Cases of a deadly treatment-resistant fungal infection jump dramatically

By Lisa Marie Basile | Fact-checked by Barbara Bekiesz
Published March 20, 2023

Key Takeaways

  • Cases of an emerging, highly contagious fungal infection caused by Candida auris (C. auris) are on the rise, with a mortality rate of 30 to 60 percent.

  • Patients most at-risk are those who’ve just had surgery, use broad-spectrum antibiotics and antifungal medications, are in long-term healthcare facility settings, and those with indwelling devices or diabetes.

  • C. auris is challenging to identify since only specific laboratory methods can isolate it.

New research in the Annals of Internal Medicine has found that an emerging, highly contagious fungal infection caused by Candida auris (C. auris) is on the rise. 

Numbers rose sharply in the past few years, the authors wrote—from a 44 percent increase in 2019 to a 95 percent increase in 2021. In 2021, colonization screening volume jumped by more than 80 percent, while screening cases jumped 200 percent. Additionally, there were three times as many cases of treatment-resistant C. auris in 2021 than in the two years prior. For 2022, between January and December, there were 2,377 clinical cases and 5,754 screening cases.[] 

The number of C. auris cases may be even higher, though. “Screening is not conducted uniformly across the United States, so the true burden of C auris cases may be underestimated,” the researchers also noted.

A look at Candida auris 

“Auris” is Latin for “ear.” Candida auris was first identified in Japan in 2009, after being isolated from an external ear canal discharge from a patient, as reported in Microbiology and Immunology. However, strains were identified 1996 in South Korea. The pathogen was first seen in the United States in 2016.[][] 

Infection by C. auris is invasive, affecting the whole body, including the bloodstream and wounds. “It also has been isolated from respiratory and urine specimens, but it is unclear if it causes infections in the lung or bladder,” the Centers for Disease Control and Prevention (CDC) reports.[] 

C. auris isolates have been found in a wide range of specimen types, such as “typically sterile body fluids, respiratory sections, urine, bile, tissues, wounds, and mucocutaneous swabs,” report researchers in the Journal of Clinical Microbiology.[]

C. auris may behave differently than other Candida species. By efficiently colonizing the skin, C. auris contaminates the patient's environment, and this results in rapid nosocomial transmission and outbreaks of systemic infections.[] “However, the role of skin microbiota in the colonization and pathogenesis of C. auris remains to be explored,” researchers wrote in mSphere

The fungus can live on surfaces for weeks, says the CDC.[] 

While most fungal infections can be cleared up fairly easily, C. auris is more complex—and can be fatal, especially if patients have other serious health conditions. The mortality rate is 30 percent to 60 percent, according to Microbial Cell.[]

C. auris isolates from different regions (all of which emerged independently around the same time) are quite different from one another. Some researchers think it emerged from a common ancestor.[] 

C. auris and transmission 

C. auris has occurred in patients of all ages, from infants to older adults. ​​Symptoms tend to look like fever and chills, especially when persistent after treatment for bacterial infection. 

Specifically worrisome is that C. auris transmission most often takes place in healthcare settings, especially in long-term care facilities. It’s commonly seen in patients who have indwelling devices—like tracheostomy tubes, urinary catheters, or feeding tubes—and in people who use mechanical ventilators.

As with other types of Candida infections, patients who have recently had surgery, have diabetes, or use broad-spectrum antibiotic and antifungal medications may be at higher risk for C. auris, notes the CDC. 

But the spread may become farther-reaching, according to Susan Huang, medical director of epidemiology and  infection prevention, UCI Health. “Similar to other antibiotic-resistant pathogens, the concern is that the spread in healthcare [settings] will form a gateway to broader community settings, such as those with complex medical conditions who are recovering at home or need frequent outpatient clinical care,” Huang says.

“Its contagiousness is similar to another major antibiotic-resistant pathogen, methicillin-resistant Staphylococcus aureus, or MRSA. It spreads easily from the nose and skin to nearby objects and can spread by touching someone who has it or touching something that is contaminated,” Huang explains.

Why are there so many C. auris infections?

Research in Annals of Internal Medicine suggests that the spread of C. auris 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 [infection prevention and control] measures.”

There are other theories as to why C. auris has spread so extensively in hospital settings. A review in Microorganisms also suggested that the environmental presence of azoles or a possible effect of climate change could be contributing to the sudden emergence of C. auris.[]

C. auris treatment

Generally, C. auris infections are treated with echinocandins, a group of antifungal medications used for invasive candidiasis, especially in critically ill patients. Echinocandins are also the first-line treatment for Candida infections in general. Nonetheless, with the recent increase in drug-resistant cases of C. auris, infections can persist even with antifungal treatments. 

The CDC recommends that physicians consult with a healthcare provider with a background in treating patients with fungal infections. Additionally, treating patients with a C. auris infection may require high doses of multiple classes of antifungals.[] 

Prior to proper management, C. auris must be identified accurately. It can be diagnosed by using blood culture or body fluids, but identifying it has proven tricky, as only specific laboratory methods can isolate it. 

In fact, C. auris is often misidentified when using traditional phenotypic methods for yeast identification, according to the CDC. Some of the common methods that yield misidentifications include VITEK 2 YST, API 20C, BD Phoenix yeast identification system, and MicroScan. A table of all misidentifications can be seen here. Candida haemulonii comes up frequently.[] The CDC says there are a few methods for identifying C. auris, but “the most reliable way to identify C. auris is matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). If you have a MALDI-TOF MS in your lab, ensure that C. auris is included in the database.”[]

Also key? “Ensuring healthcare providers in hospitals and nursing homes follow recommended protocols, such as cleaning their hands and wearing gowns and gloves, when caring for patients who have C. auris,” Huang adds. There are CDC-recommended protocols in place for C. auris prevention in healthcare facilities. 

If you suspect your patient has C. auris infection, the CDC urges you to contact state or local public health authorities as well as the CDC. You should email immediately. 

In the end, “Prevention, surveillance, and monitoring is so important, as is increasing efforts to discover new antibiotic therapies,” Huang says. 

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