Related Experiment Video
Updated: Apr 20, 2026
Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance
Published on: December 28, 2017
Genotypic, phenotypic, and proteomic characterization of Candida glabrata during sequential fluconazole exposure
Yuthika Hemamala Samaranayake1, Becky Pik Ki Cheung, Joyce Yick Yee Yau
1Department of Oral Biosciences, Faculty of Dentistry, University of Hong Kong, Hong Kong, China.
Aim:
Candida glabrata is a major pathogen in humans known to be intrinsically resistant to fluconazole. However, genotypic, phenotypic, and proteomic changes associated with reduced susceptibility to fluconazole are not properly understood. The aim of this study was to observe specific phenotypic, chromosomal, and proteomic alterations in a Candida glabrata strain sequentially exposed to fluconazole.
Methods:
Candida glabrata was exposed to increased concentrations of fluconazole in RPMI for 55 days. Phenotypic changes were evaluated using standard assays. Molecular/proteomic changes in C. glabrata were analyzed by contour-clamped homogeneous electric field electrophoresis, reverse transcription-polymerase chain reaction, and mass spectrometry.
Results:
Candida glabrata demonstrated increased fluconazole resistance (>256 μg/mL), with extensive cross-resistance to ketoconazole (0.38-3.0 μg), itraconazole (8 to >32 μg), and voriconazole (0.125-1.5 μg). Morphologically dissimilar colonies on RPMI/fluconazole agar demonstrated variable chromosomal profiles compared with the control isolate. Stable chromosomal changes were associated with a significantly higher (P<0.05) mRNA level of the hemolysin gene compared with the control. Phenotypic switching on CuSO4 agar was associated with variable metallothionein mRNA transcription levels. The proteome analysis of a fluconazole-resistant offshoot demonstrated a total of 98 protein spots, 25 showing a twofold upregulation.
Conclusion:
Fluconazole exposure initiates the chance evolution of a new colonizing population with specific virulence traits.
Insights
Sequential fluconazole exposure in Candida glabrata led to increased antifungal resistance and significant chromosomal and proteomic alterations. This evolution results in a new population with enhanced virulence traits.
Area of Science:
- Mycology
- Antimicrobial Resistance
- Molecular Biology
Background:
- Candida glabrata is a significant human pathogen.
- It exhibits intrinsic resistance to fluconazole.
- Mechanisms of reduced fluconazole susceptibility require further elucidation.
Purpose of the Study:
- To investigate phenotypic, chromosomal, and proteomic changes in Candida glabrata upon sequential fluconazole exposure.
- To understand the evolution of fluconazole resistance in this species.
Main Methods:
- Sequential exposure of Candida glabrata to increasing fluconazole concentrations over 55 days.
- Phenotypic analysis using standard assays.
- Molecular and proteomic analyses including CHEF electrophoresis, RT-PCR, and mass spectrometry.
Main Results:
- Significant increase in fluconazole resistance (>256 μg/mL) and cross-resistance to other azoles.
- Variable chromosomal profiles and increased hemolysin gene mRNA levels in resistant strains.
- Proteomic analysis revealed 25 protein spots with twofold upregulation in resistant isolates.
Conclusions:
- Fluconazole exposure drives the evolution of a new Candida glabrata population.
- This emergent population possesses distinct virulence characteristics.
