New and deadly drug-resistant fungus emerging in US

Physicians should be on alert for patients with risk factors for Candida auris, an emerging and potentially deadly fungus that causes bloodstream and intra-abdominal infections, according to infectious disease specialists at the CDC.

“Although only recently documented in the United States, C. auris could become a major cause of invasive candidiasis unless its spread is contained,” warned CDC medical epidemiologist Snigdha Vallabhaneni, MD, MPH, and coauthors in a new commentary in Annals of Internal Medicine.

In the United States, 685 confirmed cases of C. auris (with another 30 probable cases) had been documented as of May 31, predominantly in the New York City area, New Jersey, and the Chicago area. 

Among patients with invasive infection (primarily the immunocompromised), 40% die within 30 days.

Once transmitted, C. auris can colonize several body sites, primarily the skin and nostrils. In addition to bloodstream and intra-abdominal infections, other reported sequelae include endocarditis, surgical site infections, osteomyelitis, and endophthalmitis.

Why C. auris is novel

Candida auris is different from other common Candida species in two ways:

• Compared with other human-pathogenic yeasts, the drug resistance of C. auris is unprecedented. In the United States, 90% of C. auris isolates are resistant to fluconazole, more than 40% are resistant to amphotericin B, and about 2% are resistant to echinocandins. To make matters worse, many strains are resistant to two or even all three classes of antifungal agents.

• C. auris is commonly transmitted between patients in healthcare settings. An outbreak in a single medical center can spread through its networks of facilities. In New York City, C. auris spread among interconnected long-term care facilities and hospitals, where environmental surfaces and devices were found to be contaminated.

“From an infection control perspective, C. auris acts more like a multidrug-resistant, healthcare-associated bacteria than like a typical yeast. It is a new bug using old tricks mastered by some well-known, multidrug resistant organisms,” Dr. Vallabhaneni and coauthors observed.

Risk factors for fungi

As noted above, physicians should be aware of the risk factors for C. auris infection.

A primary risk factor is receiving healthcare in high-acuity, post-acute care settings—including long-term acute care hospitals and skilled nursing facilities with ventilator units. Other risk factors include history of stroke or other severe neurologic conditions, receiving tracheostomies and percutaneous feeding tubes, and the inability to perform any activities of daily living.

“In addition, frequent hospitalizations and receipt of multiple courses of very broad-spectrum antibiotics, like carbapenems, stand out as risk factors for C. auris colonization,” noted Dr. Vallabhaneni and coauthors.

Another known risk factor: A history of hospitalization in a country with C. auris transmission. Some infected US patients had been hospitalized overnight in India, Kenya, Kuwait, Pakistan, South Africa, United Arab Emirates, and Venezuela. Some of these patients were also colonized or infected with carbapenemase-producing, carbapenem-resistant Enterobacteriaceae.

Because of these risks, the CDC recommends that patients who’ve been hospitalized outside the United States in the previous year should be screened, especially those at risk of carrying carbapenemase-producing organisms. Some healthcare facilities are also screening patients who’ve been admitted to hospitals in highly affected areas of the United States.

Identification, diagnosis, and treatment

Early identification of C. auris is the key to controlling its spread. However, it can be difficult to detect. Candida auris can be easily misidentified for another organism when using traditional phenotypic methods for identifying yeasts.

Mass spectrometry using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and a reference organism database can differentiate C. auris from other Candida species. (The FDA OK’d the first MALDI-TOF test specifically for C. auris in late April 2018.)

In high-risk settings like long-term acute care hospitals, clinicians should also determine the species of yeast found in noninvasive sites, such as urine and respiratory specimens, according to the CDC.

For treatment, use echinocandins as initial therapy in most cases, although the CDC highly recommends consulting with an infectious disease specialist for managing these patients. For more detailed treatment information, see the CDC’s recommendations for identification, treatment, and infection prevention and control of C. auris.

Note: Candida auris infection is a nationally notifiable condition. Doctors, lab specialists, and other healthcare workers should report any cases to state or local public health authorities as well as the CDC (candidaauris@cdc.gov).