Evaluation of Five Phenotypic Tests in the Identification of Candida Species

摘要

Introduction: Rapid and precise identification of Candida species is essential for the proper treatment of Candida infections. Several phenotypic and molecular methods are being used in clinical microbiology laboratories worldwide for the speciation of Candida isolates.Aim: To evaluate the performance of five phenotypic tests in the identification of Candida species.Materials and Methods: Five phenotypic tests (CHROMagar Candida, tetrazolium reduction medium, Candifast, Sugar assimilation and fermentation) were used for the identification of Candida species. Clinical Candida isolates along with reference strains of Candida species were used in the study. The phenotypic test results were compared with PCR-RFLP results to evaluate the performance of the phenotypic tests.Results: All the Candida isolates (100%) were correctly identified to species level by CHROMagar Candida, Tetrazolium reduction medium and Candifast. However, 94.8% and 92.3% of the Candida isolates were identified by sugar fermentation test and assimilation test respectively. The time required to identify the Candida isolates varied with the five phenotypic tests (less than 24 hours for Candifast and maximum of 48-96 hours for sugar assimilation and fermentation).Conclusions: All the five phenotypic tests showed good correlation in the identification of Candida species. However, the time required for identification varied with the different phenotypic tests used, which may have important implications in life threatening infections like candidemia.