orthopsilosis and 4 C. metapsilosis strains. Discussion Candida parapsilosis accounts for a significant proportion of nosocomial infections, with an increasing prevalence in hospital settings. As with other Candida

species, invasion of C. parapsilosis can result in severe disease, particularly in hosts with a compromised immune system. Unlike C. albicans, the transmission and acquisition of infection due to C. parapsilosis is mainly exogenous and environmental strains are often the source of infection. The main issue of this study was, therefore, the comparison of the virulence potential of environmental and clinical C. parapsilosis isolates. Macrophages play an important role in the immune response, buy EPZ015938 directly by phagocytosing and killing microbial pathogens, and indirectly by processing and presenting Nutlin-3a cell line antigens and secreting cytokines [22]. Although there were variations in the intracellular killing of the different strains, the average percentage was of about 35% for the clinical isolates,

in agreement with the results obtained by Gácser et al. [18] for C. parapsilosis. Curiously, these values were much lower for the environmental strains, pointing to a clear difference between environmental and clinical isolates, regarding interaction with macrophages. A great variability in the capacity of the strains to cause cell damage was also found, and again environmental isolates induced significantly higher macrophage damage than blood isolates, confirming a strong relationship between the source of the isolates and their ability to cause damage. It was also observed that C. orthopsilosis induced a high level of macrophage damage, similar to C. parapsilosis bloodstream isolates, while C. metapsilosis induced the lowest cytotoxicity level. These facts agree with previous works on reconstituted human oral epithelial Ergoloid and epidermal tissues [19] and microglial cells [23], showing that C. metapsilosis was less virulent compared to C. orthopsilosis and C. parapsilosis. To correlate these findings with the morphology, yeast strains were induced to filament

in the presence of serum and results showed that 57.7% of the tested C. parapsilosis isolates were able to produce pseudo-hyphae after 12 hours of incubation, with the clinical isolates filamenting in a higher percentage than the environmental strains. Curiously, this high Wortmannin filamentation ability was not correlated with higher macrophage cytotoxicity as it has been described for C. albicans [24, 25]. In our study, although C. parapsilosis filamentation occurred right after 4 hours, differences in macrophage death were observed only after 12 hours of co-incubation. Incubation with the strains that did not develop pseudo-hyphae revealed that, after 12 hours of infection, a huge number of macrophages had disappeared and the yeast number was high.