Molecular Discrimination of the Candida parapsilosis Species Complex via SADH Gene Analysis and Evaluation of Proteinase Activity Among the Isolates

Abstract

Background: Candida parapsilosis consists of three species of C. parapsilosis sensu stricto, C. metapsilosis, and C. orthopsilosis. Proteinase activity is considered as one of the major virulence factors in the pathogenicity of Candida species. Objectives: We aimed to discriminate clinical isolates of the C. parapsilosis species complex through analysis of the secondary alcohol dehydrogenase (SADH) gene using BanI restriction enzyme and evaluation of proteinase activity among the isolates. Methods: In this study, 71 clinical isolates identified as C. parapsilosis were included. The species were discriminated via analysis of SADH gene using S1F and S1R primers. The polymerase chain reaction (PCR) products were digested with restriction enzyme BanI. Proteinase activity of the species was evaluated using bovine serum albumin agar medium. To analyze the data, Fisher's exact test was used. Results: The results presented that out of the 71 species tested, 65 (91.5%) were C. parapsilosis sensu stricto, 6 (8%) were C. orthopsilosis, and no species were C. metapsilosis. Proteinase activity was observed in 70.1% and 80.3% of C. parapsilosis and C. orthopsilosis species, respectively. Conclusions: In this study, the most dominant species identified by the molecular method was C. parapsilosis sensu stricto. The high rate of proteinase activity among the isolates indicates the importance of this enzyme as a virulence factor in the pathogenicity of this complex.