Due to the aging population and increasing number of immunocompromised individuals, fungal infections are on the rise. Yeasts of the genus Candida are the most common causative agents, with growing resistance linked to frequent antifungal use. As extreme environments may serve as reservoirs of potentially pathogenic fungi, this thesis investigated the resistance of five Candida species, isolated from glacial water, brine, and urban areas, against nine antifungal agents. Minimum inhibitory concentration (MIC) was determined using a commercial Thermo Scientific plate. Yeasts were applied in concentration of 1.5 × 10⁸ CFU/mL. Growth was assessed visually: blue colour indicated no growth, pink indicated good growth, and the MIC was the first well with different colour than the positive control. Echinocandins, amphotericin B, and flucytosine were effective against most strains. The highest resistance was found in Candida tropicalis, with all strains resistant to at least one agent. These strains originated from urban environment, which raises concern as C. tropicalis is increasingly present in infections. For Candida parapsilosis, we additionally explored the relationship between colony phenotype and resistance. Notably, the Dead Sea strain exhibited a unique concentric phenotype and high resistance to fluconazole. Our findings highlight the potential threat posed by environmental Candida strains.
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