Most cases of fungal bloodstream infections (BIs) are attributed to Candida albicans; however, non-Candida albicans Candida species have recently been identified as common pathogens. Although hemolytic factor is known to be putative virulence factor contributing to pathogenicity in Candida species, its production is poorly evaluated. The present study was undertaken to analyze the production of hemolytic factor by C. albicans (10), C. tropicalis (13), and C. parapsilosis (8) isolates associated with BIs. Data of hemolysis zones on plate assay revealed that the majority of C. albicans isolates produced mild hemolytic activity whereas the majority of C. tropicalis produced strong activity. None of the tested C. parapsilosis isolates exhibited hemolysis on plate assay. We also evaluated the hemolytic activity in the cell-free broth. There were no significant differences (P > 0.05) in the secreted hemolytic activity among intra-species isolates. Different levels of secreted hemolytic factor were observed for Candida species, where C. tropicalis exhibited the highest production of hemolytic factor (P < 0.05) followed by C. albicans and C. parapsilosis. Inhibition of hemolysis (up to 89.12 %) from culture supernatant, following incubation with the lectin Concanavalin A (Con A), was observed for all three Candida species. This finding suggests that the secreted hemolytic factor of C. tropicalis and C. parapsilosis may be a mannoprotein, similar to that described for C. albicans.

Hemolytic factor production by pathogenic Candida species is considered an important attribute in promoting survival within the mammal host through the ability to assimilate iron from the hemoglobin-heme group. Hemolytic capability has been evaluated for Candida species based on hemolysis zones on plate assay, analysis of hemolytic activity in liquid culture medium, and hemolysis from cell-free culture broth. The production of hemolytic factor is variable among Candida species, where C. parapsilosis is the less hemolytic species. In general, no intraspecies differences in beta-hemolytic activities are found among isolates belonging to C. albicans, C. glabrata, C. krusei, C. tropicalis, and C. parapsilosis. The production of hemolytic factor by Candida species is affected by several factors such as glucose supplementation in the culture medium, blood source, presence of erythrocytes and hemoglobin, and presence of electrolytes. On the basis of existing achievements, more researches are still needed in order to extend our knowledge about the biochemical nature of hemolytic molecules produced by distinct Candida species, the mechanism of hemolysis, and the molecular basis of the hemolytic factor expression.