Related Experiment Video
Updated: Jun 16, 2026
08:45
Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance
Published on: December 28, 2017
Screening for drug-resistant Candida yeasts with chromogenic agar
William R Kirkpatrick1, Joseph D Zimmerman, Fadi P Haikal
1Department of Medicine, South Texas Veterans' Health Care System, San Antonio, TX, USA.
Medical Mycology
|January 30, 2010
Summary
Agar dilution effectively screens yeast for antifungal drug susceptibility, showing high accuracy compared to CLSI methods for echinocandins and azoles. However, accurately determining resistance can be challenging and species-dependent.
Area of Science:
- Medical Mycology
- Antimicrobial Resistance
- Clinical Microbiology
Background:
- Emerging resistance to antifungal drugs necessitates reliable susceptibility testing methods.
- Standard methods for yeast antifungal susceptibility testing can be time-consuming.
- Novel screening approaches are needed for rapid assessment of antifungal drug efficacy.
Purpose of the Study:
- To evaluate the utility of agar dilution using CHROMagar Candida medium for screening yeast susceptibility to echinocandins and azoles.
- To compare the accuracy of this agar dilution method against the Clinical and Laboratory Standards Institute (CLSI) reference method.
- To assess the performance of agar dilution for various Candida species.
Main Methods:
- Agar dilution susceptibility screening was performed by incorporating echinocandins and azoles into CHROMagar Candida medium.
- Susceptibility was assessed based on yeast growth characteristics, specifically decreased colony size in the presence of antifungals.
- The method was validated using clinical Candida isolates including C. albicans, C. glabrata, and C. parapsilosis.
- Results were compared against established CLSI-based minimum inhibitory concentration (MIC) values.
Main Results:
- The agar dilution method demonstrated high accuracy (90-97%) compared to CLSI standards for anidulafungin, micafungin, posaconazole, and voriconazole.
- Accuracy for caspofungin was 80%, with significant "very major" errors (55%).
- Major and very major error rates varied by drug and species, with C. glabrata and C. parapsilosis showing more assessment discrepancies.
Conclusions:
- Agar dilution screening using CHROMagar Candida medium is a rapid, accurate, and effective method for assessing yeast susceptibility to newer antifungal agents.
- The method shows promise for routine susceptibility screening, but careful consideration of species-specific performance is required for resistance determination.
- Further optimization may be needed to improve the accuracy of resistance detection, particularly for certain drug-species combinations.
