Comparative performance of Fungichrom I, Candifast and API 20C Aux systems in the identification of clinically significant yeasts.

Abstract

To compare the performance of current chromogenic yeast identification methods, three commercial systems (API 20C Aux, Fungichrom I and Candifast) were evaluated in parallel, along with conventional tests to identify yeasts commonly isolated in this clinical microbiology laboratory. In all, 116 clinical isolates, (68 Candida albicans, 12 C. parapsilosis, 12 C. glabrata and 24 other yeasts) were tested. Germ-tube production, microscopical morphology and other conventional methods were used as standards to definitively identify yeast isolates. The percentage of isolates identified correctly varied between 82.7% and 95.6%. Overall, the performance obtained with Fungichrom I was highest with 95.6% identification (111 of 116 isolates). The performance of API 20C Aux was higher with 87% (101 of 116 isolates) than that of Candifast with 82.7% (96 of 116). The Fungichrom I method was found to be rapid, as 90% of strains were identified after incubation for 24 h at 30 degrees C. Both of the chromogenic yeast identification systems provided a simple, accurate alternative to API 20C Aux and conventional assimilation methods for the rapid identification of most commonly encountered isolates of Candida spp. Fungichrom seemed to be the most appropriate system for use in a clinical microbiology laboratory, due to its good performance with regard to sensitivity, ease of use and reading, rapidity and the cost per test.