Identification of Drug Resistant Candida auris

Abstract

Candida auris is a multidrug resistant yeast, recognized as a cause of invasive infections and health care associated outbreaks around the world. C. auris is of great public health concern, due to its propensity for drug resistance, mode and pace of its transmission, and the possibility that biologic and epidemiologic factors could exacerbate worldwide emergence of C. auris infections. Currently, outbreak response is complicated by limited treatment options and inadequate disinfection strategies, as well as by issues (misidentification, long turnaround time) associated with application of commonly used diagnostic tools. Misdiagnosis of C. auris is common since many diagnostic platforms available in clinical and public health laboratories depend on reference databases that have not fully incorporated C. auris . Moreover, the correlation between minimal inhibitory concentration values (MICs) and clinical outcomes is poorly understood resulting in the absence of C. auris -specific breakpoints. New, accurate and fast diagnostic methods have emerged to facilitate effective patient management and improve infection control measures, ultimately reducing the potential for C. auris transmission. This review provides an overview of available C. auris detection/identification and antifungal susceptibility determination methods and discusses their advantages and limitations. A special emphasis has been placed on culture-independent methods that have recently been developed and offer faster turnaround times.

Fungal diseases as neglected pathogens: A wake-up call to public health officials

“…Late laboratory diagnosis of cases of necrotizing mucormycosis caused by Apophysomyces trapeziformis resulted in 5 deaths in Missouri in 2011 [44]. Addressing the epidemic of C. auris has also been impeded by inherent deficiencies with classical laboratory methods utilized by many clinical laboratories as well as public health institutions [39]. These cases reinforce the notion that tests rapidly identifying infecting fungi have the potential to impact the course of fungal diseases beneficially.…”

“…Difficulties are nevertheless present as fungi typically reproduce slowly, and culture methods may take as long as a month to identify common species such as Histoplasma sp. Moreover, susceptibility testing to guide clinicians is also problematic, and breakpoints are not available for several important human pathogenic fungi, including C. auris [39]. Moreover, as reviewed by Wickes and Wiederhold [23], detection of less frequently encountered fungi is considerably more complex because routine clinical laboratories may lack the expertise and appropriate equipment to identify pathogenic agents.…”

External Quality Assessment Evaluating the Ability of Dutch Clinical Microbiological Laboratories to Identify Candida auris

“…However, these methods are still used by a significant number of laboratories elsewhere in the world. The misidentifications by other methods have been extensively reviewed elsewhere [25,41].…”

“…They are potentially of use in an outbreak situation, as most are sensitive enough to be used on direct material and do not require a culture, in contrast to MALDI-TOF MS. The published papers that have evaluated the molecular methods to detect and identify C. auris have been reviewed elsewhere [25,48].…”

“…The lack of its early correct identification, and the failure to implement the immediate contact precautions of infected or colonized patients, are the key conditions in need of consideration to prevent hospital transmissions and silent outbreaks. Reliable identification of C. auris is possible by sequence analysis of the D1/D2 region of the large subunit and the internal transcribed region of the ribosomal RNA, or by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) [22][23][24][25][26]. However, there is a risk of misidentification when biochemical assays are used, or when the reference libraries lack C. auris spectra in their databases when MALDI-TOF MS systems are used.…”