Candida auris is an emerging fungal threat that was first reported in 2016. In order to understand the extent of its spread in the United States, a team of researchers analyzed recent changes in the epidemiology of C. auris occurring from 2019 to 2021 using national surveillance data.

The study found that cases of C. auris, rose drastically between 2019 and 2021 reflecting increased transmission. More specifically, a total of 3270 clinical cases and 7413 screening cases of C. auris were reported in the United States through December 31, 2021. The percentage increase in clinical cases grew each year, from a 44% increase in 2019 to a 95% increase in 2021.

The researchers also noted an increase in echinocandin-resistant cases and evidence of transmission, which is particularly concerning because echinocandins are first-line therapy for invasive Candida infections, including C. auris. These findings emphasize that improved detection and infection control practices are urgently needed to prevent the spread of C. auris.

The report is published in Annals of Internal Medicine in the paper, “Worsening spread of Candida auris in the United States, 2019 to 2021.”

The Centers for Disease Control and Prevention (CDC) rated C. auris as an “urgent threat,” the highest level of concern, because it is often multidrug-resistant; spreads easily in healthcare facilities; and can cause severe, invasive infections with high mortality rates. Most transmission occurs in healthcare facilities, especially among residents of long-term care facilities or among persons with indwelling devices or mechanical ventilators.

Researchers from the CDC used national surveillance data on clinical and screening C. auris cases reported to state and local health departments and the CDC to describe recent changes in the U.S. epidemiology of C. auris between 2019 and 2021. They also examined data from CDC’s Antimicrobial Resistance Laboratory Network (AR Lab Network).

In addition to the data showing an increase in clinical cases each year, from a 44% increase in 2019 to a 95% increase in 2021, they also report that colonization screening volume and screening cases increased in 2021 by more than 80% and more than 200%, respectively. The number of C. auris cases that were resistant to first-line treatment in 2021 was about three times that in each of the previous two years.

According to the authors, the timing of this increased C. auris spread and findings from public health investigations suggest it may have been exacerbated by pandemic-related strain on the health care and public health systems, which included staff and equipment shortages, increased patient burden and disease severity, increased antimicrobial use, changes in patient movement patterns, and poor implementation of non–COVID-19 IPC measures.