Comparison of disk diffusion, E-test and broth microdilution test in determination of susceptibility of Aspergillus species to amphotericin B, itraconazole and voriconazole

J Chemother. 2008 Feb;20(1):87-92. doi: 10.1179/joc.2008.20.1.87.

Abstract

In response to the recent increase in Aspergillus infections, new antifungal agents have become available accompanied by studies on antifungal susceptibility tests for epidemiological follow-up. The aim of this study was to compare the efficacy of Clinical Laboratory Standards Institute (CLSI) M 38-A broth microdilution test with the disk diffusion and E-test in determining the susceptibility of Aspergillus spp. to amphotericin B, itraconazole and voriconazole. The study was carried out on 18 A. fumigatus, 7 A. flavus, 5 A. niger and 2 A. versicolor strains isolated from clinical samples. The microdilution method was performed by following the instructions of CLSI M 38-A. The E-test and disk diffusion tests were performed according to the instructions of their manufacturers. The percent agreement between the E-test and CLSI M38-A broth microdilution test at 24 (48) h within +/- 2 dilutions was, respectively, 81% (69%) for amphotericin B, 75% (72%) for itraconazole and 85% (81%) for voriconazole. The disk diffusion test showed good correlation with the E-test but poor correlation with the broth microdilution test for the three antifungal agents we tested. In conclusion, E-test and disk diffusion test have their advantages such as ease of application and interpretation, but their correlation with the broth microdilution should be improved.

Publication types

  • Comparative Study

MeSH terms

  • Amphotericin B / pharmacology*
  • Antifungal Agents / pharmacology*
  • Aspergillus / drug effects*
  • Aspergillus / isolation & purification
  • Disk Diffusion Antimicrobial Tests
  • Humans
  • Itraconazole / pharmacology*
  • Microbial Sensitivity Tests*
  • Pyrimidines / pharmacology*
  • Triazoles / pharmacology*
  • Voriconazole

Substances

  • Antifungal Agents
  • Pyrimidines
  • Triazoles
  • Itraconazole
  • Amphotericin B
  • Voriconazole