Background: The Clinical Laboratory Standards Institute (CLSI) M38-A is the reference method for testing azoles against filamentous fungi, but agar-based methods may provide simple and reliable alternatives. Validation of these methods against the CLSI M38-A method is needed before they are adopted for testing newer antifungal agents such as POS. Methods: We performed in-parallel testing of DD (5 μg POS disk (Becton Dickinson), CLSI M44-A method), Etest (AB Biodisk) and BMD (CLSI M38-A method) AFST of POS against 146 clinical isolates of filamentous fungi collected from 2000-2005. The isolates included 68 Aspergillus fumigatus, 45 A. flavus, 15 A. niger, 9 A. terreus, 3 A. niveus, 2 A. nidulans, 2 Mucor spp. and 4 Rhizopus spp. POS activity was determined by DD using Mueller Hinton with 2% glucose and methylene blue (0.5 μg/ml), by Etest using RPMI agar buffered with MOPS and 2% glucose, and then compared to its activity by the BMD method. For comparison purposes only, the POS breakpoints used were the same as those recently approved for voriconazole; BMD and Etest, Susceptible (S): = 4 μg/ml; and for DD, S: >= 17 mm; SDD: 14-16 mm; R: = 4 μg/ml) by the BMD method. Conclusions: DD and Etest agar-based methods for testing POS correlated well with the M38-A method. These methods represent reliable alternatives for AFST of POS against the filamentous fungi.
Full conference title:
46th Interscience Conference on Antimicrobial Agents and Chemotherapy
- ICAAC 46th