Uses and Limitations of the XTT Assay in Studies of <i>Candida</i> Growth and Metabolism

Abstract

Colorimetric tetrazolium assays are used increasingly in studies of fungi, often in the absence of standardization or correlation with other methods. We examined species- and strain-related tetrazolium metabolism in Candida albicans and Candida parapsilosis by using XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide] and WST-8 [2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulphonyl)-2H-tetrazolium] and found marked variations. Also, significant signal was often missed in the absence of dimethyl sulfoxide extraction.