This causes an imbalance in the vaginal environment, resulting in the clinical picture of "bacterial vaginosis".
Incorrect vaginal hygiene is a particular risk factor. Find out below how you can prevent the disease.
Bacterial vaginosis does not necessarily cause symptoms. In around 40 to 50 percent of cases, bacterial vaginosis is asymptomatic, i.e. the women affected are symptom-free.
Otherwise, around half of patients complain of increased vaginal discharge (vaginal fluoride). It is thin, sometimes foamy and has a grey-white to yellowish color. In addition, it usually smells unpleasantly fishy, sometimes sweetish.
In some cases, the unpleasant fishy odor also occurs without the accompanying discharge. Other women, on the other hand, report increased discharge, while the fishy odor is absent.
Those affected find the fishy intimate odor in particular very stressful and unpleasant.
It has nothing to do with a lack of intimate hygiene. Rather, it is caused by the fact that the causative pathogens of bacterial vaginosis break down certain proteins into so-called amines.

Bacterial vaginosis is the excessive infestation of the vagina with pathogens © Kateryna_Kon | AdobeStock
Symptoms such as
- itching,
- burning sensation,
- redness and
- skin irritation
in the external vaginal area are rather atypical for bacterial vaginosis. However, they can also occur in rare cases.
In addition, symptoms such as
- slight stinging pain and
- problems during sexual intercourse or urination
are also possible.
The gynecologist will carry out a gynecological examination to make a diagnosis. This involves taking a swab from the woman's vagina and then carrying out a series of tests and examinations.
These include
- the pH examination,
- the amine test,
- cytological examination under the microscope to assess the vaginal cells and
- the creation of a bacterial culture.
Bacterial vaginosis is present if at least three of the following four findings can be determined:
- There is an increased thin to foamy and gray-white to yellow homogeneous vaginal discharge (fluor vaginalis).
- The pH value of the vaginal flora (vaginal flora) is greater than 4.5.
- The vaginal discharge smells fishy (amine odor).
- In the vaginal smear, so-called clue cells can be detected in at least 20 percent of the vaginal cells.
pH test for the diagnosis of bacterial vaginosis
The pH value can be easily determined using tweezers and a pH indicator strip.
There are also special gloves available from pharmacies. This makes it easy to determine the pH value at home.
Amine test for the diagnosis of bacterial vaginosis
The so-called amine test, also known as the "whiff test", can be used to better assess the fishy odor. To do this, the doctor first takes a swab from the vagina.
He then drips one to two drops of a ten percent potassium hydroxide solution onto the swab material. The typical fishy smell of the vaginal discharge is intensified by the potassium hydroxide solution. This allows the doctor to draw better conclusions about the presence of bacterial vaginosis.
Cytological examination for the diagnosis of bacterial vaginosis
As part of the cytological examination, the native preparation is examined microscopically. The native preparation consists of swab material from the vagina.
If so-called clue cells can be detected under the microscope in at least 20 percent of the vaginal cells (vaginal epithelial cells), this indicates bacterial vaginosis. Clue cells are cells containing bacteria that are recognizable under the microscope as small granules.
The number of bacteria can also be assessed as part of the microscopic examination. The doctor can also see whether the colonization is a mixed infection with different types of bacteria.
The cytological examination can only provide a suspected diagnosis of "bacterial vaginosis". Further examinations are necessary for a definitive diagnosis. These include the preparation of a bacterial culture.
Creating a bacterial culture
The pathogen causing bacterial vaginosis can be clearly detected and determined with the help of a bacterial culture. It is usually performed if
- bacterial vaginosis recurs regularly (persistent recurrences) or
- to check whether other microorganisms may be responsible for the symptoms.
Differential diagnosis
A differential diagnosis should ensure that the symptoms are not caused by other diseases with similar symptoms. This is also necessary in the diagnosis of bacterial vaginosis.
Diseases with symptoms similar to those of bacterial vaginosis include
- inflammation of the vagina (vaginitis) and
- inflammation of the mucous membrane of the cervix (cervicitis).
In addition, an infection with other microorganisms such as trichomonads or mycoplasma should be ruled out.
Bacterial vaginosis is not a serious disease. However, the symptoms can be very unpleasant for the women affected. Sometimes it can also lead to complications, i.e. serious illnesses such as inflammation
- of the mucous membrane of the cervix (cervicitis),
- the lining of the uterus (endometritis),
- the fallopian tubes (salpingitis),
- the entrance to the vagina (vulvitis) or
- the Bartholin glands (Bartholinitis),
can result.
Bacterial vaginosis should therefore always be treated. Treatment is usually medicated with antibiotics.
Preparations containing lactic acid bacteria can also be used. They have a positive effect on the imbalance of the vaginal flora (vaginal flora) present in bacterial vaginosis.
Treatment with antibiotics
The administration of antibiotics is the gold standard in the medical treatment of bacterial vaginosis. The antibiotic metronidazole in particular has proven to be very successful. It is particularly effective against anaerobic bacteria. Other active substances are also available. These include clindamycin, amoxicillin and nifuratel.
Antibiotics can be administered either
- orally in the form of tablets (metronidazole) or
- intravaginally in the form of vaginal suppositories or vaginal tablets
can be administered. Topical treatment with an antibiotic vaginal cream (metronidazole, clindamycin) is also possible.
