A fungal superbug called Candida auris is spreading through hospitals and nursing homes at an “alarming rate,” with the United States Centers for Disease Control and Prevention (CDC) recently calling it an urgent antimicrobial resistance threat.
Last week, the CDC warned about the increasing threat of Candida auris, also called C. auris, as it not only is highly resistant to multiple antifungal drugs but also can withstand common hospital disinfectants.
“CDC has deemed C. auris as an urgent AR [antimicrobial resistance] threat, because it is often resistant to multiple antifungal drugs, spreads easily in healthcare facilities, and can cause severe infections with high death rates,” the statement read.
This worry extends beyond the U.S.
Since the pathogen was first discovered in Japan in 2009, it has spread worldwide, triggering prolonged and challenging outbreaks in hospitals and long-term care homes, including in Canada.
In January, Public Health Ontario officially labelled the fungal pathogen a “disease of public health significance.” This means it’s now considered a public health risk and needs to be closely monitored, with measures in place to prevent and control its spread.
“Candida auris is a yeast species,” said Jason Tetro, a microbiologist based in Edmonton and a specialist in emerging pathogens.
“It’s a normal colonizer of the skin, and it can essentially hang out and do absolutely no harm to you. But if it happens to get into the mucous membrane areas or happens to get into your bloodstream, it can cause an infection and that can lead to significant problems.”
The mortality rate for those infected can be as high as 50 to 60 per cent, he said. Tetro emphasized that the pathogen is especially dangerous for people with compromised immune systems.
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Even when patients survive, they can remain colonized with the fungus for years after treatment and potentially pass it along unsuspectingly.
The fungus can also spread from person to person and survive on surfaces like bedrails, doorknobs and medical equipment, potentially lasting for weeks. And many cleaners don’t kill it.
“Most yeasts have an external shell that protects them against a lot of different types of these cleaners,” Tetro said. “So unless you’re using a hydrogen peroxide or a bleach, you’re really not going to get anywhere.”
A study published March 17 in the American Journal of Infection Control examined the growth of C. auris in hospital settings in Florida. It found the fungus has “rapidly increased” from 2019 to 2023.
The number of clinical cultures increased each year, from five in 2019 to 29 in 2020, 71 in 2021, 107 in 2022 and 115 in 2023. All of the cultures sampled were resistant to a common antifungal treatment called fluconazole, the study said.
In Canada, 51 cases of C. auris were identified across six provinces from the year it was first discovered in 2012 to October 2023, according to the Public Health Agency of Canada (PHAC).
The U.S. has seen a much more alarming increase in cases.
C. auris was first detected in the U.S. in 2016, though case numbers remained low until the “dramatic increase in 2021,” the CDC said, adding that cases keep rising every year. In 2016, there were 51 reported cases of the fungus, but by 2023, that number had surged to 4,515 new cases.
Although the number of cases in Canada is relatively lower than in the U.S., Tetro said, because it is resistant to treatments, it’s still a big concern.
But he noted that it is not pan-drug-resistant yet, meaning the fungus hasn’t become resistant to all or nearly all available antibiotics or antifungal drugs.
“Some of the more standard antifungals that you’ll see that you can get over the counter or through prescriptions, unfortunately, don’t work. But there are some drugs that will work. It’s just that we don’t normally give that to the public,” he said.
Another concern Tetro has is how easily it can spread from person to person.
In many cases, people with C. auris may not show obvious symptoms, especially those who are colonized (carrying the fungus but not actively infected), making it harder to detect. However, for some people, symptoms can include a urinary tract infection, fever and chills, or a bloodstream infection.
Although C. auris poses a serious threat to global human health, Tetro believes that with proper surveillance, detection and strict infection control measures, its spread can be managed.
“We really didn’t know how to deal with Candida auris in the past. We’re starting to figure it out,” he said.
“We’re learning how to treat it properly…. When you have a pathogen that has outwitted our normal medical procedures, you have to come up with a better medical procedure. That’s the only way you’re going to be able to beat this. And we’re getting there.”
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