Evaluation of disk diffusion method compared to broth microdilution for antifungal susceptibility testing of 3 echinocandins against Aspergillus spp

Diagn Microbiol Infect Dis. 2012 May;73(1):53-6. doi: 10.1016/j.diagmicrobio.2012.01.006. Epub 2012 Apr 4.

Abstract

We tested the susceptibility of caspofungin, micafungin, and anidulafungin against Aspergillus spp. isolates by the new Clinical and Laboratory Standards Institute M51-A disk diffusion (DD) and the broth microdilution methods. A total of 65 clinical isolates of Aspergillus spp. were evaluated. The DD assay was performed on nonsupplemented Müeller-Hinton agar using caspofungin 2-μg, micafungin 1-μg, and anidulafungin 2-μg disks. Echinocandin minimal effective concentrations (MECs) and inhibition zones (IZs) were read after 24 to 48 (A. terreus) h at 35 °C. Caspofungin MECs for all Aspergillus spp. strains tested were ≤ 0.25 μg/mL; IZs were ≥ 15 mm for most species except for A. terreus (11-22 mm). Both micafungin and anidulafungin MECs were ≤ 0.015 μg/mL, but micafungin IZs were ≥ 14 mm while anidulafungin IZs were ≥ 22 mm. As for caspofungin, the DD method could be a useful method for susceptibility testing of micafungin and anidulafungin against Aspergillus spp.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Antifungal Agents / pharmacology*
  • Aspergillosis / microbiology
  • Aspergillus / drug effects*
  • Aspergillus / isolation & purification
  • Culture Media / chemistry
  • Echinocandins / pharmacology*
  • Humans
  • Microbial Sensitivity Tests / methods

Substances

  • Antifungal Agents
  • Culture Media
  • Echinocandins