Comparison of four commercialized biochemical systems for clinical yeast identification by colour-producing reactions

Abstract

We compared the ability of four commercially available yeast identification systems for routine laboratory hospital use: Auxacolor® (AUX) (Sanofi Diagnostics Pasteur, Marne-la-Coquette), Fungichrom® I (FUC) and Fungifast® ITwin (FUF) (International Microbio, Toulon), Api Candida® (API) (bio Mérieux, Lyon). These systems are based on obtaining a biochemical profile easily defined by colorimetric reactions. We tested 202 yeasts belonging to 19 species which were included or were not included in the manufacturer's data base of the identification systems. Without extra tests, for all the organisms tested, after 24 h of incubation, the percentage of organisms correctly identified was 48% for AUX, 75% for FUC, 77% for FUF and 81% for API. However, if we consider the ratio of the number of correct identifications without extra tests with the number of yeasts included in the manufacturers' data bases (sensitivity) the results increased to 61% for AUX, 81% for FUC, 91% for FUF and 83% for API. These systems are particularly well adapted to medical use, they are simple to set up, interpret, and have very good efficiency for the yeasts most commonly isolated in clinical specimens. The findings reported here indicate that the most favourable results were obtained with FUF and API systems.