Antifungal Susceptibility Testing and Cluster Analysis of Candida auris Strains

Candida auris is an opportunistic pathogen that has become widespread in recent years and shows resistance to multiple drugs. The aim of our study was to determine the antifungal susceptibilities of C. auris isolates, to perform a dendrogram from the mass spectra of strains obtained from matrix-assisted laser desorption ionization-time of flight mass spectrometry in order to evaluate the proteomic similarities of the strains and determine the geographical clade of C. auris strains in this study by the help of Multiplex RT-PCR.

The samples yielded 58 C. auris isolates. MALDI TOF MS (BioMerieux, France) was used for identification of the isolates and Sensititre Yeast One (Thermoscientific) system was used for antifungal susceptibility testing. Dendrograms of strain's spectra were generated by using the RUO/Saramis (BioMerieux, France) database and evaluated through hierarchical clustering analysis. The selected nine strains were examined at the clade level by using Multiplex RT-PCR. Results The susceptibility profile of the strains revealed resistance to Fluconazole in 84% (MICs ≥ 32) and resistance to Amphotericin B in 60% (MIC ≥ 2). All strains were found to be sensitive to Anidulafungin and Micafungin. The dendrogram of the main spectra of C. auris isolates showed a similarity range of 35 - 100%. The nine strains studied were identified as clade 1 (South Asian).

It was determined that C. auris strains were members of geographical clade 1, and the Amphotericin B resistance was found to be higher than expected. This situation poses a threat to critically ill patients.