Tthe first tray of yellow-lidded specimens contains bits of meat—lung, perhaps, or muscle—some cerebrospinal fluid and another fluid, possibly from a brain abscess. The second contains a rainbow of colorful fungi, grown from those samples.
One growth is green and fluffy, like something you’d find in a shared house refrigerator – penicillium, perhaps. Another is a dark gray or brown, like animal fur. There are bright white fuzzballs and blackish spots. One growth leaches red into the medium in which it sits.
Fungal pathogens come here from all over Australia Adelaide laboratory, the National Mycological Reference Center, for identification. Mycologists are on the lookout for new pathogens, which are beginning to spread more as a result of climate change, and which can be deadly in the absence of effective antifungal drugs.
They work under biohazard signs, sorting samples and growing colonies on petri dishes, to cut off and put under the microscope. There is a weird, wonderful library of mycology books, a DNA sequencer and a reference collection with boxes and boxes of vials, of azole resistant Aspergillus on Zygomycetes.
Dr Sarah Kidd is the centre’s head. She was interested in Cryptococcus gattiiwhich lives in eucalyptus trees and infects koalas, before moving to Canada in 2006. And, serendipitously, there was C kittens outbreak in Vancouver while she was there. It’s been a mystery how that fungus associated with Australia turned up there, but the theories are that it has something to do with changing global temperatures, maybe some mutations.
Asked if those mutations scare her, Kidd says it’s “definitely not a good thing … but it keeps things interesting”.
The fascination with fungal pathogens has recently been fueled by the Netflix series The last of usin which Pedro Pascal, Bella Ramsey and a bunch of people were turned into zombies by a parasitic fungal infection.
“The fungus in The Last of Us, Cordycepsit definitely causes infection and kind of zombifies, if you will, insects,” says Kidd.
“But insects have a much cooler body temperature than humans… The vast majority of fungi cannot grow at 37C. So it is unlikely that we will see a human brain fungus zombification.
“Shows like The Last of Us have been really fantastic in bringing attention to mycology… Before that I think people thought of mycology as being about mushrooms, and foraging… or they knew that fungi can cause infections on skin, on toenails.
“But I think very few people, even now, really appreciate that fungi cause life-threatening infections.”
There are hundreds of fungi that can affect humans.
Almost 4 million global deaths per year are associated with fungal infections research published earlier this year in the Lancet – and it is likely that this figure is largely under-reported.
A pathogen of much greater concern than Cordyceps at the moment is Candida auris.
It affects immunocompromised patients, people in intensive care and people with cancer or HIV/AIDS.
Kidd says it can live off humans, happily coexisting, until it finds its way into the bloodstream. It is resistant to many of the existing therapies and can easily spread from person to person – not unlike superbugs, bacterial infections that have become resistant to antibiotics.
“They’re calling it the first fungal superbug,” says Kidd, “because it behaves like any of those resistant bacteria.”
Another pathogen that is beginning to emerge in Australia is Trichophyton indotineae. It’s a superficial rash, but it never goes away. People try to treat it themselves with ointment, but it does not work and its resistance grows.
“You can have entire families affected by this essentially incurable rash,” says Kidd. “We’re also starting to see them coming into Australia.”
Kidd returned to Australia from Canada to take over at the center from emeritus mycologist David Ellis, a legend in the field. Ellis is quick to point to Kidd’s impressive accomplishments, including a paper on fungal name changes that was listed in the Infectious Diseases Society of America’s top 10 papers for the year, and the book Descriptions of Medical Fungion which she was the first author.
A lack of treatments
In 2022, the World Health Organization identified four fungal pathogens as “critical”. among 19 fungi that pose the greatest threat to public health: Cryptococcus neoformans, Candida auris, Aspergillus fumigatus and Candida albicans.
The WHO highlighted the danger of having only a few antifungal medicines, the expansion of fungal diseases due to global warming and international travel and trade, and their increasing resistance to treatment.
Dr Megan Lenardon, a microbiologist at the University of New South Wales, warned just a few weeks ago that fungi have historically been overlooked in infectious disease research. She studied the study Candida species, causing thrush infections in tens of millions of people every year. While thrush itself – an overgrowth of Candida often in the mouth or genital area – is generally not dangerous, Candida can become invasive and spread through the organs and bloodstream.
“We call them ‘opportunistic invasive’ fungal pathogens because they don’t kill healthy people,” says Lenardon.
“But if they find themselves in a host that is susceptible, then they can kill.”
Lenardon warns that fungi can evolve to withstand higher temperatures, meaning they can survive in human bodies, but says the likelihood of a pandemic is “probably still relatively low”.
Still, she says, there are no vaccines at hand and few preventative treatments in the pipeline.
At the center in Adelaide, they can check for infections and take extra precautions with infected patients. They are working on specialized tests and treatments, and hope they will have enough to face what’s to come.
Kidd says we “don’t have a big problem” with Candida auris in Australia – “yet”.
