Scientists have discovered that the deadly fungus Candida auris survives antifungal drugs by creating multiple copies of its entire genome, following a laboratory accident where cell plates were left incubating too long. The pathogen carries a 45 percent bloodstream death rate and has emerged globally across more than 60 countries.
An accidental oversight in a laboratory has revealed a previously unknown survival trick used by one of the world’s most concerning superbugs. Researchers testing drug resistance found that a researcher left plates of cells incubating longer than the required test period. When they returned, they discovered that cells had unexpectedly continued to grow despite high concentrations of antifungal medication.
That accidental delay brought to light a mechanism the research team terms bet-hedging
. Instead of relying on a single genetic adaptation, the fungus creates multiple versions of its entire genome to increase its chances of mutating and evading treatment.
University of Exeter and City St George’s Researchers Identify the Genome Copying Mechanism
The discovery was made by a team led by the University of Exeter and City St George’s, University of London. Their findings, published in Nature Communications, stem from investigating why standard antifungal drugs failed to clear infections in two critically ill patients in London whose laboratory tests initially rated the pathogen as susceptible.
When exposed to high doses of anidulafungin in the lab, surviving cells emerged in two distinct populations: slow-growing cells that tolerated the drug and faster-growing cells that resisted it. Both groups possessed extra copies of their full set of DNA. The faster-growing colonies also carried mutations in a gene named Crazy-one
(CRZ1), which governs cell wall synthesis.
Candida auris is rare in the general population, but it’s a deadly threat to patients in intensive care units. It clings to patient skin and surrounding equipment, and can be transmitted from person to person – it’s incredibly hard to eradicate. If infection enters a vulnerable patient’s blood stream, there is a 45 per cent death rate.
Dr Hugh Gifford, Clinical lecturer at the University of Exeter’s MRC Centre for Medical Mycology and intensive care physician
Funding for the research came primarily from the Medical Research Council, with support from the NIHR Biomedical Research Centre: Exeter.
Global Spread and ICU Outbreaks Highlight the Public Health Threat
First described in 2008 with origins that remain a mystery, C. auris has spread to more than 60 countries across every continent. The pathogen sits on the World Health Organization’s critical priority fungal pathogens list as a recognized global public health threat.
Hospital environments face severe disruption when outbreaks occur. One intensive care unit in the UK had to close entirely and undergo complete refurbishment to stop an outbreak, while a separate containment effort was estimated to cost £1 million.
Clinical case numbers continue to climb in institutional settings. In the United States, the CDC counted 6,304 clinical cases in 2024, representing the highest annual total recorded to date.
Scientific Reports published a separate study detailing a 28-year-old patient in Kenya who developed a hospital-acquired surgical site infection resistant to all four major classes of antifungal drugs. Genome sequencing revealed that this strain carries resistance mutations distinct from a previous pan-resistant case documented in 2022, suggesting the lineage independently evolved pan-resistance.
resistance to four major antifungal classes highlights the escalating threat of untreatable fungal infections, particularly in settings with limited access to novel antifungal agents.
Study authors, writing in Scientific Reports
While fully untreatable infections remain rare, researchers warn that the pathogen’s capacity for step-wise adaptation undermines existing medical defenses.
New and emerging human fungal infections, like Candida auris, essentially have a Swiss Army Knife of genetic adaptations.
Professor Tihana Bicanic, City St George’s, University of London
Research teams are currently working to improve clinical detection and hospital eradication protocols.