In view of the increase of healthcare-associated Candida auris outbreaks in the Region of the Americas and in the context of the COVID-19 pandemic, the Pan American Health Organization/World Health Organization (PAHO/WHO) recommends that Member States build capacity for early detection and effective reporting, with the goal of implementing public health measures to prevent and control its spread in health services.
Since it was first isolated in 2009, in the external ear canal of a Japanese patient, the yeast Candida auris (C. auris) has been identified as a colonizing organism and cause of infection in humans in healthcare services in several countries around the world. In most reported cases, isolates were obtained from blood cultures or cultures from deep anatomical sites. Invasive medical devices, mechanical ventilation, extended stay in intensive care units, and prior exposure to broad-spectrum antibiotics were risk factors associated with these infections.
Candida auris poses a public health problem, because, unlike the other species of the genus Candida, it is difficult to identify, is multi-drug-resistant to antifungals (see Box 1 for further details) and can persist in the hospital environment and spread easily among patients. These characteristics are responsible for high mortality and underscore the importance of constant clinical and microbiological suspicion, for early detection and immediate infection prevention and control measures. This requires health workers to keep their knowledge fully up to date and ensure fluid communication among the different health workers involved.
Whole genome sequencing suggests that C. auris arose simultaneously and independently in four regions of the world. Through phylogenetic analysis, isolates were grouped geographically into four main clades: clade I (Southern Asia), clade II (Eastern Asia), clade III (Africa), and clade IV (South America). A single isolate belonging to a potential clade V has been identified in Iran. It is now known that there is phylogeographic mixing of the clades, with the exception of clade IV, which presents a more defined phylogeographic substructure, with isolates mainly from South America.
Commercial methods available in standard clinical laboratories incorrectly identify C. auris, primarily as C. haemulonii, C. famata, C. kefyr, C. duabushaemulonii, C. pseudohaemulonii, among others. Consequently, the incidence or prevalence of infections caused by this yeast may be underestimated and its management could be inappropriate. It is important to point out that the most widely used conventional methods and automated devices in the Region of the Americas have shown limited capacity to correctly identify C. auris. However, the general performance of one of the automated devices with its up-to-date database seems to differ according to genetic clade, with South American isolates (clade IV) yielding the most accurate results.
Protein analysis, using MALDI-TOF, with its up-to-date database, as well as molecular biology techniques (PCR) have shown to be the most reliable methods for correctly identifying this microorganism.