Vulvovaginal candidiasis

What is vulvovaginal candidiasis?

Vulvovaginal candidiasis refers to vaginal and vulval symptoms caused by a yeast, most often Candida albicans. It affects 75% of women on at least one occasion over a lifetime.

Overgrowth of vaginal candida may result in:

• White curd-like vaginal discharge
• Burning sensation in the vagina and vulva
• An itchy rash on the vulva and surrounding skin.

Other names used for vulvovaginal candidiasis are 'vaginal thrush’, ‘monilia’, and 'vulvovaginal candidosis'.

What causes vaginal discharge?

Vaginal discharge is a normal process which keeps the mucosal lining of the vagina moist. The amount of vaginal discharge varies according to the menstrual cycle and arousal and is clear and stringy in the first half of the cycle and whitish and sticky after ovulation. It may dry on underclothes leaving a faint yellowish mark. This type of discharge does not require any medication even when quite profuse, as is often the case in pregnancy. It tends to reduce in amount after menopause.

The most common microorganisms associated with abnormal vaginal discharge are:

• Candida albicans and non-albicans candida species
• Trichomoniasis (due to a small parasite, Trichomonas vaginalis); this causes a fishy or offensive odour and a yellow, green or frothy discharge
• Bacterial vaginosis (due to an imbalance of normal bacteria that live in the vagina); this causes a thin, white/grey discharge and offensive odour.

Excessive vaginal discharge may also be due to injury, foreign bodies, sexually transmitted infections, and inflammatory vaginitis.

What is the cause of vulvovaginal candidiasis?

Vulvovaginal candidiasis is due to an overgrowth of yeasts within the vagina, most often C. albicans. About 20% of non-pregnant women aged 15–55 harbour C. albicans in the vagina without any symptoms.

Oestrogen causes the lining of the vagina to mature and to contain glycogen, a substrate on which C. albicans thrives. Symptoms often occur in the second half of the menstrual cycle when there is also more progesterone. Lack of oestrogen makes vulvovaginal candidiasis less common in younger and older postmenopausal women.

Nonalbicans candida species, particularly C. glabrata, are observed in 10–20% of women with recurrent vulvovaginal candidiasis.

Who gets vulvovaginal candidiasis?

Vulvovaginal candidiasis is most commonly observed in women in the reproductive age group. It is quite uncommon in prepubertal and postmenopausal females. It may be associated with the following factors:

• Flares just before and during menstruation
• Pregnancy
• Higher dose combined oral contraceptive pill
• Oestrogen-based hormone replacement therapy after the menopause, including vaginal oestrogen cream
• A course of broad-spectrum antibiotics such as tetracycline or amoxicillin
• Diabetes mellitus
• Obesity
• Iron deficiency anaemia
• Immunodeficiency such as HIV infection
• An underlying skin condition, such as vulval psoriasis, lichen planus or lichen sclerosus
• Other illness.

What are the symptoms?

Vulvovaginal candidiasis is characterised by:

• Itching, soreness and burning discomfort in the vagina and vulva
• Stinging when passing urine (dysuria)
• Vulval oedema, fissures and excoriations
• Dense white curd or cottage cheese-like vaginal discharge
• Bright red rash affecting inner and outer parts of the vulva, sometimes spreading widely in the groin to include pubic areas, groin and thighs.

The rash is thought to be a secondary irritant dermatitis, rather than a primary skin infection.

Symptoms may last just a few hours or persist for days, weeks, or rarely, months, and can be aggravated by sexual intercourse.

• Recurrent vulvovaginal candidiasis is usually defined as four or more episodes within one year (cyclic vulvovaginitis).
• Chronic, persistent vulvovaginal candidiasis may lead to lichen simplex — thickened, intensely itchy labia majora (the hair-bearing outer lips of the vulva).

See images of vulvovaginal candidiasis.

How is the diagnosis of vulvovaginal candidiasis made?

The doctor diagnoses the condition by inspecting the affected area and recognising a typical clinical appearance.

• The pH of the vagina tends to be in the normal range (3.8–4.5, ie, acidic), but candida can occur over a wide range of pH.
• The diagnosis is often confirmed by microscopy of a wet mount, vaginal swab or vaginal smear, best taken four weeks after earlier treatment.
• In recurrent cases, a swab for culture should be collected after treatment to see whether C albicans is still present.

