Long Story Short: Establishing Breakpoints for Antimicrobials and 2023 Updates

Purpose of Review This review outlines the process of setting and revising Clinical and Laboratory Standards Institute (CLSI) breakpoints and summarizes breakpoints approved in 2023. These breakpoints will be published in the 2024 edition of the CLSI M100 document. Recent Findings Over the past decade, new rapid diagnostic tests and antibiotic approvals have led to more frequent updates and revisions to clinical breakpoints—or susceptibility test interpretive criteria (STIC). CLSI is currently the only recognized standards development organization—outside of the FDA—allowed to set or revise STIC. The process of setting breakpoints is not always clear-cut because data evaluation can be limited by a lack of published data in one of three required categories (microbiologic, pharmacokinetic/pharmacodynamics, and clinical outcomes) detailed in the CLSI M23 document. Summary Antimicrobial susceptibility testing is a foundation for optimal antimicrobial therapy and plays a critical role in monitoring the spread of antimicrobial resistance.