Current status of antifungal susceptibility testing methods

Area of Science:

• Medical Mycology
• Clinical Microbiology
• Antimicrobial Resistance

Background:

• Antifungal susceptibility testing (AFST) is crucial in medical mycology.
• Standardization efforts by CLSI and EUCAST have led to established methods.
• Current methods allow susceptibility determination for specific Candida species and antifungal drugs.

Purpose of the Study:

• To review the advancements in antifungal susceptibility testing.
• To discuss the utility of validated methods and ongoing research into novel techniques.
• To highlight the importance of AFST in guiding antifungal therapy.

Main Methods:

• Review of standardized methods (CLSI, EUCAST).
• Discussion of emerging techniques: Etest, colorimetric microdilution, agar dilution, fungicidal activity assays, flow cytometry, ergosterol quantitation.
• Evaluation of method agreement with reference standards.

Main Results:

• Established MIC breakpoints enable susceptibility testing for Candida to fluconazole, itraconazole, voriconazole, and flucytosine.
• Validated utility of fluconazole AFST for optimizing candidiasis treatment.
• Emerging methods show promise but require further standardization and evaluation.

Conclusions:

• Standardized AFST and validated methods improve clinical guidance for antifungal therapy.
• Novel methods like Etest, colorimetric panels, flow cytometry, and ergosterol quantitation offer potential advantages.
• In vitro susceptibility remains one factor influencing outcomes, especially in immunosuppressed patients.