Researchers in China identified a new fungal pathogen named Rhodosporidiobolus fluvialis in clinical samples from two hospital patients.
This fungus, not previously known to infect humans, was resistant to several main antifungal drugs at body temperature. At this temperature, the fungus produced more dangerous mutants that caused severe disease in lab mice.
Study Findings
As reported by LiveScience, the discovery was made after studying fungi samples from patients in 96 hospitals across China between 2009 and 2019.
Out of 27,100 strains of fungi analyzed, only R. fluvialis had never been seen in humans before.
The fungus was found in the blood of two unconnected patients who had serious underlying health conditions.
One patient, a 61-year-old, died in an ICU in Nanjing in 2013.
The other patient, an 85-year-old, died in 2016 after being treated in an ICU in Tianjin.
The report does not specify whether the fungal infection directly contributed to their deaths.
Both patients were treated with common antifungal drugs like fluconazole and caspofungin. Lab studies later showed that R. fluvialis is resistant to these drugs.
David Denning, a professor of infectious diseases at the University of Manchester, called this discovery "remarkable and truly unexpected," expressing concerns about future implications.
Impact of Global Warming
The study supports the idea that global warming can help new fungal pathogens evolve.
Rising global temperatures have caused fungi to adapt and move to new areas, making them more likely to infect humans. This has led to the emergence of new pathogens, including the drug-resistant Candida auris, identified in more than 40 countries since its discovery in 2009.
Experiments and Findings
In experiments, researchers infected immunocompromised mice with R. fluvialis and found that some fungal cells quickly evolved to become more aggressive.
At human body temperature (98.6°F or 37°C), the yeast mutated 21 times faster than at room temperature (77°F or 25°C). The heat also made the yeast more likely to become drug-resistant.
When exposed to the antifungal drug amphotericin B, the yeast developed resistance more quickly at body temperature than at room temperature.
Future Concerns
If yeasts like R. fluvialis become more dangerous and drug-resistant at higher temperatures, global warming could drive the evolution of new, harmful fungal pathogens.
Some scientists caution against jumping to conclusions about R. fluvialis specifically.
Matthew Fisher, a professor of fungal disease epidemiology at Imperial College London, noted that there is no evidence of R. fluvialis spreading widely, suggesting that the patients may have been exposed to unsurveyed environments where these yeasts live.
