Resumo

In tropical countries Candida tropicalis has been one of the most common Candida causing human diseases. Relatively to C. albicans there are few studies related to virulence factors in this species. This study aimed to evaluate the effect of different growing conditions, related to the presence of blood and its components, in the hemolytic potential and filamentation ability of C. tropicalis isolates and to verify a possible correlation between these two virulence factors in this species. We evaluated the hemolytic and filamentation potential of 5 clinical isolates of C. tropicalis and of the strain ATCC 200956 in cultures in RPMI medium and RPMI supplemented with haemoglobin (1mg.mL^-1), blood (7%), erythrocytes (7%) or plasma (7%) collected from healthy humans. We verify influence of culture condition in the hemolytic and filamentation potential of C. tropicalis. The highest rates of hemolytic activity were promoted by supernatants of cultures supplemented with hemoglobin (7%) and erythrocytes (15.2%), which differed from the remained conditions tested (p<0.05), while hemolysis promoted by supernatants of cultures supplemented with plasma were lower than those found in other conditions (p<0.05). Considering the growing conditions individually, was verified homogeneity among the isolates according to the hemolytic potential in media supplemented with blood, erythrocytes, hemoglobin and plasma. However, in RPMI medium the isolate 236/10 exhibited higher hemolytic activity (p<0.05). The highest rates of filamentation were observed in media supplemented with erythrocytes (7.9%), followed by blood (6.6%) and hemoglobin (5.3%), while the lowest were found for the cultures supplemented with plasma (0.73%). The ability of filamentation of the isolates in cultures supplemented with blood, erythrocytes, hemoglobin and plasma were homogeneous, while in RPMI medium the isolate 207/10 showed higher potential of filamentation. In this study, we showed for the first the occurrence of attenuation of virulence factors in C. tropicalis in the presence of human plasma. Further, under the tested conditions there was no correlation between the secretion of hemolytic factor and filamentation in this specie.