Gardnerella Vaginalis: Symptoms, Risks, and Treatment

Medically Reviewed By: Dr Jana Lim, Board-Accredited Family Physician

Board-Accredited Family Physician | MBChB, MMed (FM)

MBChB, MMed (FM) | Last updated: 12 Oct 2026

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What Is Gardnerella Vaginalis?

Gardnerella vaginalis is a type of bacteria that lives naturally in the vagina. It is harmless in small numbers, but an overgrowth can trigger a condition called bacterial vaginosis (BV).

This overgrowth usually follows a drop in helpful lactobacilli, the bacteria that keep the vagina acidic and protected. With fewer lactobacilli, the vagina becomes less acidic, and Gardnerella and other bacteria can multiply more easily.

BV is seen more often in sexually active women, although it is not strictly a sexually transmitted infection (STI). Repeated episodes that go untreated can sometimes lead to complications affecting pregnancy or reproductive health.

What Can Cause Gardnerella Vaginalis Overgrowth?

An increase in Gardnerella vaginalis usually occurs when the natural bacterial harmony of the vagina is disrupted. A variety of internal and external influences can cause this shift, including:

• Engaging in sexual activity without protection or with new partners
• Taking antibiotics that disturb normal bacterial flora
• Hormonal changes during menstruation, pregnancy, or menopause
• Frequent vaginal douching or use of scented hygiene products

Although it is not categorised as a classic STI, the condition appears more frequently in individuals whose vaginal microbiota changes due to sexual exposure. It can also arise in those who are not currently sexually active, as the underlying cause relates to microbial imbalance rather than transmission alone.

What Are Symptoms of Gardnerella Vaginalis?

When Gardnerella vaginalis becomes dominant in the vaginal flora, bacterial vaginosis may develop, producing characteristic symptoms that are often distinct but not always noticeable.

Common symptoms include:

• A noticeable fish-like odour, especially after intercourse
• A thin, greyish or whitish discharge
• Vaginal irritation, itching, or mild burning sensations
• A stinging feeling when urinating

In some women, BV may cause no obvious symptoms, especially in the early stages. Routine check-ups or screening are useful when changes in discharge or odour are noticed, even if discomfort is minimal.

What Are the Risks of Untreated Gardnerella Vaginalis?

Untreated bacterial vaginosis related to Gardnerella vaginalis can lead to several reproductive and systemic complications.

Possible risks include:

• Increased susceptibility to STIs — An imbalanced vaginal environment can weaken natural defences, allowing viruses and other bacteria to infect more easily.
• Pregnancy-related problems — BV during pregnancy has been associated with preterm birth and low birth weight.
• Pelvic inflammatory disease (PID) — Bacteria may travel upwards into the uterus or fallopian tubes, potentially leading to chronic inflammation and infertility.
• Post-surgical infections — Medical procedures such as IUD insertion or gynaecological surgery can carry greater risk if the vaginal flora is unbalanced.

How Is Gardnerella Vaginalis Diagnosed?

Diagnosing Gardnerella vaginalis focuses on identifying bacterial vaginosis and confirming that the bacteria are present in large numbers. A vaginal swab is typically taken to assess bacterial composition.

Laboratory tests commonly include:

• Microscopic evaluation — Detects "clue cells," vaginal epithelial cells coated with bacteria.
• pH measurement — A reading above 4.5 often indicates reduced vaginal acidity.
• Whiff test — Adding a potassium hydroxide solution may produce a distinctive fishy odour, supporting a BV diagnosis.
• Nucleic acid amplification tests (NAATs) — Sensitive molecular tests that identify bacterial DNA and confirm the specific organisms involved.

How Is Gardnerella Vaginalis Infection Treated?

Treating Gardnerella vaginalis aims to re-establish the healthy bacterial balance of the vagina and eliminate overgrowth.

Antibiotic therapy remains the standard approach, most often using metronidazole or clindamycin, which can be taken orally or applied intravaginally depending on clinical assessment.

For recurrent or persistent cases, probiotics may help support the regrowth of beneficial bacteria and reduce recurrence rates. Reviewing hygiene habits, sexual practices, and medication use can also help identify triggers and lower future risk. Follow-up visits are also recommended if symptoms persist or reappear after treatment completion.

How Can Gardnerella Vaginalis Infection Be Prevented?

Preserving a balanced vaginal microbiome is key to preventing Gardnerella overgrowth. Practical steps include:

• Avoid vaginal douching, as it disrupts natural bacterial defences.
• Use condoms consistently during sexual activity to maintain bacterial balance.
• Complete any antibiotic course exactly as prescribed to minimise disruption of healthy flora.
• Choose breathable cotton undergarments and avoid prolonged dampness in the genital area.

Simple lifestyle measures combined with timely screening can help maintain vaginal health and reduce the likelihood of recurrence.

Cost of Gardnerella Vaginalis Testing & Treatment

Testing and treatment for bacterial vaginosis linked to Gardnerella vaginalis are available at Singapore Women's Clinic, with the prices as follows:

Test / Treatment	Price*
Consultation	From $49.05
DNA Probe/Multiplex Real Time PCR for Vaginitis – Swab Test Gardnerella vaginalis, Candida albicans and Trichomonas vaginalis Gardnerella vaginalis, Candida albicans and Trichomonas vaginalis	$147.15
STD Screening Packages
Basic Female Genital Screen (5 tests) – Swab Test Chlamydia PCR, Gonorrhoea PCR, Candida, Gardnerella Vaginosis, Trichomonas Chlamydia PCR, Gonorrhoea PCR, Candida, Gardnerella Vaginosis, Trichomonas	$268
Enhanced Female Genital Screen (9 tests) – Swab Test Chlamydia, Gonorrhoea, Mycoplasma genitalium, Mycoplasma hominis, Trichomonas, Ureaplasma parvum, Ureaplasma urealyticum, Candida, Gardnerella Vaginosis Chlamydia, Gonorrhoea, Mycoplasma genitalium, Mycoplasma hominis, Trichomonas, Ureaplasma parvum, Ureaplasma urealyticum, Candida, Gardnerella Vaginosis	$348
Complete Female STD Screen (15 tests) – Blood + Swab Test HIV, Syphilis, Hepatitis B, Hepatitis C, Herpes Simplex Virus 1 and 2, Chlamydia, Gonorrhoea, Mycoplasma genitalium, Mycoplasma hominis, Trichomonas, Ureaplasma parvum, Ureaplasma urealyticum, Candida, Gardnerella Vaginosis HIV, Syphilis, Hepatitis B, Hepatitis C, Herpes Simplex Virus 1 and 2, Chlamydia, Gonorrhoea, Mycoplasma genitalium, Mycoplasma hominis, Trichomonas, Ureaplasma parvum, Ureaplasma urealyticum, Candida, Gardnerella Vaginosis	$478
Treatment
Oral Antibiotics	From $0.87 per tab
Intravaginal Antibiotics	$59.95 per box

*All prices are NETT and inclusive of GST.

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