Optimal susceptibility testing conditions for detection of azole resistance in Aspergillus spp.: NCCLS collaborative evaluation. National Committee for Clinical Laboratory Standards.


Journal Article

The most important role of susceptibility testing is to identify potentially resistant isolates for the agent being evaluated. Standard testing guidelines recently have been proposed for antifungal susceptibility testing of filamentous fungi (molds). This collaborative (eight centers) study evaluated further newly proposed guidelines (NCCLS, proposed standard M38-P, 1998) and other testing conditions for antifungal susceptibility testing of Aspergillus spp. to itraconazole and three new triazoles, posaconazole (SCH56592), ravuconazole (BMS-207147), and voriconazole. MICs of itraconazole, posaconazole, ravuconazole, and voriconazole for 15 selected isolates of three species of Aspergillus (A. fumigatus, A. flavus, and A. terreus) with well documented in vitro, clinical, or animal data were determined in each center by using four medium formulations (standard RPMI-1640 [RPMI], RPMI with 2% dextrose, antibiotic medium 3 [M3], and M3 with 2% dextrose) and two criteria of MIC determination (complete [MIC-0s] and prominent [MIC-2s] growth inhibition) at 24, 48, and 72 h. The highest reproducibility (92 to 99%) was seen with the standard RPMI and M3 media. Moreover, the distinction between itraconazole-resistant (MICs of >8 microg/ml for clinically resistant strains) and -susceptible (MICs of 0.03 to 1 microg/ml) isolates, as well as between a voriconazole-resistant laboratory mutant and other isolates (voriconazole MICs of 2 to >8 versus 0.12 to 2 microg/ml), was more consistently evident with the standard RPMI medium and when MIC-0s were determined at 48 h. These results provide further refinement of the testing guidelines for susceptibility testing of Aspergillus spp. and warrant consideration for inclusion in the future NCCLS document M38-A.

Full Text

Cited Authors

  • Espinel-Ingroff, A; Bartlett, M; Chaturvedi, V; Ghannoum, M; Hazen, KC; Pfaller, MA; Rinaldi, M; Walsh, TJ

Published Date

  • June 2001

Published In

Volume / Issue

  • 45 / 6

Start / End Page

  • 1828 - 1835

PubMed ID

  • 11353633

Pubmed Central ID

  • 11353633

Electronic International Standard Serial Number (EISSN)

  • 1098-6596

International Standard Serial Number (ISSN)

  • 0066-4804

Digital Object Identifier (DOI)

  • 10.1128/aac.45.6.1828-1835.2001


  • eng