Study on virulence factors of Candida tropicalis isolated from clinical samples

Abstract

To determine the in vitro production of virulence factors for Candida (C.) tropicalis, including aspartyl proteinases, phospholipases and hemolytic activities, describe the regulation of virulence factors varying with time in C. tropicalis, and analyze the differences in aspartyl proteinases and hemolytic activities of C. tropicalis isolated from anatomically distinct sites. A total of 64 C. tropicalis strains were spot-inoculated onto bovine albumin agar, egg yolk agar and sheep blood agar plates, respectively. Then the plates were incubated for 24, 48 and 72 hour at 37 °C, respectively. The aspartyl proteinases, phospholipase and hemolytic activities were determined at each time point, respectively. All the C. tropiclais isolates showed positive aspartyl proteinases and hemolytic activities at each time point, but no phospholipases activity was detected in C. tropicalis. On comparison of aspartyl proteinases and hemolytic activities at different time points, aspartyl proteinases activity at 48 and 72 hour was higher than that at 24 hour. During 72 hour, hemolytic activity of C. tropicalis increased. No statistical significant differences in aspartyl proteinases and hemolytic activities of C. tropicalis were observed among different infection sites (P=0.368 and 0.985). The C. tropicalis clinical isolates in China have aspartyl proteinases activity, hemolytic activity, but have no phospholipase activity.