A comparative study of the disc diffusion method with the broth microdilution and Etest methods for voriconazole susceptibility testing of Aspergillus spp.

OBJECTIVE The activity of voriconazole against Aspergillus spp. (n = 77) was tested by the Etest, disc diffusion and the NCCLS M38-A methods. METHODS Four Rhizomucor spp. isolates were included to study the suitability of the three susceptibility testing methods to detect isolates resistant to voriconazole. The disc diffusion method performed on Mueller-Hinton agar (Difco) supplemented with 2% glucose and Methylene Blue (0.5 mg/L) gave zone diameters with very clear border edges. RESULTS The disc diffusion method showed excellent correlation with the Etest and the NCCLS methods. CONCLUSION On the basis of our results, it appears that the disc diffusion test is a useful method for testing the activity of voriconazole against Aspergillus spp.