In vitro susceptibility of the yeast pathogen cryptococcus to fluconazole and other azoles varies with molecular genotype

J Clin Microbiol. 2010 Nov;48(11):4115-20. doi: 10.1128/JCM.01271-10. Epub 2010 Sep 15.

Abstract

Cryptococcosis is primarily caused by Cryptococcus neoformans and Cryptococcus gattii. These two pathogenic species each divide into four distinct molecular genotypes. In this study, we examined whether genotype influenced susceptibility to antifungal drugs used to treat cryptococcosis using the broth microdilution method described by the Clinical and Laboratory Standards Institute. C. gattii isolates belonging to molecular genotype VGII had significantly higher MIC values for flucytosine and all azole antifungal agents tested, particularly fluconazole, than isolates of other C. gattii genotypes. In an extended analysis of fluconazole susceptibility, VGII isolates from the north and west of Australia required higher drug levels for inhibition than those from Vancouver Island, Canada. Within C. neoformans, genotype VNII had significantly lower geometric mean MICs for fluconazole than genotype VNI. These results indicate that cryptococcal species, molecular genotype, and region of origin may be important when deciding treatment options for cryptococcosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antifungal Agents / pharmacology*
  • Australia
  • Azoles / pharmacology*
  • Canada
  • Cryptococcosis / microbiology
  • Cryptococcus gattii / classification
  • Cryptococcus gattii / drug effects*
  • Cryptococcus gattii / genetics
  • Cryptococcus gattii / isolation & purification
  • Cryptococcus neoformans / classification
  • Cryptococcus neoformans / drug effects*
  • Cryptococcus neoformans / genetics
  • Cryptococcus neoformans / isolation & purification
  • Fluconazole / pharmacology*
  • Genotype
  • Humans
  • Microbial Sensitivity Tests

Substances

  • Antifungal Agents
  • Azoles
  • Fluconazole