Comparison of rapid methods using fluorogenic-chromogenic assays for detecting Candida albicans

Abstract

Three hundred and forty clinical isolates of Candida species and Saccharomyces cerevisiae were tested in order to evaluate different methods for identification of Candida albicans using fluorogenic or chromogenic substrates. Detection of N-acetyl-β-D-galactosaminidase (NAGase) was performed with ready-to-use agars such as Fluoroplate Candida Agar (Merck, Germany), MUAG Candida Agar and MUAG Sabouraud Agar (Biolife, Italy) which contained 4-methylumbelliferyl-N-acetyl-β-D-galactosaminide (4-MUAG). MUAG Candi Kit and RAP-ID-ALBICANS (Biolife, Italy) and Albicans ID Agar (bioMerieux, France) were also used. The Vitek AMS System was used as a reference identification method for all isolates. NAGase activity could be detected for C albicans with Fluoroplate Candida Agar (98.8%), MUAG Sabouraud Agar (98.4%), Albicans ID (99.6%). MUAG Candi Kit (97.5%) and RAP-ID-ALBICANS (96.2%). Proline aminopeptidase examined with RAP-ID-ALBICANS was present in 98.7% of C. albicans. There was one false-positive result for C. tropicalis (9.1%) on Fluoroplate Candida Agar, one false-positive result for C. glabrata (2.2%) on Albicans ID Agar: five false-negative results for C. albicans (3.1%), but no false-positive results for the other tested species were observed with RAP-ID-ALBICANS.