August 28, 2019
A new, multidrug-resistant species of the fungus Candida, named Candida auris (auris meaning ear in Latin), has emerged recently, causing outbreaks in healthcare facilities. It is of considerable concern because of its resistance to antifungal drugs, association with significant mortality, resistance to decolonization in patients, propensity to be misidentified as other Candida species, lack of identification of environmental sources for colonization, and resistance to removal from rooms and equipment used for patient care. C. auris was first identified in 2009 from the ear drainage of a 70-year-old female with ear canal infection in Japan.1 However, the earliest known strain of C. auris dates back to 1996, isolated in a retrospective analysis of previously misdiagnosed samples from Korea.2
In 2011, 3 cases of persistent fungemia were reported. The organisms had unusual antifungal resistance patterns and were identified as C. auris by molecular techniques. Of the 3 patients (two 1-year-old infants and one 74-year-old), 2 succumbed to the infection.2 In February 2015, the U.S. Centers for Disease Control and Prevention (CDC) received 22 fungal isolates with unusual antifungal resistance patterns obtained from an outbreak in Pakistan. None of these 22 isolates could be speciated with commercial diagnostic kits, and they were identified as C. auris by DNA sequencing.3 Soon after the Pakistan outbreak, another outbreak occurred in a hospital in the United Kingdom: 9 patients had bloodstream infections, and more than 40 patients were colonized with C. auris.4 Since then, C. auris has been reported in more than 30 countries, with a significant number of cases detected in the United States.5 The extent to which climate change and other environmental factors may be playing in the evolution of this organism awaits further determination.6
The yeast can persist uncharacteristically on surfaces in healthcare environments, facilitating the spread of the organism between patients.7,8 Clinical isolates of C. auris have been recovered from a variety of specimen types, including normally sterile body fluids, wounds, mucocutaneous surfaces, and skin.7 However, bloodstream infection remains the most commonly observed clinical manifestation of C. auris, with alarming in-hospital global crude mortality rates of 30–60%.9,10 The attributable mortality rates await definition. Due to easy transmissibility in hospital settings, misidentification of the Candida species, multidrug resistance, and high crude mortality rate,10 ,11 C. auris is currently a major global health concern and has received high-profile publicity in the lay literature.
COLONIZATION, SPREAD, AND PREVENTION IN HEALTHCARE SETTINGS
Unlike most pathogenic fungi, the unique ability of C. auris to persist outside the host enables it to spread widely throughout hospital settings. Additionally, C. auris can form highly drug-resistant biofilms on polymeric surfaces such as indwelling catheters and other invasive medical devices.8,12,13 The ...