The use of readily available laboratory tests for the identification of the emerging yeast Candida auris in Mexico

Identification of the emerging multidrug-resistant yeast Candida auris is challenging. Here, we describe the role of the Mexico national reference laboratory Instituto de Diagnóstico y Referencia Epidemiológicos Dr. Manuel Martínez Báez (InDRE) and the Mexican national laboratory network in the identification of C. auris. Reference identification of six suspected isolates was done based on phenotypic and molecular laboratory methods, including growth in special media, evaluation of isolate micromorphology, and species-specific PCR and pan-fungal PCR and sequencing. The four C. auris isolates identified were able to grow on modified Sabouraud agar with 10% NaCl incubated at 42 °C. With one exception, isolates of C. auris were spherical to ovoid yeast-like cells and blastoconidia, with no hyphae or pseudohyphae on cornmeal agar. C. auris isolates were resistant to fluconazole. Species-specific and pan-fungal PCR confirmed isolates as C. auris. Sequence analysis revealed the presence of two different C. auris clades in Mexico, clade I (South Asia) and clade IV (South America).