Trends in antifungal susceptibility testing using CLSI reference and commercial methods.

Area of Science:

• Clinical microbiology
• Antifungal drug development
• Infectious disease diagnostics

Background:

• Antifungal susceptibility testing is crucial for identifying resistance and monitoring treatment efficacy.
• Standardized methods are essential for reproducible and reliable antifungal testing.
• The Clinical and Laboratory Standards Institute (CLSI) has established guidelines for testing yeasts and molds.

Purpose of the Study:

• To review the current CLSI guidelines for antifungal susceptibility testing.
• To identify areas where standard parameters and guidelines are still lacking.
• To highlight the ongoing development of testing methodologies for specific fungi and agents.

Main Methods:

• Review of CLSI M27 and M38 series documents for yeast and mold antifungal susceptibility testing.
• Identification of established quality control (QC) and interpretative breakpoint parameters.
• Assessment of recently developed guidelines and areas under development.

Main Results:

• CLSI provides established methods and breakpoints for many antifungal agents against common yeasts (e.g., Candida spp.) and molds.
• Recent guidelines address echinocandins against molds, dermatophytes, and a disk-diffusion method for molds.
• Standard parameters for minimum fungicidal concentration, QC strains, and testing Malassezia spp. are under development.
• Breakpoints are unavailable for Cryptococcus neoformans, dermatophytes, Malassezia spp., and specific agents like posaconazole and amphotericin B against yeasts.

Conclusions:

• CLSI has made significant progress in standardizing antifungal susceptibility testing for yeasts and molds.
• Further development is needed to establish comprehensive guidelines for all relevant fungal pathogens and antifungal agents.
• Ongoing research and guideline development are critical for advancing antifungal therapy and resistance monitoring.