The indiscriminate use of over-the-counter treatments and the misuse of prescriptions by women afflicted with yeast infections may make the condition more difficult to treat in the future, says a group of University of Toronto researchers.
Laboratory experiments by U of T at Mississauga botany professors Linda Kohn and James Anderson and grad student Leah Cowen show that cells repeatedly exposed to azole drugs - the most commonly used and prescribed anti-fungal treatments for yeast infections - develop resistance to that drug.
"It was assumed that when you finish a course of drug therapy, you have killed off all of the fungus or infection. If there are any drug resistant organisms left, it was thought that they'd be weaker, wouldn't grow as well and just die out," explains Kohn. However, her work with Anderson and Cowen runs counter to that assumption.
"Our research has shown that drug resistant microbes not only compete well, they are able to evolve and adapt to overcome problems or weaknesses relatively easily," adds Anderson. "In some populations, the drug resistant microbes even grew faster and started to overtake the microbes that showed no drug resistance." And that is worrisome, say the researchers, especially if a person gets sick again. The infection may not be more virulent, but it could be resistant to the original drug, and that means taking the same drug therapy may not help.
About 75 per cent of all women between 18 and 35 will experience at least one yeast infection caused by Candida albicans, one of the most common types of yeast fungus.
The research was funded by Pfizer Canada Ltd. and the Natural Sciences and Engineering Research Council of Canada.
CONTACT: Professor Linda Kohn, department of botany, (905) 828-3997,
kohn@credit.erin.utoronto.ca,
Professor James Anderson, department of botany, (905) 828-5362,
janderso@credit.erin.utoronto.ca,
or Janet Wong, U of T public affairs, (416) 978-6974,
jf.wong@utoronto.ca.
Journal
Journal of Bacteriology