Evaluation of the NCCLS M27-2A, Sensititre YeastOne, disk diffusion, and Etest methods for determining susceptibilities of Candida dubliniensis to Voriconazole, Fluconazole and Itraconazole

M.P. Arévalo,1 F.J. Salgado,1,2 J. Alcoba,1,2 A. Arias,1 M.D. Moragues3 and G. Quindos3

Author address: 

1Universidad de La Laguna, Facultad de Medicina, Medicina Preventiva y Salud Pública, La Laguna. Tenerife, Spain, 2Hospital Universitario de Ntra. Sra. de Candelaria, Microbiologia, Santa Cruz de Tenerife, Spain and 3Universidad del Paí­s Vasco. Fac


Objectives: Candida dubliniensis is a recently (1995) described Candida species closely related to Candida albicans, which has been primarily associated with oral candidiasis in HIV-infected patients but has also been recovered from a wide range of anatomical sites and clinical samples. C. dubliniensis is prevalent throughout the world. The great majority of Candida dubliniensis isolates are susceptible to all of the commonly used antifungal agents; however, reduced susceptibility to azole drugs has been reported in clinical isolates. The purpose of this study was to compare the in vitro activity of Voriconazole, Fluconazole, and Itraconazole, against 62 isolates of Candida dubliniensis by the NCCLS M27-2A (BMD), Sensititre YeastOne, disk diffusion and Etest methods and to study the effect of the time of reading (24 h vs. 48 h) in the susceptibility testing. Results: All of isolates were susceptible for the Voriconazole by the Sensititre, Etest, and disk diffusion methods, three isolates were considered resistant by the reference BMD method at 48 h (agreement 95.1%) while at 24 h only one isolate was resistant (agreement 98.4%). Concerning Fluconazole, all the isolates were susceptible by the Sensititre and Etest methods and only one showed dosedependent susceptibility by disk diffusion method. By the reference BMD method at 48 h, there were one isolate S-DD and three resistant (agreement 93.5%). At 24 h none of the isolates was S-DD and only one was resistant (agreement 98.4%). For Itraconazole, all the isolates were susceptible by Etest method, although two isolates showed dosedependent susceptibility by Sensititre (agreement 96.8%), ten by reference BMD method at 48 h (agreement 82.2%) and three at 24 h (agreement 95.2%). Only one isolate was resistant at 48 h by the reference BMD method. The highest rate of strains with decreased susceptibility was obtained against Itraconazole as it has been previously described by other authors. The lowest MICs were observed for Voriconazole and these results suggested that the in vitro potency of Voriconazole is greater than that of the rest of azoles tested, which is concordant with the results that have been reported by other investigators. Conclusions: The MICs results obtained by all the methods demonstrated that C. dubliniensis is very susceptible to all the antifungal agents tested. Voriconazole was the most potent in vitro followed by Fluconazole, and Itraconazole. The highest rate of resistance was obtained against Itraconazole with a high number of isolates defined as susceptible dose-dependent. The agreement between the MICs registered at 24 and 48 h by the reference BMD was better for Voriconazole.

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Full conference title: 

2nd Trends in Medical Mycology
    • TIMM 2nd (2010)