Antifungal Susceptibility Testing: A Primer for Clinicians.

Area of Science:

• Medical Mycology
• Clinical Microbiology
• Infectious Diseases

Background:

• Antifungal susceptibility testing (AFST) informs treatment choices for fungal infections.
• Lack of established clinical breakpoints hinders interpretation of AFST results for many fungi, especially molds.
• This limits clinicians' ability to definitively categorize fungal isolates as susceptible or resistant.

Purpose of the Study:

• To provide clinicians with an overview of antifungal susceptibility testing for fungal infections.
• To discuss methods, limitations, and breakpoint establishment for AFST.
• To guide the interpretation of AFST results in the absence of established criteria and identify when testing is not indicated.

Main Methods:

• Review of current methodologies for performing antifungal susceptibility assays.
• Analysis of the process for establishing clinical breakpoints for antifungal agents.
• Examination of strategies for interpreting AFST results when clinical breakpoints are unavailable.

Main Results:

• AFST provides valuable data on antifungal activity against specific fungal isolates.
• Clinical breakpoints are not established for numerous fungal species causing invasive disease, particularly molds.
• Clinicians must contextualize results in the absence of interpretive criteria.

Conclusions:

• Understanding AFST methods and limitations is crucial for effective clinical decision-making.
• Interpretation of AFST requires careful consideration, especially when clinical breakpoints are absent.
• Appropriate utilization of AFST, including recognizing when it's not warranted, optimizes patient care for fungal infections.