Vaginal microbiome test: what it checks, and how it differs from a swab.

A vaginal microbiome test identifies the bacteria and yeasts living in the vagina by their DNA, and reports the balance between the protective species and the problem ones. It is built for symptoms that keep returning, where a standard swab has come back unhelpful, and a doctor reads it alongside your history.

What the vaginal microbiome is, and what "healthy" looks like

The vagina is not sterile and is not meant to be. It hosts a community of bacteria, dominated in most women by lactobacilli, which produce lactic acid and keep the environment mildly acidic. That acidity is the main reason other organisms struggle to take hold.

A typical healthy vaginal pH sits at about 3.8 to 4.5. A healthy community is usually dominated by one or two lactobacillus species, with only small numbers of anything else. A sizeable minority of women with no symptoms have a mixed community rather than a lactobacillus-dominant one, so the profile only means something read alongside your symptoms. Some yeast, including candida, can be present without causing any symptoms at all.

That balance is not fixed. It shifts with your cycle, with oestrogen levels across life, after antibiotics, with sex, with douching or strongly perfumed products, and during pregnancy and after menopause. Falling oestrogen after menopause thins the vaginal lining and reduces the sugars lactobacilli feed on, which is why the balance changes in those years even when nothing else has.

Symptoms that prompt testing

Most single episodes of thrush or bacterial vaginosis (BV) are managed on symptoms alone, and that works. Testing earns its place when the problem keeps coming back or does not settle. Reasons women reach for a microbiome test include:

• Thrush symptoms that return several times a year, or come back soon after each course of treatment.
• Repeated bacterial vaginosis, with thin grey discharge and an odour that is worse after sex.
• Discharge that has changed in colour, consistency or smell and stayed changed.
• Itch, burning, soreness or irritation that has no clear explanation.
• Discomfort with sex that has developed over time.
• Several standard swabs reported as "normal flora" or "mixed flora" while symptoms continue.
• Symptoms that started after antibiotics, a new contraceptive, pregnancy or the menopause transition.

Some symptoms need a doctor rather than a test. Pelvic or abdominal pain, fever, bleeding between periods or after sex, any bleeding after menopause, or symptoms in pregnancy should be reviewed promptly and in person. Where symptoms are new, or there is a new partner, a doctor may also want to exclude other infections through their own testing before or alongside a microbiome profile, because several other causes produce very similar discharge, odour and irritation. This test does not look for them.

Microbiome test, high vaginal swab or pH strip?

These three are often lumped together and they answer quite different questions.

Test	How it works	What it can and cannot tell you
High vaginal swab	A swab taken by a clinician or by you, then grown in the laboratory (culture) and examined under the microscope	More than culture alone: it includes microscopy, which is the recommended way to identify BV, and it grows candida. What it does not do is name the individual anaerobic species or report their proportions, so much of the community is summarised as "mixed flora" or "normal flora".
Vaginal microbiome test	A swab analysed by molecular methods that identify organisms from their DNA, and report how much of each is present	Names the lactobacillus species and their proportions, quantifies BV-associated organisms, identifies which candida species is present, and flags aerobic organisms. Best suited to recurrent or unresolved symptoms.
pH strip	A paper strip held against the vaginal wall or a sample, read against a colour chart	Measures acidity only. A pH above 4.5 points towards BV rather than thrush, which is a useful clue. It identifies no organism, misses mixed pictures, and is easily thrown out by blood, semen or lubricants.

Reporting formats vary by laboratory; your report shows the categories and thresholds your lab uses.

Put simply: a pH strip narrows the question, a standard swab answers it for a straightforward first episode, and a microbiome profile can add detail when symptoms keep returning and standard tests have not explained them. It complements culture and microscopy rather than replacing them.

What the result shows, and what your doctor does with it

A microbiome report is a profile rather than a single number. It typically shows whether protective lactobacilli dominate and which species they are, how many BV-associated organisms are present, whether candida is detected and which species, and whether aerobic organisms are contributing a different kind of inflammation.

Reading that profile against your symptoms is what makes it useful. A few common patterns:

• Lactobacillus-dominant, nothing else raised. Reassuring, and it steers the search for a cause elsewhere, for example towards skin conditions of the vulva or hormonal changes.
• Low lactobacilli with high BV-associated organisms. Fits the BV pattern, and usually goes with a pH above 4.5. BV is not classified as an infection passed between partners, but sexual activity contributes to it, and where BV keeps returning Australian guidance now supports treating a regular male partner as well (Australian trial, 2025), which your doctor discusses with you.
• Candida detected. Which species matters, because the less common ones behave differently from the usual one. Candida can also be present without being the cause of your symptoms.
• Aerobic organisms raised. Can be a clue to aerobic vaginitis, which is managed differently from BV. These gut and skin bacteria grow readily on culture and are often present harmlessly, and the diagnosis rests on microscopy and examination by a doctor, so a raised result is a starting point rather than an answer.
• Mixed picture. More than one imbalance at once, which is a common reason symptom-based management has not held.

What the test cannot do is tell you why the balance shifted, or put it back. It is one snapshot in time, and it does not replace an examination when there is pain, bleeding or fever. It also does not cover every cause of vaginal symptoms. Decisions about what happens next belong to the doctor who cares for you, informed by the profile rather than guessing from symptoms alone.

The KnowLuna vaginal microbiome test

The vaginal microbiome test profiles lactobacillus species, BV-associated organisms, candida species and aerobic organisms. The sample is a vaginal swab you collect yourself, following short written instructions. The default is a home kit posted to you with a prepaid return satchel; you can also collect in a private room at an accredited Australian centre, where a collector is available if you would rather have help. It takes a couple of minutes either way, and the swab goes to a NATA/RCPA-accredited laboratory.

Timing matters. Avoid collecting during your period, and avoid vaginal products, douching and sex in the 24 hours beforehand. If you have just finished antibiotics or antifungal treatment, waiting a couple of weeks shows your baseline rather than the aftermath, unless your doctor wants it sooner.

It is $249 with your own doctor's request, or $329 with a KnowLuna women's health doctor who requests it and explains the report in a 20-minute video consult. If your symptoms sit alongside cycle changes, the female hormone panel looks at the hormonal side of the picture.

Common questions

Sources and further reading

• Vodstrcil LA et al. Male-partner treatment to prevent recurrence of bacterial vaginosis. N Engl J Med 2025
• Healthdirect: bacterial vaginosis
• Healthdirect: vaginal thrush
• Better Health Channel: bacterial vaginosis
• Jean Hailes for Women's Health: vulval and vaginal conditions
• Healthdirect: vaginal discharge

General information only, not medical advice. If your symptoms are severe or sudden, see a doctor promptly. This page does not replace a consultation with a doctor who knows your history; read our medical disclaimer.