According to a new study published on Tuesday, a terrifying yeast that kills people in hospitals can also survive very well outside of them.day. For the first time, researchers say they have discovered multidrug-resistant fungal strains Candida auris in a natural environment, in the remote wetlands of India. The findings indicate that such environments could be home to yeast, while providing evidence that global warming due to climate change has recently made the fungus dangerous to humans, as some scientists have theorized.
C. auris it was first discovered in 2009 by doctors in Japan, who isolated it from a patient’s ear infection (the first known cases date back to the mid-1990s, however). Since then, yeast has been found in more than a dozen countries, including the United States. It can cause life-threatening infections, especially in already debilitated hospitalized patients. But what makes yeast especially terrifying is that it is often resistant to multiple 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 established somewhere, it is incredibly hard to remove it from the environment. If that wasn’t enough, C. auris it cannot be easily identified by conventional tests, which can delay attention and increase the risk of death.
There have only been about 1,600 cases of yeast identified in the U.S. since 2009, but it is considered one of the most serious emerging germ threats we face today. This threat has made the understanding of its origins and possible recent introduction to people even more important. This new study, published on Tuesday at mBio, it seems to provide the first real clues to this mystery.
Researchers in India and Canada looked for isolated environmental niches in India in large part of humans that could have been habitable for yeast, based on their 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. In two of the eight places they searched, a salt marsh and a sandy beach, they found the fungus. The team found strains of C. auris which were susceptible and resistant to antifungals, and these strains bore a close genetic resemblance to the strains collected from patients in India.
In total, his work C. auris suggests that “prior to its recognition as a human pathogen, it existed as an environmental fungus,” the authors wrote.
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Compared to other species of Candida, C. auris it is known to thrive especially well at warmer temperatures. This led some researchers to question whether climate change played an important role in its emergence as a human germ. The theory argues that climate change in its natural environment led the yeast to adapt slightly and be even more tolerant of warmer temperatures, the exact type of temperatures that humans and other mammals would turn into a comfortable home once the yeast began to come into regular contact with us.
The new findings seem to add more weight to this theory. Aside from proving that these fungi can live far from people, the team found subtle differences between the samples they found. One yeast strain found in the more remote salt march was slower to grow at warmer temperatures than the varieties found on the sandy beach and another walking strain; this strain was also the only one that was found susceptible to common antifungals and less related to the strains observed in humans. Meanwhile, the other strains were all resistant to antifungals and warmer. The strains found on the beach, where people sometimes visit, may have been reintroduced into the environment by humans, which could explain why they were more related to the strains found in patients.
Researchers may have instantly collected photographs of the yeast’s evolutionary journey, before and after climate change began to alter its biology and first infect people. In an accompaniment comments written by some of the researchers who first proposed this theory — Arturo Casadevall of Johns Hopkins, Dimitrios Kontoyiannis of the Anderson Cancer Center at the University of Texas, and Vincent Robert of the Westerdijk Fungal Biodiversity Institute in the Netherlands — agreed with these conclusions.
“This iconic discovery is crucial to understanding the epidemiology, ecology and emergence of C. auris as a human pathogen, ”they wrote.
In a statement published by the American Society of Microbiology, which publishes mBio, lead author Anuradha Chowdhary, a medical mycobiologist at the University of Delhi in India, said: “This study takes the first step in understanding how this pathogen survives in the wetland, but that’s just a niche. “
The findings are still worth a study, so they alone do not show that climate change has introduced this last nightmare into our lives, which the authors acknowledge. And much remains to be decided on how and from where C. auris it came out of nature and entered our hospitals, not forgetting if there is anything that can be done to stop its spread.