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.

Tracking candida auris | candida auris | fungal diseases | cdc.

 

 

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.

Candida auris—a mysterious and tenacious enemy | nih: national institute of allergy and infectious diseases.

Satoh K, Makimura K, Hasumi Y, Nishiyama Y, Uchida K, Yamaguchi H. Candida auris sp. nov., a novel ascomycetous yeast isolated from the external ear canal of an inpatient in a Japanese hospital. Microbiol Immunol. 2009;53(1):41-44.

 

 

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.

General Information About Candida auris. CDC. November 13, 2019.

 

 

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.

Spivak ES, Hanson KE. Candida auris: an emerging fungal pathogen. J Clin Microbiol. 2018;56(2):e01588-17.

 

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.

Tharp B, Zheng R, Bryak G, et al. Role of microbiota in the skin colonization of Candida auris. mSphere. 2023;8(1):e00623-22.

“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.

Candida auris. Healthcare Professionals FAQ. CDC. April 9, 2021.

 

 

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.

Sharma M, Chakrabarti A. On the origin of Candida auris: ancestor, environmental stresses, and antiseptics. mBio. 2020;11(6):e02102-20.

 

 

 

 

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.

 

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.

Sabino R, Veríssimo C, Pereira ÁA, et al. Candida auris, an agent of hospital-associated outbreaks: which challenging issues do we need to have in mind? Microorganisms. 2020;8(2):181.

 

 

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. 

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.

Identification of candida auris | candida auris | fungal diseases | cdc.

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.”

Information for laboratory staff | fact sheets | candida auris | fungal diseases | cdc.

 

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 candidaauris@cdc.gov immediately. 

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