The facts about thrush
How do I know I've got thrush?
Thrush causes one or more of the following: genital itch, burning, soreness, discomfort with sex, discharge and sometimes a characteristic odour.
However, thrush can only be accurately diagnosed by culturing the yeast Candida albicans. This is done by taking a swab from the vagina; it is not necessary to use an instrument to open the vagina. The swab is placed in a special tube and sent to the laboratory. Although genital itch in women in the reproductive years is most commonly caused by this yeast, this symptom has many other causes. This is why laboratory investigation is essential whenever itch returns or does not respond to treatment as expected. Anti-thrush medication must not be used for a week or more before the swab is taken, because this medication will interfere with the result.
Do all species of Candida cause thrush?
No. Candida albicans is by far the most important cause of thrush. Other species of yeast are often found when vaginal swabs are tested as above. These non-albicans yeasts (Candida glabrata is the commonest) seldom, if ever, produce clinical disease and therefore should not require treatment.
When is anti-thrush treatment appropriate?
Anti-fungal creams or pessaries inserted into the vagina are highly effective treatment for clinical (symptomatic) infection with Candida albicans. One applicator of anti-fungal cream should be inserted high into the vagina every night for a week. Note that the treatment should be continued during menstruation. Anti-fungal vaginal preparations are generally not suitable for long term treatment. Vaginal nystatin may be used for recurrent thrush in pregnancy, however. Oral anti-fungal tablets are best used only in the more difficult cases and on medical advice.
It is both unnecessary and inadvisable to apply anti-fungal cream to the vulva because, even though vulvar itch is the commonest symptom, the infection is within the vagina. The vulva merely gets ‘burnt’ by the infected vaginal secretions. Under these circumstances, anti-fungal creams can cause further vulvar irritation if applied to the exterior.
Can Candida albicans develop resistance to anti-fungal drugs?Minimal resistance of Candida albicans to anti-fungal agents has been reported to date. Non-albicans yeasts (see above) are often resistant to the commonly used anti-fungals and keep showing up on swabs as a result, but, as stated above, should not require treatment.
Do male partners need treatment too?
No. Male genital skin does not have the glycogen (sugar) containing cells like those of the vagina that make women thrush prone. Rare, possible exceptions are men with infected foreskins (balanitis) or groin rashes (intertrigo).
Why don’t young girls and older women get thrush?
The vagina needs to be stimulated by the ovarian hormone oestrogen to make it thrush prone. Thus, the infection is not a problem before puberty or after the menopause unless oestrogen therapy is being used. In diabetics, thrush can occur at any age.
How do I prevent thrush?
Many means of prevention of thrush have been recommended. They include diet, clothing and hygiene. Their effectiveness has never been scientifically confirmed.
Much has been written and said about the relationship between thrush and contraception. Contrary to common belief, the oral contraceptive pill does not cause thrush. As the infection is not sexually transmitted, condoms make no difference. However, thrush has a much lower incidence with the use of what are known as the long acting injectable progestogens. Depo Ralovera (also known as Depo Provera) and Implanon are the ones available in Australia. These hormonal contraceptives act by preventing ovulation without adding oestrogen (as in the pill). It is the lower oestrogen levels in users of these methods that appear to lower their susceptibility to thrush. Postmenopausal women on HRT, who have been shown to be getting thrush, may need to lower the oestrogen dosage.
Antibiotics promote yeast growth, so restriction of antibiotic usage, where possible, will lower the incidence of the infection. Some forms of diabetes can be prevented by dietary means and there is a much higher incidence of thrush in diabetics.
Finally, breastfeeding has a similar effect to the injectable progestogen contraceptives on oestrogen levels and is protective against thrush.
When should I see a doctor?
If you feel you need more than one course of anti-fungal in, say, a year, then you need further investigation.
Author: Graeme Dennerstein MB, BS, FRCOG, FRANZCOG. March 2013.