Some Candida auris isolates have been documented as resistant to three major classes of antifungal drugs—but the evidence does not show that every strain is untreatable, or that this happened “twice.” A 2020 CDC report described three New York patients whose isolates became resistant to all three classes after treatment. The report does not identify two separate events.
What the headline gets right—and what “twice” leaves unclear
The fungus is Candida auris, a yeast associated with healthcare settings, outbreaks, and invasive infections. The CDC report most directly relevant to the claim was published January 10, 2020, and described three chronically ill New York patients with isolates resistant to all three major antifungal classes. It did not document two distinct episodes or explain the word “twice.”
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The report’s finding concerns particular isolates from three patients, not all C. auris. It also describes resistance detected after antifungal treatment. That is evidence resistance emerged during therapy in these cases; it does not establish that this progression is universal or show how often it occurs.
Which antifungal drugs were involved?
In the CDC report, “pan-resistant” had a defined scope: resistance to a triazole, a polyene, and an echinocandin. These are three major antifungal classes, rather than every antifungal drug in existence.
#1 Best Overall
| Class | Example or description | What the CDC finding means |
|---|---|---|
| Triazoles | Includes azoles such as fluconazole | The tested isolate was classified as resistant to a triazole using the report’s laboratory criteria. |
| Polyenes | Includes amphotericin B | The tested isolate was classified as resistant to a polyene. |
| Echinocandins | A separate major antifungal class | The patients’ isolates were initially susceptible to echinocandins; resistance was detected after treatment. |
The CDC used tentative minimum inhibitory concentration (MIC) breakpoints and confirmatory testing to classify resistance. An MIC is a laboratory measure of how much drug is needed to inhibit a microorganism under test conditions; it is not, by itself, a prediction of an individual patient’s outcome.
How unusual were the New York cases?
The CDC report identified three patients with pan-resistant isolates among 801 people in New York State who had C. auris identified through clinical cultures or colonization screening by June 28, 2019. That is a historical, state-level surveillance count—not a current national estimate. The CDC said pan-resistant isolates remained rare in New York three years after the organism was first identified there.
Other figures in the same report show why resistance findings need a clear population and date attached. Among 277 tested first available clinical isolates with susceptibility results, 276 (99.6%) were fluconazole-resistant. Among 331 subsequent available isolates from infected patients with susceptibility results, 13 (3.9%) were echinocandin-resistant. Both percentages describe historical New York samples reported in 2020; neither should be read as a present-day prevalence estimate for the United States or elsewhere.
Does every C. auris strain resist all three classes?
No. Resistance varies among isolates and lineages. A 2019 review reported that isolates resistant to all three major classes had been observed in clades I, III, and IV, while resistance levels differed among clades; the cited data suggested clade II appeared less resistant. That does not mean every isolate in those clades is resistant, nor that a clade label alone determines a patient’s treatment options.
A 2024 review describes C. auris as an outbreak-capable pathogen associated with healthcare settings, persistence on patient skin and in the environment, invasive infections, and acquired antifungal resistance. Those features make surveillance and infection prevention important, but they do not turn the three-patient report into evidence that the species is uniformly drug-proof.
Did the resistant isolates spread to other people?
In the CDC investigation, no pan-resistant isolates were found among the contacts and facility environments examined. That finding is limited to those investigated contacts and sites. It does not show that C. auris cannot spread, or that pan-resistant isolates cannot spread in other circumstances.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What should readers take away?
- Pan-resistant C. auris has been documented, but the CDC’s 2020 report concerns three patients in New York and resistance to three major classes—not every antifungal drug.
- Those patients’ isolates were initially echinocandin-susceptible, with resistance detected after treatment; the cases do not establish a universal pathway or rate.
- Resistance differs among isolates and clades, so “the fungus is resistant to every major antifungal” is too broad if applied to the entire species.
- The report does not substantiate “twice” as a count of two events.
CDC MMWR: “Candida auris Isolates Resistant to Three Classes of Antifungal Medications — New York, 2019” (published January 10, 2020); Welsh et al., 2019 review of clade variation; 2024 review of C. auris phenotypic and strain variation.
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