A microbiological culture of the yeast Candida auris which can be responsible for infections.
Image Credit: Scientific Frontline / AI generated
Scientific Frontline: Extended "At a Glance" Summary: Candida auris
The Core Concept: Candida auris is an emerging, multidrug-resistant pathogenic yeast capable of causing life-threatening invasive infections in humans, serving as a potential harbinger of other climate-adapted fungal pathogens.
Key Distinction/Mechanism: Unlike most fungal species that cannot survive at normal human body temperatures, Candida auris thrives at 37 degrees Celsius and up to 47 degrees Celsius—a thermal tolerance hypothesized to be driven by climate change or anthropogenic environmental shifts—while also persisting on hospital surfaces and resisting multiple antifungal medications.
Origin/History: First discovered in 2009 in a patient's ear in Japan (hence the name auris, meaning ear), the fungus subsequently emerged simultaneously across multiple distinct genetic lineages on several continents, indicating a globally active selective pressure.
Major Frameworks/Components:
- Thermal Adaptation Hypothesis: The theoretical model proposing that rising global temperatures select for thermotolerant fungi capable of overcoming the mammalian 37-degree Celsius thermal barrier.
- Clinical Severity and Mortality: Documenting bloodstream infection mortality rates ranging from 20% to 67% (averaging around 52% globally) in immunocompromised hospital and care-home patients.
- Integrated Early-Warning Systems: Frameworks emphasizing systematic surveillance of fungi in soil, water, air, and healthcare facilities through the collaboration of environmental monitoring, climate research, evolutionary biology, and medicine.
Branch of Science: Microbiology, Mycology, Evolutionary Biology, Infectious Diseases, Epidemiology
Future Application: Development of theoretical predictive models and advanced diagnostic infrastructures to forecast, monitor, and preempt emerging fungal threats before major outbreaks occur.
Why It Matters: It highlights the escalating global threat of climate-driven pathogenic fungi, underscoring the urgent need for enhanced multidisciplinary surveillance, laboratory diagnostics, and novel antifungal drug development.
Candida auris, a fungus that is life-threatening to humans, has spread rapidly across the globe. Researchers at the University of Würzburg suspect this may be due to rising temperatures.
Why has the yeast Candida auris become a dangerous pathogen worldwide in just a few years? This question is on the minds of many researchers. Carla Schuh and Chaitanya Gokhale from the Biocenter at the University of Würzburg have now summarized the current state of knowledge in a review article in the journal mSphere. To that end, they analyzed around 180 studies by other researchers.
The two researchers have a theory: in their view, it could be that climate change is what made the fungus infectious in the first place.
Why do they think this? Of the estimated three to five million species of fungi on Earth, only a few hundred are capable of infecting humans. “This is partly because most fungi cannot grow at a body temperature of 37 degrees Celsius,” says Carla Schuh. However, climate change could lead to many fungi adapting to higher temperatures—and thus being able to colonize the human body.
Original Habitat of the Fungus Unknown
Important: The Würzburg study does not prove that climate change has actually caused the increased infectivity of Candida auris. However, the researchers have found numerous indications in the studies reviewed that support this explanation.
They emphasize that the original habitat of Candida auris remains unknown to this day. Possible habitats include coastal areas, wetlands, or other saline environments. “This is another reason why there are several possible explanations for why the fungus appeared so suddenly and spread so rapidly,” says Chaitanya Gokhale. In addition to climate change, other man-made environmental changes are also being discussed, such as the use of fungicides in agriculture.
High Mortality Rate in Cases of Blood Infection
Candida auris was first discovered in 2009 in Japan, in a patient’s ear. This is where its name comes from, which literally translates as “yeast of the ear.” Within a few years, the fungus was found simultaneously on several continents in different genetic lineages. In evolutionary biology, this is an indication of a globally active selective factor, such as climate change.
The fungus grows readily at 37 degrees Celsius and can even withstand temperatures of up to 47 degrees Celsius. Its closest relatives cannot do this. Furthermore, it manages to survive on surfaces in hospitals for extended periods, and it is often resistant to several antifungal drugs at the same time.
All of this combined makes Candida auris life-threatening for immunocompromised people, such as hospital patients or nursing home residents. If it enters the bloodstream, the mortality rate—depending on the study—ranges between 20 and 67 percent. For many countries, the figure is around 52 percent. During an outbreak in Europe with 140 confirmed cases, 41 percent of those affected died within a month.
Fungal Infections on the Rise Worldwide
The review article from Würzburg also examines global research findings on how environmental changes influence the spread of fungal diseases. The examples range from Cryptococcus gattii and Aspergillus fumigatus to other fungal species that are colonizing new regions or frequently developing resistance.
“The research community agrees that fungal infections are becoming increasingly significant worldwide. However, the exact causes and the role of individual factors remain the subject of heated debate,” reports Carla Schuh.
Early-Warning Systems for New Pathogens
Many researchers conclude from their findings, above all, that there is a need for better surveillance—to detect new pathogens as early as possible, before major outbreaks occur.
They propose systematically monitoring fungi in soil, water, the air, and hospitals. This, they say, requires close integration of environmental monitoring, climate research, evolutionary biology, and medicine.
Developing such early-warning systems and preventive measures would require substantial investment in diagnostics, laboratory infrastructure, and drug development. As a first pass, theoretical models could then help predict which species might become problematic in a cost-effective way.
“Given the shift in Candida infection dynamics, investing in and developing such predictive frameworks is imperative, as we expect other closely related species to follow this trajectory,” say the Würzburg researchers.
Published in journal: mSphere
Title: Candidozyma auris (Candida auris) as a harbinger of novel fungal pathogens
Authors: Carla E. Schuh, and Chaitanya S. Gokhale
Source/Credit: Universität Würzburg | Robert Emmerich
Edited by: Scientific Frontline
Reference Number: mcb102226_01
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