The duration of treatment depends on the severity of the disease and the ability of the vaginal flora to regenerate.
Treatment with lactic acid preparations
Local treatment with preparations containing lactic acid and vaginal suppositories containing lactic acid bacteria (lactobacilli) or ascorbic acid (vitamin C) is also possible. These preparations are available over the counter from pharmacies.
Such treatment serves to restore the natural vaginal environment. However, it is neither as quick nor as thorough as antibiotic treatment. Instead, it is mainly used after treatment with antibiotics. It is used to support the healing process that has been achieved and to prevent the recurrence of bacterial vaginosis.
Prognosis for bacterial vaginosis
If bacterial vaginosis is treated with antibiotics, the prognosis is generally good. Bacterial vaginosis usually heals within a week with the administration of antibiotics.
For example, the normal vaginal flora is restored after one week following oral administration of metronidazole. 80 percent of patients are then cured. Similarly good results are achieved with the intravaginal administration of metronidazole.
However, the relapse rate after successful treatment is quite high at 60 to 70 percent. Simultaneous treatment of the partners of affected women can prevent relapses if necessary.
Bacterial vaginosis can lead to various complications in pregnant women. Pregnant women who suffer from bacterial vaginosis have an increased risk of
- premature labor,
- premature rupture of the membranes or
- premature birth.
In addition, an infection of the embryonic membrane (amnionitis) can occur during pregnancy. This is caused by various biochemical reactions between the foetus and the uterus due to bacterial vaginosis.
Further complications can occur after delivery due to bacterial vaginosis. These include, among others
- Inflammation and delayed healing of an episiotomy,
- an abdominal wall abscess after a caesarean section and
- inflammation of the lining of the uterus (endometritis).
Bacterial vaginosis should therefore always be treated medically during pregnancy.
Bacterial vaginosis is the most common microbiological disorder of the vaginal environment in sexually mature women. In Europe, bacterial vaginosis can occur in
- in 5 percent of women who come for a check-up and
- in 30 percent of women who are treated in a clinic for sexually transmitted diseases,
are detected.
Of pregnant women in Europe, around 7 to 22 percent are affected by bacterial vaginosis. Overall, around 20 percent of all women suffer from a bacterial vaginal infection, usually bacterial vaginosis, at least once in their lifetime.
Bacterial vaginosis can only be prevented indirectly. The basic rule is: attend regular check-ups with your gynecologist! This allows existing bacterial vaginosis to be detected and treated. The gynaecologist can also intercept any emerging complications.
However, psychosocial stress is also considered a risk factor. Women with a lot of everyday stress should therefore counteract this with sport and targeted relaxation techniques. Especially if they have already suffered from bacterial vaginosis several times.
An important role in prevention: vaginal hygiene
Many women feel the need to clean their intimate area thoroughly. They use soap or shower gel and then intimate deodorant. This leaves a fresh and pleasant feeling immediately afterwards. However, this is subjective and does not last long.
Excessive vaginal hygiene, such as vaginal douching, is particularly harmful! Regular care with just water is completely sufficient and keeps the pH value of the vaginal flora at a constant level.
Chemical substances cause severe irritation in the vaginal flora, which disturbs its balance. Many body care products also have a high pH value, which throws the naturally acidic environment of the vaginal mucosa (low pH value) out of balance.
To prevent bacterial vaginosis, you should therefore only use lukewarm water for intimate hygiene. Special washing lotions that are adapted to the pH value (< 5) of the vaginal environment are also useful. They are available from pharmacies or drugstores, for example.
Special cures or lactic acid preparations can build up and acidify the vaginal flora. This serves
- the regeneration of the vaginal flora,
- rebuilding the colonization with natural lactic acid bacteria (lactobacilli) and
- stabilizing the pH value over a longer period of time.
Cleaning the anus and in particular the direction of wiping after a bowel movement can also make a significant contribution to healthy vaginal flora. By wiping in the correct direction from front to back (towards the anus and beyond), bacteria from the bowel are not inadvertently introduced into the vagina.
Keep an eye on the pH value of the vaginal flora
If you tend to have an overly acidic vaginal environment, you can also monitor this yourself using pH tests available over the counter. So-called test kits are available in pharmacies as special pH indicator papers or pH test gloves.
Bacterial vaginosis is not a sexually transmitted disease, but can be promoted by sexual intercourse. The bacteria that cause it can also be present in the male genital area. However, they do not cause any symptoms there. The man can therefore unknowingly pass them on to the woman. This means that the woman can come into contact with the bacteria again and again.
Comprehensive treatment therefore also includes treating the sexual partner of the affected woman.
Gardnerella vaginalis is also an intestinal bacterium. It is therefore often transmitted from the anal area into the vagina during sexual intercourse. Switching from anal sex to vaginal intercourse also increases the risk of introducing the bacteria into the vagina.
A condom offers safety here. A fresh condom should be used, especially when switching directly from anal sex to vaginal intercourse.
Men's intimate areas are also often colonized with bacteria such as Gardnerella.
However, the pathogenic germs do not usually cause any symptoms in men. However, the development of a mostly mild and short-lasting inflammation of the glans (balanoposthitis) is possible.