PCR detection of Gardnerella vaginalis

Have you noticed thin, greyish-white discharge with an unpleasant, “fishy” smell, particularly after sexual intercourse? This is a typical sign of bacterial vaginosis, the most common cause of unusual discharge in women. PCR detection of Gardnerella vaginalis from a swab or urine shows whether the bacterium playing the main role in this imbalance is present.

Who the test is for

• women with thin, greyish-white discharge and an unpleasant smell, particularly after sexual intercourse or menstruation;
• women with recurrent bacterial vaginosis;
• when symptoms persist after treatment;
• pregnant women with increased discharge or an unpleasant smell, on a gynaecologist’s recommendation;
• as part of broader testing to identify the cause of discharge, alongside Candida and Trichomonas.

What the test reveals

In a healthy vagina, lactobacilli predominate: “good” bacteria maintaining an acidic environment. In bacterial vaginosis, their numbers fall and other bacteria multiply, the most important being Gardnerella vaginalis. PCR finds its genetic trace in the sample.

Gardnerella is also present in smaller quantities in many healthy women. A positive result alone is therefore not a diagnosis of bacterial vaginosis: a doctor diagnoses it based on symptoms, examination and discharge appearance. Bacterial vaginosis is not a conventional sexually transmitted disease, but is more common with new partners and is associated with premature birth during pregnancy.

The procedure and preparation

Women provide a vaginal swab or first-catch urine; they can also collect a vaginal swab themselves at home using a self-sampling kit obtained from a branch, then return the sample to the branch. Men provide first-catch urine or a genital swab.

For urine, the first morning urination is best, or urination after not urinating for at least two hours, collecting only the first portion. Do not collect a swab during menstruation, and do not use vaginal creams, pessaries, vaginal probiotics or douches for two to three days beforehand. If possible, provide the sample before starting treatment. Bring the urine sample as soon as possible, preferably within 2 hours.

What your result means

• Positive with symptoms: together with examination, supports a diagnosis of bacterial vaginosis. A doctor prescribes an antibiotic as tablets, vaginal pessaries or gel.
• Positive without symptoms: is often part of the usual flora and generally is not treated. A doctor assesses exceptions.
• Negative: Gardnerella vaginalis was not detected in that sample. This does not rule out bacterial vaginosis, particularly if the sample was urine: a doctor assesses it through examination and appropriate vaginal tests. If symptoms persist, the cause may be Candida, Trichomonas or another inflammation.

A doctor interprets the result alongside examination and other results. Bacterial vaginosis returns within a year in more than half of women. With frequent recurrences in a stable relationship, a doctor may suggest simultaneous partner treatment according to newer recommendations.

How to arrange testing

The test is available without a referral or appointment. A nurse takes the swab, while urine or a swab collected at home can be handed in at any of our branches (list on the page Contact). You can also be tested anonymously, without disclosing personal details. Prices for all tests and panels are listed in the price list. Gardnerella, together with Candida, Trichomonas, chlamydia, gonorrhoea, mycoplasmas, ureaplasmas and HPV, is included in the STD10 full panel, and other options are described on the page STI testing.

Frequently asked questions

Is Gardnerella a sexually transmitted disease?

Not in the conventional sense. Bacterial vaginosis develops because of an imbalance of vaginal bacteria, although it is more common in women with new or multiple partners.

How does bacterial vaginosis differ from a fungal infection?

In vaginosis, discharge is thin, greyish and unpleasant-smelling, usually without itching. In a fungal infection, discharge is thick and white without a strong smell, and itching and burning predominate.

Should men be tested for Gardnerella?

Men with Gardnerella most often have no symptoms. Testing may be useful for inflammation of the glans or when a partner’s bacterial vaginosis frequently returns; a doctor can advise you about this.

What can I do to prevent vaginosis recurring?

Avoid vaginal douching and scented intimate products, and use a condom with new partners. For frequent recurrences, a doctor may suggest extended treatment.