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On Wednesday 2 December 2020, Mansoureh Vatanshenassan will defend her PhD thesis

Date 2 December 2020 13:00

### New methods for the rapid identification and antifungal susceptibility testing of clinically important Candida species

The most important achievement of this thesis is the optimization of MALDI Biotyper antibiotic susceptibility test rapid assay (MBT ASTRA) for Candida species against echinocandins in six hours. This method and the process of optimization is described in chapter 2. MBT ASTRA is the most available rapid method for antibiotic/antifungal susceptibility testing (AST/AFST) and it is now ready to use in research. This method is potential to be automated and it will be introduced to routine clinical laboratories after further optimization and automization. Application of this method has been evaluated against echinocandins for clinically important Candida species, namely C. albicans, C. auris, and C. glabrata derived from agar plate, spiked blood samples, and then directly on the patient’s blood samples. Three published articles relevant to MBT ASTRA are presented in separate chapters.

Identification of C. auris derived from spiked blood samples using the MALDI-TOF MS and up-to-date FDA approved database developed by Bruker Daltonic Company, Bremen, Germany is also explained in this thesis. In addition, MALDI-TOF MS is also able to detect hLF(1-11) peptide. Therefore, chapter 7 describes how MALDI-TOF MS is used to identify few numbers of Candida cells (1000 cells/ml) enriched with hLF(1-11) peptide directly from patients blood samples. This evaluation is a promising approach to obtain the most crucial goal in the clinical laboratory which is to detect Candida cells (1-10 cells/ml) directly from patients blood samples.

MALDI-TOF MS is used to type C. auris isolates belonging to four different clades compared to the IR Biotyper method as one of the biochemical typing methods. IR Biotyper (Bruker Daltonics GmbH) has been recently innovated to identify and detect microbial outbreaks in hospitals. So far, the IR Biotyper has not been used for the analysis of human pathogenic Candida yeasts. Since in less than one decade, several C. auris outbreaks have been reported

in various hospitals worldwide, we explored for the first time the applicability of the IR Biotyper for strain typing of C. auris isolates and the results were compared with data obtained using other methods, like microsatellite assay, AFLP, ITS sequencing, and MALDI-TOF MS. The results are summarized in Chapter 6. MALDI-TOF MS has a strong power in the identification and AST/AFST of Candida species, however, it is less accurate for typing Candida isolates. The thesis ends with a discussion chapter (Chapter 8) and a summary (Chapter 9).

### You can follow this PhD Defence Ceremony online

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