RETROSPECTIVE RE- IDENTIFICATION OF CANDIDA STRAINS BY MALDI-TOF IN SEEK OF CANDIDA AURIS

The yeast C. auris was first described as a new species in 2009. Since then, this species was recognized as an emerging multi-drug-resistant (MDR) yeast that can cause a wide spectrum of infections, ranging from fungemia to deep-seated infections, especially in intensive care settings. It can be not- or misidentified by commercial identification systems. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been considered as a convenient, rapid and accurate technology in the identification of yeast isolates to species level. A total of 132 clinical isolates, collected from 2015 to 2021 in the National Reference Laboratory of Mycology and Sexually Transmitted Infections were included in the study. The isolates were mainly from patients with candidemia and other specimens from invasive Candida infections. The isolates were identified by standard mycological procedures, the assimilation profile was done by commercially available strips and with the automated VITEK2 Compact system. All the strains were identified with MALDI-TOF MS. Antifungal susceptibility testing was conducted to some of the strains by agar disk-diffusion (according to CLSI M44-A2), E-test and VITEK2. Some of the strains which could not be identified or were misidentified by standard mycological procedures were correctly determined by MALDI-TOF MS. None of them was identified as C. auris. There were no large deviations in the antifungal susceptibility profiles of the tested strains. We assess MALDI-TOF MS as convenient, rapid, cost- effective and accurate technology in the identification of fungal strains which are difficult to determine with the traditional procedures. Up to now, isolation of C. auris has not been reported in Bulgaria.