RESUMO
BACKGROUND: It has been observed an spectacular increasing of opportunistic Candida yeast infections. Many of them are fatal, and rapid and effective identification of the infecting species contributes to start the correct treatment. Several new methods for yeast identification have become available; Microring YT is one of these methods based on the growth inhibition by 6 different chemical products. The aim of this work is to study the performance of the test using representative clinical yeast isolates. METHODS: A total of 146 strains belonging to the 5 most common Candida species isolated in the clinical laboratory were identified using conventional methods (germ tube and chlamydospores production, and the standard API 20C AUX and 16 sugars auxonography; Institute Pasteur) and the Microring YT System. This test uses the differing susceptibilities of yeast to 6 discs mounted on a filter paper ring. The chemical products and dyes are: janus green, ethidium bromide, triphenyl tetrazolium chloride, brilliant green, cycloheximide and rhodamine 6G. The inhibition pattern of a 6 digit code is compared with a list of profiles. RESULTS: Using the Microring YT system 112 of the 146 studied strains were correctly identified with an overall concordance of 77% between this method and the standard one. The morphological study (germ tube production) increased 6% the identification of Candida albicans. Better results were obtained with C. krusei and C. parapsilosis (85% of concordance). With C. glabrata only 59% of concordance was found. CONCLUSIONS: In spite Microring YT is a simple method, easy to perform and read, it was considered inadequate for the identification of Candida species as a routine microbiological procedure.