Gardnerella Vaginalis

What is Gardnerella Vaginalis?

It is a gram-variable rod, facultative anaerobic bacteria as it can appear as gram positive or gram positive. It was previously known as Haemophilus vaginalis, Coryebacterium vaginalis and finally renamed to Gardnerella vaginalis.

Gardnerella vaginalis is responsible for a disorder named Bacterial Vaginosis where the normal flora of women’s vagina is displaced by a group of other floras. Inother term, there will be an imbalance of bacterial in the vagina. Other bacteria that could cause this are Mobiluncus, Peptostreptococcus, Ureaplasma, Bacteriodes, Prevotella, Veillonella, Eubacterium and Mycoplasma hominis.The mechanism of vaginal flora imbalance is not clear and understood yet.

Bacterial vaginosis is the commonest cause for vaginitis and presents with acute symptoms for 50% of women. It is not considered a sexually transmitted disease because this can occur spontaneously; without sexually activity. Gardnerella vaginalis can be found as a normal flora of vagina in some women.

This is easily diagnosed and easily treated with antibiotics.


Gardnerella Vaginalis


  • Symptoms of Gardnerella Vaginalis
  • Pathogenesis of Gardnerella Vaginalis
  • Diagnosis and Investigation of Gardnerella Vaginalis
  • Treatment of Gardnerella Vaginalis
  • Prevention of Gardnerella Vaginalis
  • Complication of Gardnerella Vaginalis
  • Conclusion



Symptoms of Gardnerella Vaginalis

Infection of Gardnerella is usually at the vaginal, called bacterial vaginosis. Most women present with thin, greyish white discharge with fishy odour. The discharges are more prominent and copious after sexual intercourse and during menses. There can be symptoms of vaginal irritation such as itchiness, redness and edematous. Although it is rare, some women experience dyspareunia, which is pain at vagina during sexual intercourse. Not all, but it is common to have burning sensation during urination.

In some women, around 30% are asymptomatic.

For men with Gardnerella Vaginosis, they will too be asymptomatic.



Pathogenesis of Gardnerella Vaginalis

How Gardnerella vaginalis causes bacterial vaginosis is not clear as it is still in a debate. More studies and evidence suggest that the key component in this disorder is actually the biofilm produced by Gardnerella vaginalis. Some theorize that the adherence of Gardnerella vaginalis to the vaginal wall epithelium forms a net for other species of bacteria to take place and grow there.

A normal vagina flora has good amount of lactobacilli to produce hydrogen peroxide. When the amount of lactobacilli in the vagina decreases, overgrowth of vaginal anaerobs happens, this is usually the Gardnerella vaginalis. The pH of vagina increases to facilitate further growth of the organisms there. With this large amount of anaerobic bacterias, large amount of proteolytic carboxylase enzyme promotes squamous epithelial cell exfoliation and adherence of Gardnerella vaginalis. This will go into the cycle that promotes even more growth of Gardnerella vaginalis and other bacterias.



Diagnosis and Investigation of Gardnerella Vaginalis

It is important to seek medical care as many of vaginal discharge or irritations are symptoms of sexually transmitted disease. So it is advisable to seek treatment in a healthcare early, to not wait until complications develop.

There are many kits that can be found at the pharmacy or hospitals for a quick test of Gardnerella vaginalis. These tests are made in simple easy reading cards for the detection of Gardnerella vaginalis. Some are DNA probe based test for the concentration of Gardnerella vaginalis, testing for elevation of sialidase activity or test cards for proline-aminopeptidase.

A sample of discharge will be taken from the vagina for a few tests. The sample should be taken from swabs of sides of vaginal wall.


pH Test

It is a test where a pH indicator paper is used. A pH of 4.0-4.5 is normal and a pH of more than 4.5 is suggestive of Gardnerella vaginalis and Trichomoniasis.

There are also test cards that can be bought in pharmacy for quick testing. Although it is very sensitive for Bacterial vaginosis, one must remember that it is just a pH testing card. This result has to be correlated to the clinical symptoms and findings.



