A terrifying superbug yeast that kills people in hospitals can survive just fine outside of them, too, according to a new study out Tuesday.day. For the first time, researchers say they have discovered multi-resistant strains of the fungus Candida auris in a natural environment, in the remote wetlands of India. The findings indicate that these types of environments may be the birthplace of the yeast, while also proving 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 doctors in Japan, who isolated it from a patient’s ear infection (however, the first known cases date back to the mid-1990s). Since then, the yeast has been found in more than a dozen countries, including the US. It can cause life-threatening infections, especially in already debilitated hospitalized patients. But what makes the yeast especially scary is that it is often resistant to multiple antifungal drugs at the same time, making these infections difficult to treat and treat. often deadlyThe fungus is also a survivor outside of the human body, so once it is established somewhere, it is incredibly difficult to remove it from the environment. If that wasn’t enough, C. auris cannot be easily identified through conventional tests, which can delay care and increase the risk of death.
Only about 1,600 cases of the yeast have been identified in the US since 2009, but it is considered one of the most serious threats to emerging germs we face today. That threat has made understanding its origins and its likely recent introduction to humans all the more important. This new study, published in mBio on Tuesday, the first seems to provide real clues to that mystery.
Researchers in India and Canada searched environmental niches of India that were largely isolated from humans and could have been habitable by the yeast, based on the known biology and that of related species. They collected soil and water samples from the coastal wetlands of the Andaman Islands, an archipelago not far from the mainland. They found the fungus in two of the eight locations they searched – a salt marsh and a sandy beach. The team found strains of it C. auris susceptible and resistant to antifungals, and these strains showed strong genetic similarity to strains collected from patients in India.
All in all, their job is up C. auris suggests that “before it was recognized as a human pathogen, it existed as an environmental fungus,” the authors wrote.
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Compared to other types Candida C. auris is known to thrive especially well in warmer temperatures. That has led some researchers to question whether climate change played a role in its emergence as a human germ. The theory holds that changes in the climate in their natural environment caused the yeast to adapt somewhat and become even more tolerant of warmer temperatures – just the kind of temperatures that would make humans and other mammals a comfortable home once the yeast came into regular contact. with us.
The new findings seem to add more weight to that theory. Aside from the fact that these fungi can and will live far from humans, the team found subtle differences between the samples they found. A yeast strain found in the more distant salt march grew more slowly at higher temperatures than those found on the sandy beach and a different kind of salt march; this species was also the only one found to be sensitive to common antifungals and less closely related to the strains seen in humans. Meanwhile, the other strains were all resistant to antifungals and more warm. The strains found on the beach, which people sometimes come to, could have been re-introduced into the environment by humans, which could explain why they were more closely related to the strains found in patients.
It’s possible that the researchers essentially collected snapshots of the yeast’s evolutionary journey, before and after climate change began to change their biology and they first infected humans. In an accompanying 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 – they agreed with those conclusions.
“This groundbreaking discovery is critical to understanding the epidemiology, ecology and emergence of C. auris as a human pathogen, ”they wrote.
In a pronunciation 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: is just one niche. “
The findings are still only worth one study, so they alone don’t prove that climate change introduced this latest nightmare into our lives, which the authors acknowledge. And there is still much to be resolved about how and from where C. auris have come to our hospitals from the wild, not to mention if anything can be done to stop its spread.