A deadly hospital superbug has been discovered on a remote island beach, marking the first time researchers have seen this multi-resistant organism in the “wild”.
The findings, published Tuesday (March 16) in the journal mBio, could provide clues to the origin of this superbug, Candida auris, which mysteriously showed up in hospitals around the world about a decade ago.
“It’s a medical mystery, where does it come from,” said Dr. Arturo Casadevall, chair of the Department of Molecular Microbiology and Immunology at Johns Hopkins Bloomberg School of Public Health in Baltimore, who wrote an editorial accompanying the study. The new findings are “a very important piece of the puzzle,” Casadevall told Live Science.
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C. auris is a fungus first discovered in 2009 in a patient in Japan. It seemed too soon spread all over the world, which appear on three different continents around the same time. The microbe can cause serious bloodstream infections, especially in patients who require catheters, feeding tubes or breathing tubes, according to the Centers for Disease Control and Prevention (CDC)The infections can be difficult to treat because the microbe is often resistant to multiple antifungals; and it can also linger on surrounding surfaces. “When it gets to a hospital, it’s a nightmare” for infection control, Casadevall said. In 2019 the CDC stated C. auris a “urgent threat” to public health
Although related species have been found in plant and aquatic environments, C. auris has not been found in natural environments. Casadevall and colleagues have previously hypothesized that elevated temperatures are the result of climate change may have caused C. auris to adapt to higher temperatures in the wild, and so the fungus could make the leap to humans, whose normal body temperature is usually too hot for most fungi to survive.
Inspired by this hypothesis, lead author Anuradha Chowdhary, a medical mycologist at the University of Delhi, India, and colleagues analyzed soil and water samples collected from eight locations around the Andaman Islands, a remote, tropical archipelago between India and Myanmar.
The researchers isolated C. auris of two locations: a salt marsh swamp area where hardly any people go, and a beach with more human activity.
The C. auris Beach isolates were all multi-drug resistant and more closely related to the strains seen in hospitals compared to the isolates found in the swamp, Chowdhary said in a statement.
One isolate found in the swamp was not resistant to drugs and grew more slowly at high temperatures than the other isolates. This finding suggests that this isolate could be a “wilder” species C. auris, one that had not yet adapted to the high body temperatures of humans and other mammals, Casadevall said.
The study provides some support for the global warming hypothesis, as it was identified in the first place C. auris in a natural environment, which is a prerequisite for the hypothesis, the editorial said. In addition, the “wilder” isolate could be some sort of missing link between wild animals C. auris and cause infections in hospitals.
Yet the study does not prove that C. auris lives naturally in the Andaman Islands, or whether it originated there. It is possible that the microbe was introduced by humans, especially in the beach location where there was more human activity. In addition, some researchers have questioned whether the microbe may have been carried by ocean currents from areas where human waste was dumped in the water to the shores of the Andaman Islands, Casadevall said.
The new findings are likely to spur more researchers to look for it C. auris in natural settings, and to compare wild species with those from hospitals, Casadevall said. Studies could also investigate whether it is wild C. auris Isolates with less heat tolerance could “evolve” in a lab environment to grow at higher temperatures, providing more support for the global warming hypothesis, the editorial said.
If that is indeed demonstrated C. auris came from the wild, and that global warming was a factor in the jump to humans, researchers are concerned that more pathogens could make the same jump. Many fungal organisms are harmful to insects and amphibians, but not humans because of our high body temperature, Casadevall noted.
“If this idea is validated … we should start mapping more of these pathogens out there so we don’t get surprised,” as we were surprised by the new coronavirus, Casadevall said.
Originally published on Live Science.