The obtained vaginal discharge sample will be prepared with normal saline and seen under a microsope. If more than 20% of clue cells are seen, then it is very suggestive of Bacterial vaginosis. Clue cells have granular appearance where bacteria, in coccobacilli form adhere to the squamous epithelial cells of vagina. They usually adhere at the edge of the epithelial cells giving a studded appearance.

If clue cells are seen with more white blood cells than epithelial cells, called leukorrhea, it is often associated with Chlamydia infection. Although not confirmative, it is advisable to get a STD screening done.


Whiff Test

The Whiff test is where a small portion of vaginal discharge is added with 10% potassium hydroxide. If a very strong fishy odour is present, it is very likely to be Bacterial vaginosis. This test is highly sensitive.



The culture of vaginal discharge is not indicated in the diagnosis of Gardnerella vaginalis or bacterial vaginosis. As Gardnerella vaginalis can be a normal flora in a healthy woman, so a culture will be positive in most women. Thus, culture plays no role in diagnosis of Gardnerella vaginalis.


Diagnosis Standard

The diagnostic standard in research uses Hay/Ison criteria for the evaluation of gram stain smear of vaginal discharges. But this uses more expertise, resources and very time consuming.

For that, most healthcare centres prefer to use the Amselcriteria, that is simpler and easier. This is because the test for the criteria is widely available in most hospitals and not expensive or time consuming.


Amsel criteria

Amsel criteria are often used for the diagnosis of Bacterial vaginosis. If 3 out of 4 criteria are present, then it is highly suggestive of Bacterial vaginosis.

  1. An appearance of thin vaginal discharge
  2. A vaginal pH of more than 4.5
  3. More than 20% of clue cells seen
  4. Positive Whiff test


Fast Tests

Affirm VP III

The Affirm VP III test is a DNA probe assay for detecting Gardnerella vaginalis at high concentration. It is a recommended test as it complements a physical examination of vaginal discharges’ appearance and pH testing. The best feature is that it takes less than 1 hour for the test result.


 OSOM BVBlue system

The OSOM BVBlue system is a test to detect the presence of high sialidase enzyme activity which is produced by Gardnerella vaginalis in vaginal discharge. This enzyme activity can also be produced by Mobiluncus, Bacteriodes and Prevotells. The result can be obtained between 10-20 minutes and is highly sensitive


FemExam Pip Activity Test

The FemExam Pip Activity Test card detects prolineamino peptidase activity of anaerobes, usually the Gardnerella vaginalis. It is also a very sensitive test. And the fastest test that yields result in less than 10 minutes.

There is also the FemExam pH and amines test card that detects the vaginal fluid pH where an elevation of pH is suggestive of Gardnerella vaginalis. This test is also one of the favourites as the result is ready in approximately 2-5 minutes.


 Other screenings

Although Gardnerella vaginalis or Bacterial vaginosis is not a sexually transmitted disease, it is important to remember that the commonest cause for vaginal discharge is sexually transmitted disease. It is good to have STD screening done if there is vaginal discharge and irritation.



Treatment of Gardnerella Vaginalis

Medical Treatment

Non pregnant patients

The recommended regime for Bacterial vaginosis is 7 day course of oral Metronidazole and vaginal Metronidazole gel and vaginal Clindamycin cream. The dosage for oral Metronidazole should be 500mg, to be taken twice a day. Metronidazole gel is recommended to be at 0.7% and Clindamycin cream to be 2%.

A single oral dose of high concentrated Metronidazole is not advisable.

Alternatively, if one is allergic to Metronidazole, oral Clindamycin can be taken. The dosage is recommended for 300mg twice a day for 7 days.


Pregnant patients

For pregnant patients, a lower dose of oral Metronidazole 250mg, three times a day is prescribed with vaginal Metronidazole gel and vaginal Clindamycin cream. It is important to have regular check up with a certified Obstetrician as there is a risk of preterm labour. This is to prevent preterm labour and other adverse outcomes of the pregnancy.

There is no role in screening all pregnancy with Gardnerella vaginalis. There is only indication for treatment when it is symptomatically diagnosed and investigated.


