Biological Features, Antimicrobial Susceptibility and Phenotypic Characterization of CDC B11903 Grown at Different Temperatures.

Thermo-tolerance is a virulence factor responsible for the emergence of new fungal pathogens, including (formerly classified as , ). It has been shown that in the thermo-tolerance, as well as other virulence traits, such as the ability to aggregate, to form pseudo-hyphae, or to produce melanin are strain-specific features. Here, we investigated the impact of different temperatures (25 °C, 37 °C and 42 °C) on the phenotypic and virulence profile of strain CDC B11903. The results show a positive correlation between the resistance to antifungals and increasing temperature from 25 °C to 37 °C, while no differences were observed between 37 °C and 42 °C, except for Anidulafungin. Furthermore, growth was impaired at 25 °C as compared to 37 °C and 42 °C. Except for the haemolytic activity, which increased with rising temperatures, phospholipase, lipase and biofilm production were found at all tested temperatures. Moreover, the ability to produce melanin was observed only at 37 °C and 42 °C. The capacity to grow as pseudo-hyphae or in clusters and to adhere to both biotic and abiotic surfaces were observed at all the temperatures tested, with increased propensity of to adhere to abiotic surfaces with rising temperatures. The results underline the thermo-tolerance of strain B11903 and its increased virulence profile at human body temperature both in physiological (37 °C) and febrile state (42 °C).