CDC Reports Several Cases of Drug-Resistant Fungal Infection in Two U.S. Cities

The multidrug-resistant fungus Candida auris can cause severe illness in hospitalized patients or in individuals with weakened immune systems.

Now, researchers have identified various cases of patients in hospitals and nursing homes contracting a highly drug-resistant strain of C. auris that may have spread person-to-person—the first reported cases of this kind in the United States, reports Ed Cara for Gizmodo. The results were released in the Centers for Disease Control and Prevention's (CDC) online journal called Morbidity and Mortality Weekly Report on July 23.

The CDC considers the fungus, first discovered in 2009, an emerging pathogen. C. auris causes illness when it contaminates wounds of vulnerable patients, reports Shawna Williams for The Scientist. When the infection spreads to various parts of the body and the bloodstream in immunocompromised people, it has a 30 percent mortality rate, Gizmodo reports.

The C. auris outbreaks identified in the new report happened between January and April this year in Washington, D.C. and Texas. While the two outbreaks were unrelated to each other, they both occurred within long-term care facilities and hospitals where patients had extended stays. Many of the patients had strains of C. auris that were pan-resistant, meaning resistant to all antifungals, or resistant to echinocandins, a potent class of antifungals used in the most severe cases of infection, reports Gizmodo.

Out of 101 C. auris cases in Washington D.C., three cases were totally resistant to the three classes of antifungal medications. In Texas, out of the 22 identified cases, two were resistant to all three antifungal medications. Five cases were resistant to two out of the three medications, reports Alexandria Larkin for CBS News.

"This is really the first time we've started seeing clustering of resistance," says the CDC report’s first author Meghan Lyman, a medical officer in the CDC's Mycotic Diseases branch, to CBS News.

Pan-resistant cases of fungal infections have been seen before in the U.S., but they were isolated cases that occurred after previous treatments of echinocandins created a more resistant type of fungus, reports The Scientist. However, in the new outbreaks, the patients were not treated with antifungal drugs before the fungal infection, suggesting that the strain of C. auris that the patients had was already pan-resistant, reports Helen Branswell for STAT News.

"These cases are ones where the options are really limited,” Lyman tells STAT News. “There are few treatment options for these patients who have clinical infections. And the fact that now it can spread, it's not just in patients who are already getting treatment, means that a greater proportion of patients may have pan-resistance and [may] develop clinical infections that are potentially untreatable.”

Three classes of antifungal drugs used for treating Candida infections include azoles, polyenes, and echinocandins. Eighty-five percent of C. auris cases detected are resistant to azoles, and 39 percent are resistant to polyenes, reports STAT News. Ninety-nine percent of C. auris cases respond to echinocandin treatments, so they are used whenever the drug-resistant fungus is detected.

C. auris is alarming to healthcare experts because some strains do not respond towards commonly used antifungal treatments, and specialized laboratory methods are needed to identify strains accurately. Patients who are receiving long-term care, have insertable medical equipment such as catheters, or have taken antibiotics or antifungal medications are the most at-risk for infection.

Once C. auris establishes itself in medical environments, it rapidly spreads because it can be difficult to remove from contaminated surfaces and objects, Gizmodo reports. Some experts suspect that the coronavirus pandemic may have amplified the spread of C. auris with the shortages of personal protective equipment, the New York Times reports.

A third of the infected patients in both Texas and Washington, D.C. died within 30 days. But because the infections occurred in patients who were already severely ill, it is unknown if the fungal infection caused or simply contributed to the deaths, reports Andrew Jacobs for the New York Times.

For now, experts suggest testing patients with infections for resistance towards antifungals. Facilities should be vigilant on containing spread as much as possible as more work is needed to see how pan-resistant infections could be treated in the future.

"With all this spread that we've been seeing across the country, we're really encouraging health departments and facilities to be more proactive instead of reactive to identifying Candida auris in general. Because we've found that controlling the situation and containing spread is really easiest when it's identified early before there's widespread transmission," Lyman tells STAT News.

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a daily correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.