Colorimetric method for susceptibility testing of voriconazole and other triazoles against Candida species Kolorimetrische Methode zur Empfindlichkeitsprüfung von Voriconazol und anderen Triazolen für Candida-Arten

A microdilution assay using Alamar Introduction Blue, a colorimetric indicator, was compared with the NCCLS macrodilution broth assay for voriVoriconazole is a new triazole agent that appears to have a broader spectrum of antifungal activity conazole, fluconazole, and itraconazole against Candida albicans, Candida glabrata, and Candida krusei. than the parent compound, fluconazole [1–6]. Prior studies that have assessed the in vitro activity Concordance (±2 dilutions) between the two methods was highest for voriconazole (98.3%), of voriconazole against Candida species have utilized the National Committee for Clinical and for fluconazole and itraconazole it was 94.3 and 95.4%, respectively. Twenty-six of 32 (81.2%) Laboratory Standards (NCCLS) recommended microdilution or macrodilution methods. Howdiscordant readings (≥3 dilutions different) were noted in C. glabrata isolates, and all but two ever, the visual turbidity endpoints of these assays are frequently difficult to define for azole agents. isolates showing discordance had higher minimum inhibitory concentration readings with the coloriSeveral species, most notably Candida albicans, exhibit a trailing phenomenon rather than a sharp metric method. end-point [7, 8]. Alamar Blue (AccuMed, Westlake, OH, USA) Zusammenfassung. Ein Mikrodilutionstest unter Verwendung des Farbindikators Alamarblau is an oxidation–reduction colorimetric indicator that, in the presence of actively growing organisms, wurde mit dem NCCLS-Makrodilutionstest zur Empfindlichkeitsprüfung von Candida albicans, C. changes colour from a deep blue to a bright pink. We and others have previously shown the glabrata und C. krusei für Voriconazol, Fluconazol und Itraconazol verglichen. Die Übereinstimmung feasibility of using this system for antifungal susceptibility testing [9–14]. Voriconazole has not pre(±2 Verdünnungsstufen) war am besten bei Voriconazol (98.3%), gefolgt von Fluconazol (94.3%) viously been tested with this method. In this study, we compared the results obtained und Itraconazol (95.4%). Diskordante Ablesungen (≥3 Verdünnungsstufen) traten 26 mal (81.2%) using a colorimetric microdilution method with the NCCLS macrodilution method for isolates bei C. glabrata-Isolaten auf, aber außer zwei zeigten alle diskordanten Isolate höhere MHK-Werte mit of C. albicans, Candida glabrata and Candida krusei against voriconazole, as well as fluconazole and der kolorimetrischen Methode. itraconazole.