Millions of women in the UK are suffering the agony of repeated attacks of vaginal thrush and many of them cannot be cured, experts warn.
In one study, researchers examined swabs taken from patients who had suffered at least four episodes of fungal infection in 12 months, classified as recurrent.
Of those, 15 percent were found to be resistant to the most potent first-line treatment, fluconozole, and other potent antifungals.
It means that in some of these cases, the infection will be almost impossible to treat, meaning women may have to rely on medication to keep symptoms at bay for life.
Overuse of common antifungals could be to blame, said the scientists behind the research, which was published in the journal Sexually Transmitted Infections.
Vaginal candidiasis is common and three out of four women of reproductive age are likely to be affected.
White discharge, pain, and itching around the vagina are telltale signs of yeast infection.
Candidiasis, also known as candidiasis, is caused by a type of yeast called Candida.
Normally, this lives harmlessly in the body, but sometimes it can grow out of control and damage healthy tissues.
The infection can affect the mouth, throat, penis and vagina and causes itching, irritation and pain and sometimes discharge in women.
In recent years there has been concern among skin specialists that some cases are becoming more difficult to address, with patients having to use treatments regularly for many months rather than weeks.
Just as harmful bacteria have become immune to common antibiotics, a similar pattern is emerging with fungal infections.
To understand the magnitude of the problem, researchers examined laboratory results taken from thousands of UK women with recurrent yeast infections between 2018 and 2021.
Most were found to be caused by Candida albicans, the fungus usually responsible for vaginal yeast infection.
But there was a year-over-year increase in other Candida species, of which the most common was Nakaseomyces glabrata, a species resistant to standard treatments.
In 2018, around one in 20 cases were due to these “other” species, and this will increase to one in ten in 2020.
Overall, three percent of cases were found to be resistant to one of the most standard medications, including fluconozole, a figure that rose to almost 10 percent in 2020.
Fluconazole is used to treat vaginal candidiasis, but resistance to the antifungal has quadrupled in the last three years.
“The increase in non-albicans species is of clinical concern, as some have reduced intrinsic susceptibility to fluconazole,” the researchers noted.
“Successful treatment of fluconazole-resistant Candida albicans and non-albicans species can be very challenging, and this often requires multiple courses of antifungals.
“Many of these yeasts also had reduced sensitivity to (second-line drugs) itraconazole and voriconazole, further limiting treatment options,” the researchers added.
Since 2013, UK primary care guidelines recommend that a clinical diagnosis of acute vaginal thrush be made based on typical signs and symptoms, such as itching and discharge.
Doctors can also assess vaginal pH for signs of candidiasis and follow up with a treatment such as a single dose of oral fluconazole or clotrimazole pessary, which is a tablet inserted vaginally, the researchers say.
But there is evidence that both doctors and patients overdiagnose vaginal candidiasis, and researchers suggest this may lead to unnecessary use of antifungal treatments, which may have led to the development of resistance.
The researchers said: ‘The exact reasons for this increase (in fluconazole resistance) are still unclear, but it is due to the introduction of restricted access to fungal cultures for diagnosis (of vulvovaginal candidiasis) by those They work in primary care.
‘Instead, a clinical diagnosis followed by empirical treatment is recommended. “Consequently, we believe it is necessary to review this policy of encouraging empirical treatment of vaginitis based on non-specific symptoms and signs.”