Vývoj směsných společenstev patogenních kvasinek Candida albicans a Candida guilliermondii

The objective of this thesis was to investigate how cocultures of Candida albicans and Candida guilliermondii change overtime under control conditions and under the influence of fluconazole. These species are opportunistic fungal pathogens but widely differ in their susceptibility to antimycotic of interest - fluconazole. After a brief introduction to special commonalities, the mechanism of pathogenesis, and the treatment of infection, this work explores each organism's growth curves under selected conditions and the process of artificial evolution using the model of passaging of cocultures. Afterwards, these populations of C. albicans and C. guillieromondii were investigated using qPCR and chromogenic media. qPCR analysis revealed that under control conditions, C. albicans (CA) prevails; the possible reason behind this is a 20% shorter generation time, as revealed by the growth curve. In the presence of fluconazole, two trends occurred. One is related to the innate resistance of C. guilliermondii (CG), where CG was dominant by the end of passaging. The second trend led to CA being the dominant one, despite its susceptibility. This is a result of a heightened resistance, where minimal inhibitory concentration 50 (MIC50) increased almost 10-fold, possibly due to mutations. The change in populations...Cílem této práce bylo zjistit, jak se mění kokultury kvasinek Candida albicans a Candida guilliermondii v průběhu času, jednak za kontrolních podmínek a též pod vlivem flukonazolu. Tyto druhy jsou oportunní fungální patogeny, které se značně liší ve své citlivosti k nejčastěji používanému antimykotiku - flukonazolu. Po krátkém úvodu do společných rysů studovaných druhů, jejich mechanizmu patogeneze a léčby infekcí, které způsobují, se tato práce věnuje růstovým křivkám obou mikroorganizmů za vybraných podmínek a taktéž procesu umělé evoluce pomocí modelu pasážování kokultur. Poté byly tyto populace C. albicans a C. guillieromondii zkoumány pomocí qPCR a chromogenních médií. qPCR analýza odhalila, že za kontrolních podmínek v kulturách převládá C. albicans (CA). Možným důvodem je 20 % kratší generační doba, jak ukazuje růstová křivka. V přítomnosti flukonazolu bylo možno pozorovat dva trendy. Jeden souvisí s přirozenou rezistencí C. guilliermondii (CG) a vedl k tomu, že CG byla na konci pasážování dominantní. Druhý trend vedl k dominanci CA, přestože tato kvasinka je za normálních okolností k flukonazolu citlivá. Na základě tohoto zjištení byla testovaná minimalní inhibiční koncentrace (MIC50) náhodně vybraných kolonií CA. V experimentu, kde ve 12. pasáži CA převládla, došlo až k 10- násobnému...Department of BiochemistryKatedra biochemiePřírodovědecká fakultaFaculty of Scienc

Evolution of mixed cultures of the pathogenic yeasts Candida albicans and Candida guilliermondii

The objective of this thesis was to investigate how cocultures of Candida albicans and Candida guilliermondii change overtime under control conditions and under the influence of fluconazole. These species are opportunistic fungal pathogens but widely differ in their susceptibility to antimycotic of interest - fluconazole. After a brief introduction to special commonalities, the mechanism of pathogenesis, and the treatment of infection, this work explores each organism's growth curves under selected conditions and the process of artificial evolution using the model of passaging of cocultures. Afterwards, these populations of C. albicans and C. guillieromondii were investigated using qPCR and chromogenic media. qPCR analysis revealed that under control conditions, C. albicans (CA) prevails; the possible reason behind this is a 20% shorter generation time, as revealed by the growth curve. In the presence of fluconazole, two trends occurred. One is related to the innate resistance of C. guilliermondii (CG), where CG was dominant by the end of passaging. The second trend led to CA being the dominant one, despite its susceptibility. This is a result of a heightened resistance, where minimal inhibitory concentration 50 (MIC50) increased almost 10-fold, possibly due to mutations. The change in populations..