Swab results can be misleading and should be repeated if symptoms suggestive of candida infection recur.

• C. albicans can be present without causing symptoms (a false-positive result).
• The yeast can only be cultured when a certain amount is present (a false-negative result).
• Swabs from outside the vagina can be negative, even when the yeast is present inside the vagina, and there is a typical rash on the vulva.
• The patient's symptoms may be due to an underlying skin condition such as lichen sclerosus.

Other tests include culture in Sabouraud chloramphenicol agar or chromagar, the germ tube test, DNA probe testing by polymerase chain reaction (PCR), and spectrometry to identify the specific species of candida.

Researchers debate whether nonalbicans candida species cause disease or not. If nonalbicans candida is detected, the laboratory can perform sensitivity testing using disc diffusion methods to guide treatment. Sensitivity to fluconazole predicts sensitivity to other oral and topical azoles. C. glabrata is often resistant to standard doses of oral and topical azoles.

What is the treatment of vulvovaginal candidiasis?

Appropriate treatment for C. albicans infection can be obtained without a prescription from a chemist. If the treatment is ineffective or symptoms recur, see your doctor for examination and advice in case symptoms are due to another cause or a different treatment is required.

There are a variety of effective treatments for candidiasis.

• Topical antifungal pessaries, vaginal tablets or cream containing clotrimazole or miconazole — one to three days of treatment clears symptoms in up to 90% of women with mild symptoms. Note that oil-based products may weaken latex rubber in condoms and diaphragms.
• Newer formulations include butoconazole and terconazole creams.
• Oral antifungal medicines containing fluconazole or less frequently, itraconazole, may be used if C albicans infection is severe or recurrent. Note that these drugs may interact with other medicines, particularly statins, causing adverse events.

Vulvovaginal candidiasis often occurs during pregnancy and can be treated with topical azoles. Oral azoles are best avoided in pregnancy.

Not all genital complaints are due to candida, so if treatment is unsuccessful, it may because of another reason for the symptoms.

Recurrent candidiasis

In about 5–10% of women, C albicans infection persists despite adequate conventional therapy. In some women, this may be a sign of iron deficiency, diabetes mellitus or an immune problem, and appropriate tests should be done. The subspecies and sensitivity of the yeast should be determined if treatment-resistance arises.

Recurrent symptoms due to vulvovaginal candidiasis are due to persistent infection, rather than re-infection. Treatment aims to avoid the overgrowth of candida that leads to symptoms, rather than complete eradication.

The following measures can be helpful.

• Loose-fitting clothing — avoid occlusive nylon pantyhose.
• Soak in a salt bath. Avoid soap — use a non-soap cleanser or aqueous cream for washing.
• Apply hydrocortisone cream intermittently, to reduce itching and to treat secondary dermatitis of the vulva.
• Treat with an antifungal cream before each menstrual period and before antibiotic therapy to prevent relapse.
• A prolonged course of a topical antifungal agent is occasionally warranted (but these may themselves cause dermatitis or result in the proliferation of non-albicans candida).
• Oral antifungal medication (usually fluconazole), which is taken regularly and intermittently (eg, 150–200 mg once a week for six months). The dose and frequency depend on the severity of symptoms. Relapse occurs in 50% of women with recurrent vulvovaginal candidiasis when they are discontinued, in which case re-treatment may be appropriate. Some women require long-term therapy.
• Oral azoles may require a prescription. In New Zealand, single-dose fluconazole is available over the counter at pharmacies. The manufacturers recommend that fluconazole is avoided in pregnancy.
• Boric acid (boron) 600 mg as a vaginal suppository at night for two weeks reduces the presence of albicans and non-albicans candida in 70% of treated women. It can be irritating and is toxic, so should be stored safely away from children and animals. Twice-weekly use may prevent recurrent yeast infections. Boric acid should not be used during pregnancy.

The following measures have not been shown to help.

• Treatment of sexual partner — males may get a brief skin reaction on the penis, which clears quickly with antifungal creams. Treating the male doesn't reduce the number of episodes of candidiasis in their female partner.
• Special low-sugar, low-yeast or high-yoghurt diets
• Putting yoghurt into the vagina
• Probiotics (oral or intravaginal lactobacillus species)
• Natural remedies and supplements (except boric acid)