Asymptomatic patients

There is no indication for the treatment of asymptomatic patients unless she has an upcoming gynaecology procedure. Asymptomatic patients are well and has no risk of other infections.



Metronidazole is a commonly used antibiotic for anaerobic bacteria. When on a course of Metronidazole, it is important to not consume alcohol during the antibiotic course and 24 hours later to avoid disulfiram like reactions. The reactions include flushing of the skin, headache, nausea and vomiting.

Other side effects of Metronidazole are metallic taste in the mouth, transient neutropenia, prolonged INR and possibility of peripheral neuropathy. There is a chance of having an allergic reaction to Metronidazole although it is very rare. If such reactions present, please visit the nearest healthcare centre immediately.



Oral Clindamycin is usually take if one is allergic or cannot tolerate oral Metronidazole. However, oral Clindamycin has lower efficacy than oral Metronidazole. But, the vaginal Clindamycin cream is preferred more than Metronidazole gel. It is important to watchout for pseudomembranous colitis when Clindamycin is prescribed.



About 30% of women with Bacterial vaginosis will have recurrence after 3 months. While there is no solid cause for the recurrence, reinfection is possible but it is actually more likely to be due to failed eradication of the offending organism by the prescribed antibiotics.

For this group, a 2 week course of oral antibiotics is recommended with vaginal Metronidazole or Clindamycin cream.



Another important step is to stop douching or any other vaginal cleansing product as this will further displace the normal flora of the vaginal and cause more imbalance of the flora.


Sexual partners

There are no role and benefits in treating the male sexual partners as there is no association of women’s therapy response being influence by the treatment of her male sexual partner.

However, because of the high incidence of association of Bacterial vaginosis with sexually transmitted diseases, it is important to screen her male counterpart for sexually transmitted diseases.



Prevention of Gardnerella Vaginalis

Gardnerella Vaginalis infection or Bacterial vaginosis can be prevented by practicing a good vaginal hygiene. If one regularly uses a tampon during menstruation, it is advisable for a frequent change. A tampon usage of more than 6 hours predisposes to infection.

Any intrauterine device or diaphragm that is used during sexual intercourse should be cleaned before usage. The best will be using a sterile disposable device to minimise the risk of infection.

Douching is a common practice for some women. But excessive douching could displace the good and important flora in the vagina. This will cause an imbalance of flora that is predisposed to bacterial vaginosis.

A condom provides a barrier at the genitalia between men and women during sexual intercourse. Although not 100%, condom prevents the transmission of Gardnerella vaginalis from men to women or vice versa. As most men with Gardnerella vaginalisis asymptomatic, they would not know if they have them.

Finally, a monogamy sexual practice can prevent Bacterial vaginosis as it is more commonly associated with multiple sexual partners. This can also prevent sexually transmitted diseases.



Complications of Gardnerella Vaginalis

Gardnerella vaginalis infection is not a life threatening or chronic illness but it should be treated. If Bacterial vaginosis is not treated, this could lead to ascending infection. Pelvic Inflammatory Disease is not the complication, but it is closely association with sexually transmitted diseases. With that, STD could be undetected and leads to more adverse outcomes.

In pregnancy, there is a higher risk for premature labour with premature birth of a preterm baby. There could also be chorioamnionitis; the infection of amniotic fluid that could cause premature birth and predisposing the baby to sepsis. There could also be a postpartum fever experienced by mothers with Gardnerella vaginalis.




Although it is a mild condition and treatable, it is important to check for associated infections such as Gonorrhea and Chlamydia. About 60% of women with sexually transmitted disease have Bacterial vaginosis also.




We will be expanding on this important topic in future articles. While I recommend you to register to download an e-book: “Adult Prevention Guide” for better health, a FREE

Click here for PDF

We welcome your comments at the end of the article.
The Team Manager Web Diseases




VN:F [1.9.22_1171]
Rating: 6.5/10 (2 votes cast)
VN:F [1.9.22_1171]
Rating: +1 (from 1 vote)
Gardnerella Vaginalis, 6.5 out of 10 based on 2 ratings