Path of yeast resistance

Chan Kwok-ching, 36, has had repeated bouts of intense vaginal itching and soreness for the past two years. Each episode has been being accompanied by a burning sensation around her vaginal opening when going to the toilet as well as a thick white cottage cheese-like vaginal discharge and genital swelling.

Chan (whose name has been changed for patient confidentiality reasons) was diagnosed with recurrent vulvovaginal candidiasis, a condition typically found in menstruating women and commonly known as a vaginal yeast infection, or thrush.

'During a lifetime, 75 per cent of all women are likely to have at least one vaginal infection, and up to 45 per cent have two or more,' says Ho Pak-chung, chair professor of obstetrics and gynaecology at University of Hong Kong.

Vaginal yeast infections are typically caused by a fungus called Candida albicans. Trace amounts of the fungus are normally found in the mouth, on the skin, and inside the vagina and the intestinal tract. Yeast thrives in moist and warm environments, but the acidic environment of the vagina usually helps to prevent an overgrowth of yeast. If the vagina becomes less acidic, for example during menstruation or pregnancy, or with the use of contraceptive pills or antibiotics, an overgrowth of yeast can then cause a vaginal infection.

After Chan's initial diagnosis was confirmed by microscopic analysis and culture of a sample of cells taken from the vagina, she was treated with a single dose of an antifungal intravaginal pessary (a specially shaped lump of medication that's inserted into the vagina like a tampon) and a topical antifungal cream.

Since then, she has been plagued by monthly episodes of vaginal itching and burning. Her symptoms have been so debilitating that Chan shies away from her friends. 'The discharge is really bad; the stench is so awful I can smell it myself,' she says. 'I don't want my friends to notice. It's so embarrassing.'

For a time, she tried to wash the area as often as possible, scrubbing with soap and using sprays and douches many times a day. Unfortunately, this made things worse. 'When I told my doctor, she said that excessive washing changed the alkaline levels [in my vagina] and made the yeast grow out of control.'