Critical care units and long-term care facilities are on alert for cases of Candida auris, a novel fungal infection that is both dangerous to vulnerable patients and difficult to eradicate. The increased profile of C. auris is not a welcome development but is no surprise to critical care physicians.
This pathogen was first identified in 2009 and has since been found in increasing numbers of patients all over the world. As expected, cases of C. auris are on the rise in the United States.
The Centers for Disease Control and Prevention stated “Candida auris is an emerging fungus that presents a serious global health threat.” This is an opportunistic pathogen that hits critically ill patients and those with compromised immunity.
On March 29, 2019, CDC reported that confirmed clinical cases of C. auris in the United States have more than doubled over the past year, from 257 cases in 2018 to 587 cases with an additional 1,056 colonized patients identified as of February 2019. “Most C. auris cases in the United States have been detected in the New York City area, New Jersey, and the Chicago area. Strains of C. auris in the United States have been linked to other parts of the world. U.S. C. auris cases are a result of inadvertent introduction into the United States from a patient who recently received health care in a country where C. auris has been reported or a result of local spread after such an introduction.”
Case reports have found a mortality rate of up to 50% in patients with C. auris candidemia. The total number of cases is still small, but the trajectory is clear. The hunt is on in labs all over the world for optimal treatments and processes to handle outbreaks.
Jeniel Nett, MD, an infectious disease specialist, and a team of investigators at the University of Wisconsin, Madison, have focused their research on the characteristics of C. auris and its progression in patients and in medical facilities.
According to Dr. Nett, it’s not clear why this emerging threat has cropped up in multiple locations globally. “Candida auris was first recognized in 2009, in Japan, and relatively quickly we saw emergence of this species in relatively distant locations,” she said, adding that independent clades in these locations ruled out transmission as the source of the multiple outbreaks. Antifungal resistance is an epidemiologic area of concern and increased antifungal use may be a contributor, she said.
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Dr. Jeniel Nett with C. auris shown on culture plates.
Once established, the organism is persistent: “It is found on mattresses, on bedsheets, IV poles, and a lot of reusable equipment,” said Dr. Nett in an interview. “It appears to persist in the environment for weeks – maybe longer.” In addition, “it seems to behave differently than a lot of the Candida species that we see; it readily colonizes the skin” to a much greater extent than does other Candida species, she said. “This allows it to be transmitted readily person to person, particularly in the hospitalized setting.” However, it can also colonize both the urinary and respiratory tracts, she said.
Which patients are susceptible to C. auris candidemia? “Many of these patients have undergone multiple procedures; they may have undergone mechanical ventilation as well as different surgical procedures,” said Dr. Nett. Affected patients often have received many rounds of antibiotic and antifungal treatment as well, she said, and may have an underlying illness like diabetes or malignancy.
Studies of C. auris outbreaks have begun to appear in the literature and give clinicians some perspective on the progression of an outbreak and potential strategies for containment. A prospective cohort study of a large outbreak of C. auris was conducted by Alba Ruiz-Gaitán, MD, and her colleagues at La Fe University and Polytechnic Hospital, Valencia, Spain (Expert Rev Anti Infect Ther. 2019 Apr;17[4]:295-305). The researchers followed 114 patients who were colonized with C. auris or had C. auris candidemia. The patients were compared with 114 case-matched controls within the hospital’s adult surgical and medical intensive care units over an 11-month period during the hospital’s protracted outbreak.