A frightening superhero yeast that kills people in hospitals may also survive outside of them, according to a new study released Tuesday.day. For the first time, researchers say they have discovered multidrug-resistant mushroom strains Candida auris in a natural environment, in the remote wetlands of India. The findings indicate that these types of environments could be the birthplace of yeast, while providing evidence that warming temperatures due to climate change have recently made the fungus dangerous to humans, as some scientists have theorized.
C. auris was first discovered in 2009 by Japanese doctors, who isolated it from a patient’s ear infection (however, the first known cases date back to the mid-1990s). Since then, yeast has been found in over a dozen countries, including the United States. It can cause life-threatening infections, especially in already weakened hospital patients. But what makes yeast more frightening is that it is often resistant to several antifungal drugs at once, making these infections difficult to treat and frequently fatal. The fungus is also a survivor outside the human body, so once it has settled somewhere, it is incredibly hard to get it out of the way. If that wasn’t enough, C. auris it cannot be easily identified by conventional tests, which can delay care and increase the risk of death.
There have been only about 1,600 cases of yeast identified in the US since 2009, but it is considered one of the most serious emerging germinal threats we face today. This threat has made it all the more important to understand its origins and, perhaps, its recent introduction into humans. This new study, published in mBio, on Tuesday, it seems to offer the first real clues for this mystery.
Researchers in India and Canada have searched in Indian niches largely isolated from humans that could have been habitable for yeast, based on its known biology and related species. They collected soil and water samples from the coastal wetlands of the Andaman Islands, an archipelago not far from the mainland. In two of the eight places they looked for – a salt marsh and a sandy beach – they found the mushroom. The team found strains of C. auris which were sensitive and resistant to antifungals, and these strains bore a close genetic resemblance to strains collected from patients in India.
In total, their work C. auris suggests that “before its recognition as a human pathogen, it existed as an environmental fungus,” the authors wrote.
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Compared to other species of Run, C. auris it is known to thrive particularly well in warmer temperatures. This has led some researchers to question whether climate change has played a role in its emergence as a human germ. The theory holds that climate change in their natural environment has led yeast to adapt easily and become more tolerant of warmer temperatures – the exact type of temperatures that would make humans and other mammals a comfortable home once the yeast began to enter. regularly in contact with us.
The new findings seem to add more weight to this theory. In addition to showing that these mushrooms can and do live far from humans, the team found subtle differences between the samples found. A yeast stalk found in the more distant salt march was slower to grow at warmer temperatures than the stems found on the sandy beach and another stalk of the salt march; this strain was also the only one found to be susceptible to common antifungals and less closely related to the strains observed in humans. Meanwhile, the other strains were all resistant to antifungals and more heat-loving. The strains found on the beach, where people sometimes visit, could have been reintroduced into the environment by humans, which could explain why they were more closely related to the strains found in patients.
Researchers may have collected essentially snapshots of the yeast’s evolutionary journey, before and after climate change began to change its biology and first infected humans. In a companion comment written by some of the researchers who first proposed this theory – Arturo Casadevall of Johns Hopkins, Dimitrios Kontoyiannis of the University of Texas MD Anderson Cancer Center and Vincent Robert of the Westerdijk Fungal Biodiversity Institute in the Netherlands – agreed with these conclusions .
“This reference finding is crucial to understanding epidemiology, ecology and emergence C. auris as a human pathogen, “they wrote.
One statement published by the American Society for Microbiology, which publishes mBio, lead author Anuradha Chowdhary, a medical mycobiologist at the University of Delhi in India, said: thing is just a niche. ”
The findings are still worth a single study, so they alone do not show that climate change has introduced this latest nightmare into our lives, which the authors acknowledge. And there is still much to be done about how and where C. auris it came out of the wild and into our hospitals, not to mention if anything can be done to stop it from spreading.