WARNING: We do not support Internet Explorer. It is not secure and will not work correctly. Please come back using a newer web browser.

Learn About CLSI’s Free AST Rationale Documents


Understanding how CLSI’s antimicrobial susceptibility testing (AST) breakpoints and interpretive categories are determined is important for medical laboratories, drug and device manufacturers, and regulatory and accreditation organizations. To answer this question, CLSI publishes rationale documents that provide the scientific reasons behind the decisions related to breakpoint and interpretive categories, along with documentation of the standardized data and methods used to determine breakpoints.

CLSI’s subcommittee on Antimicrobial Susceptibility testing is responsible for reviewing data from many sources and studies to establish AST test methods, breakpoints, and quality control ranges. Sources for the data include in vitro, pharmacokinetic-pharmacodynamic, and clinical studies. This is accomplished through CLSI’s voluntary consensus process, which ensures a fair and balanced approach to AST standards development that allows all stakeholders to contribute.

Romney M. Humphries, PhD, D(ABMM), author of MR01 and co-author of MR02 said, “The rationale documents are a really exciting part of CLSI’s movement to work with FDA towards harmonized AST standards between these two organizations. The primary purpose is to develop data for submission to the federal register for FDA review, but in addition to improve transparency on how CLSI arrives at breakpoints. Users of M100 can also find useful information in the rationale documents, including estimated impact of breakpoint updates on antibiograms, doses used for breakpoint decisions, summary of clinical data, and a summary of the AST subcommittee’s deliberations on the breakpoint.”

Learn more about CLSI’s AST rationale documents and download them for free at clsi.org/meetings/ast/rationale-documents/.


← Go Back