Candida auris is a drug-resistant fungus that causes serious infections in hospitalized patients. First identified in Japan in 2009, it has since spread to healthcare facilities across the globe and is considered an urgent public health threat. What makes it unusual is a combination of traits rarely seen together in fungi: it resists multiple antifungal medications, survives on hospital surfaces for weeks, and spreads easily from patient to patient.
Why C. Auris Is Different From Other Fungi
Most Candida species (the broader family of yeasts that cause common infections like thrush) are genetically similar to one another. C. auris is not. It sits on a distant branch of the fungal family tree, classified in an entirely separate group from the species doctors typically encounter. That genetic distance helps explain why it behaves so differently.
C. auris thrives at temperatures up to 108°F (42°C), which is higher than most fungi can tolerate and close to human fever temperatures. It also survives in environments several times saltier than the ocean. These traits suggest the organism may have adapted to harsh conditions long before it began infecting people, though exactly what triggered its emergence in healthcare settings remains an open question.
Perhaps its most concerning feature is persistence. C. auris readily colonizes human skin along with the nose, ears, mouth, and other body sites. Once on a surface, whether skin or a hospital bed rail, it can linger for weeks. In lab testing, the fungus survived on plastic, steel, and other common hospital materials for more than three weeks in both wet and dry conditions. It also forms biofilms, sticky clusters of cells that are especially hard to remove and that allow it to flourish on surfaces.
How It Spreads in Healthcare Settings
C. auris spreads primarily through contact in hospitals and long-term care facilities. A colonized patient (someone carrying the fungus on their skin without being sick) can shed it onto surfaces, medical equipment, and the hands of healthcare workers, who then transfer it to the next patient. This person-to-person chain of transmission is unusual for a pathogenic fungus. Most Candida infections come from organisms already living inside a person’s own body, not from another patient.
The problem is compounded by the fact that many standard hospital disinfectants don’t kill it. Products that rely solely on quaternary ammonium compounds, a common class of cleaning agents, are not effective against C. auris. The CDC recommends using only disinfectants on the EPA’s List P, a specific registry of products tested and approved for this organism. Rooms housing colonized or infected patients need thorough daily cleaning, and all shared equipment must be disinfected after every use.
Case numbers in the United States have been climbing. In 2024, the number of reported clinical cases increased nationally, with transmission continuing in some regions and the fungus spreading into new geographic areas.
Who Is at Risk
C. auris overwhelmingly affects people who are already seriously ill. Infections and colonization occur most commonly in patients with complex, overlapping medical conditions who have spent extended time in healthcare facilities. Intensive care unit stays, mechanical ventilation, and long-term use of medical devices like central lines and catheters are key factors. In one large U.S. study of C. auris hospitalizations from 2017 to 2022, roughly 75% of cases involved an ICU stay, and mechanical ventilation was used in 43%.
Healthy people in community settings face essentially no risk. This is a hospital-acquired infection tied to prolonged, intensive medical care.
Symptoms and How It’s Identified
The symptoms of a C. auris infection are not distinctive. They depend on where in the body the infection takes hold and can range from a mild ear infection to a life-threatening bloodstream infection. Fever and chills that don’t improve with antibiotics are common signs of invasive candidiasis, but nothing about the symptoms alone points specifically to C. auris. Many patients carry the fungus on their skin or in their bodies without developing any infection at all, though they can still pass it to others.
Identifying C. auris in the lab is one of the biggest challenges. Standard laboratory methods frequently misidentify it as a different Candida species. Accurate identification requires advanced technology: either mass spectrometry (a technique that identifies organisms by their molecular fingerprint) or DNA sequencing. Rapid PCR-based tests can also detect C. auris genetic material directly from patient samples within hours. Without these tools, infections can go unrecognized, allowing the fungus to spread undetected through a facility.
Drug Resistance and Treatment
C. auris is resistant to fluconazole, the most widely used antifungal drug, in the vast majority of cases. Many isolates are also resistant to a second class of antifungal, and some U.S. strains have been found resistant to all three major classes of antifungal medications. That leaves doctors with extremely limited options for the most resistant cases.
The first-line treatment for adults and children over two months old is a class of IV antifungal drugs called echinocandins. These work for many patients, but not all. When susceptibility testing shows echinocandin resistance, or when a patient doesn’t improve after five days on treatment, doctors typically switch to a different IV antifungal. For the rare cases where the fungus is resistant to every available drug, investigational medications still in clinical development may be considered.
Mortality Rates
Invasive C. auris infections are dangerous. A CDC analysis of U.S. hospitalizations from 2017 to 2022 found an overall crude mortality rate of 34% among patients with C. auris infections. For bloodstream infections specifically, the mortality rate was 47%, nearly one in two patients. Nonbloodstream infections carried a lower but still substantial mortality rate of 31%.
These numbers reflect the reality that C. auris patients are typically very sick to begin with, making it difficult to separate how much of the mortality is caused by the fungus itself versus the underlying conditions. Still, the combination of a vulnerable patient population and limited treatment options makes C. auris one of the most serious fungal threats in modern healthcare.