Related Experiment Video
Updated: Aug 26, 2025
Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance
Published on: December 28, 2017
Acquired fluconazole resistance and genetic clustering in Diutina (Candida) catenulata from clinical samples
Céline Nourrisson1, Maxime Moniot2, Rose-Anne Lavergne3
1Université Clermont Auvergne, Inserm, 3IHP, Centre Hospitalier Universitaire Clermont-Ferrand, Service de Parasitologie-Mycologie, Clermont-Ferrand, France; Université Clermont Auvergne/Inserm U1071, USC-INRAe 2018, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte, Clermont-Ferrand, France.
Objectives:
Diutina (Candida) catenulata is an ascomycetous yeast isolated from environmental sources and animals, occasionally infecting humans. The aim of this study is to shed light on the in vitro antifungal susceptibility and genetic diversity of this opportunistic yeast.
Methods:
Forty-five D. catenulata strains isolated from various sources (including human and environmental sources) and originating from nine countries were included. Species identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed via internal transcribed spacer ribosomal DNA barcoding. In vitro antifungal susceptibility was determined for seven systemic antifungals via the gradient strip method after 48 hours of incubation at 35°C using Etest® (Biomérieux) or Liofilchem® strips. Isolates exhibiting fluconazole minimal inhibitory concentrations (MICs) of ≥8 μg/mL were investigated for mutations in the ERG11 gene. A novel microsatellite genotyping scheme consisting of four markers was developed to assess genetic diversity.
Results:
MIC ranges for amphotericin B, caspofungin, micafungin, isavuconazole, and posaconazole were 0.19-1 μg/mL, 0.094-0.5 μg/mL, 0.012-0.064 μg/mL, 0.003-0.047 μg/mL, and 0.006-0.032 μg/mL, respectively. By comparison, a broad range of MICs was noted for fluconazole (0.75 to >256 μg/mL) and voriconazole (0.012-0.38 mg/L), the higher values being observed among clinical strains. The Y132F amino acid substitution, associated with azole resistance in various Candida species (C. albicans, C. tropicalis, C. parapsilosis, and C. orthopsilosis), was the main substitution identified. Although microsatellite typing showed extensive genetic diversity, most strains with high fluconazole MICs clustered together, suggesting human-to-human transmission or a common source of contamination.
Discussion:
The high rate of acquired fluconazole resistance among clinical isolates of D. catenulata is of concern. In this study, we highlight a link between the genetic diversity of D. catenulata and its antifungal resistance patterns, suggesting possible clonal transmission of resistant isolates.
Insights
High fluconazole resistance in Diutina (Candida) catenulata clinical isolates is a concern. Genetic diversity is linked to antifungal resistance patterns, suggesting potential clonal transmission of resistant strains.
Area of Science:
- Medical Mycology
- Antimicrobial Resistance
- Yeast Genetics
Background:
- Diutina (Candida) catenulata is an opportunistic yeast found in environmental and animal sources, with occasional human infections.
- Understanding its antifungal susceptibility and genetic diversity is crucial for managing infections.
Purpose of the Study:
- To investigate the in vitro antifungal susceptibility of Diutina (Candida) catenulata.
- To analyze the genetic diversity of D. catenulata strains.
- To explore the relationship between genetic diversity and antifungal resistance.
Main Methods:
- Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and ITS sequencing for species identification.
- Gradient strip method (Etest® or Liofilchem®) for in vitro antifungal susceptibility testing against seven systemic antifungals.
- ERG11 gene sequencing for azole-resistant isolates and development of a novel microsatellite genotyping scheme.
Main Results:
- A broad range of minimum inhibitory concentrations (MICs) was observed for fluconazole (>256 μg/mL) and voriconazole (0.38 mg/L), particularly in clinical strains.
- The Y132F amino acid substitution in the ERG11 gene was the primary azole resistance marker identified.
- Microsatellite typing revealed extensive genetic diversity, with high fluconazole-resistant strains clustering together.
Conclusions:
- Acquired fluconazole resistance in clinical Diutina (Candida) catenulata isolates is a significant concern.
- A link exists between the genetic diversity of D. catenulata and its antifungal resistance profiles.
- Findings suggest possible clonal transmission of fluconazole-resistant D. catenulata isolates.
