Cause for Concern: Emerging Pan-resistant Candida auris

Image result for candida auris
photo courtesy of UCSF Health

Candida auris was first described in 2009 and was first reported in the United States in 2016.(1)  It is a member of a growing group of yeasts that can cause candidiasis, yeast infections that are normally of little consequence, and treatable through a number of anti-fungal medications.  Nosocomial candidiasis, however can easily infect ports installed in the body for medical reasons, and then progress to candidemia, a potentially deadly blood infection.(2)  Candida auris is remarkable in that it is often drug resistant and difficult to identify without specific technologies that are not readily available in a clinical setting, namely PCR and MALDI-TOF mass spectrometry.(3)

As of June 2019, a clinical outbreak of Candida auris was reported in New York.  Of more than 800 patients, three were confirmed to have Candida auris infections resistant to all three classes of commonly prescribed anti-fungal medications; fluconazole, amphotericin B, and echinocandins.  All three patients had Candida infections that exhibited fluconazole resistance and two were found to be amphotericin B resistant.  None had received echinocandins prior to their diagnosis of being infected with Candida auris.  Indeed, isolates from all patients showed an initial sensitivity to echinocandin therapy, and were thus treated.  Resistance was not detected until after completion of echinocandin treatment, indicating that the patient isolates became pan-resistant to all three medications during therapy.  Investigators found no indications of successful patient-to-patient transmission of this pan-resistant strain after the study was completed.(1)

The emergence of pan-resistant Candida auris is concerning in that, with traditional testing methods, it is easily mistaken for other, more common Candida species, even on differential media.(4)  It can cause invasive candidiasis in at-risk populations, contribute to widespread Candida outbreaks, and progress to candidemia just as readily.  However, as a potentially multi-drug-resistant microorganism, each of the above situations takes on an increased urgency.  Even now, four years after the New York outbreak was identified, the fact that pan-resistant Candida auris isolates appear so rare should be of little consolation. 

The technology required for Candida auris identification must be advanced.  Even with the promising development of a new class of anti-fungal medications and more prudent anti-fungal prescription practices by healthcare professionals, the average healthcare facility must be able to perform rapid, accurate identification.  Until this happens, our healthcare system will continue losing time, money, and lives to Candida auris outbreaks that have caused up to 60% mortality rates in other healthcare facilities around the world.(5)

Written by Dave Cochran, Technical Service and Instrumentation Specialist

References:

(1) Candida auris Isolates Resistant to Three Classes of Antifungal Medications — New York, 2019

Morbidity and Mortality Weekly Report (MMWR), January 10, 2020 / 69(1);6–9

https://www.cdc.gov/mmwr/volumes/69/wr/mm6901a2.htm?s_cid=mm6901a2_w

(2) About Invasive Candidiasis

https://www.cdc.gov/fungal/diseases/candidiasis/invasive/definition.html

(3) General Information about Candida auris

https://www.cdc.gov/fungal/candida-auris/candida-auris-qanda.html

(4) Candida auris: A drug-resistant yeast that spreads in healthcare facilities

https://www.cdc.gov/fungal/candida-auris/pdf/C-Auris-Lab-Workers-FactSheet-H.pdf

(5) Novel antifungal shows early promise against Candida auris

http://www.cidrap.umn.edu/news-perspective/2019/04/novel-antifungal-shows-early-promise-against-candida-auris

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