Discrimination of Clinical and Food-Derived <em>Candida</em> Strains Using Biotyping and Molecular Typing Approaches

Identification and differentiation of Candida spp. yeasts, especially clinically relevant isolates, is of high importance with respect to their origin, pathogenic potential, colonization pattern, and resistance to antimycotics. Currently, numerous typing methods with varying or unknown discriminatory power are used. The aim of this study was to evaluate the usefulness of five methods—biotyping using the API system, ITS1 and ITS4 sequence analysis, polymorphism of ITS1 and ITS4 regions, multiplex PCR of ITS1, ITS3, and ITS4 regions, and karyotyping—for typing strains differing in origin (24 clinical and 18 food-borne strains). The highest discriminatory power was obtained for ITS region sequencing and karyotyping, both yielding a discrimination index of 1.000. For the other methods, the discrimination index ranged from 0.957 for genotyping based on ITS region polymorphism to 0.997 for multiplex PCR-genotyping. Although biotyping demonstrated relatively high discriminatory potential, its application in yeast identification led to misclassification of 66.7% of isolates when compared to ITS region sequencing results. Due to the varying usefulness of different typing methods, determining the discrimination index appears to be highly valuable. Moreover, application of a method with a discrimination index of 1.000 in yeast typing is crucial for correct interpretation of results concerning strains origin and similarity.