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Selected Publication:

Heidrich, K.
Identification and strain typing of Candida albicans isolates from clinical samples.
Humanmedizin; [ Diplomarbeit ] Medical University of Graz; 2014. pp. 88 [OPEN ACCESS]


Authors Med Uni Graz:
Buzina Walter
Krause Robert

Introduction: Invasive fungal infections are live-threatening diseases that occur particularly in immunodeficient and multimorbid patients. The facultative pathogenic yeast Candida albicans colonizes the mucosal surfaces and the skin of healthy individuals. Even though, it constitutes the most important fungal pathogen. The mortality of blood stream infections due to Candida species is about 40%. Therefore, fast detection and proper treatment are crucial for the outcome of those affected. Material and Methods: For this study 181 clinical yeast isolates were classified to species level by means of a mass spectrometric technique (MALDI-TOF MS). Susceptibility testing for 8 antifungal agents was performed with all Candida albicans isolates. A panel of 44 invasive and colonizing isolates was chosen for Multi Locus Sequence Typing (MLST) to investigate the phylogenetic relationships. An echinocandin resistant isolate was analyzed regarding mutations in the FKS1-gene, known as a hotspot for mutations that lead to reduced echinocandin susceptibility. Results: Of 181 isolates, 140 were C. albicans (77%). All isolates were susceptible to the tested antifungals, except for two. An echinocandin resistant isolate showed 2 nucleotide point mutations in FKS1, while a susceptible isolate obtained some weeks prior from the same patient did not show these mutations. In our PCR investigations we found numerous new MLST types. These types predominantly clustered in clades 1, 2 and 3. No statistically relevant differences in the distribution of invasive and colonizing isolates within clonal clusters were found. Discussion: The early detection of echinocandin resistance and the development of alternative treatment strategies are of great clinical importance. Nevertheless, FKS1 mutations are infrequent in Candida albicans. Despite some limitations, MLST is currently seen as the reference method for phylogenetic typing. Our cluster distributions as determined by MLST were similar to previous investigations. Samples from the same patients, obtained from different sites, showed the same MLST profile, suggesting endogenous transmission. Patients most likely acquire candidal infections from their own colonizing flora and thus colonization is a risk factor for disseminated candidiasis in the susceptible host.

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