Join us in celebrating our 50th Anniversary!
Join us in celebrating our 50th Anniversary!

About CLSI’s Subcommittee on Antimicrobial Susceptibility Testing (AST)

About the Subcommittee on AST Standards

The Subcommittee on AST provides useful information to laboratories, enabling them to advise clinicians in the selection of appropriate antimicrobial therapy.

Volunteers for the Subcommittee on AST come from microbiology laboratories, government agencies, and pharmaceutical and diagnostic microbiology industries. 

Together, they focus on the following key elements:

  • Developing standard reference methods for antimicrobial susceptibility tests
  • Providing quality control parameters for standard test methods
  • Establishing interpretive criteria for results of standard antimicrobial susceptibility tests
  • Providing suggestions for testing and reporting strategies that are clinically relevant and cost-effective
  • Continually refining standards and guidelines, thereby optimizing the detection of emerging resistance
  • Educating users through multimedia communication of standards and guidelines
  • Fostering a dialogue with users of these methods and those who apply them

As a result, the interests of the professions, government, and industry remain balanced and aimed at a single common interest—quality medical testing.

View AST Meeting Files and Resources 


  • RangeFinder— Microsoft Excel spreadsheet calculators that have the capacity to provide first estimates of quality control ranges for studies that have followed the CLSI M23 standard to establishing ranges.
  • ECOFFinder — Microsoft Excel spreadsheet calculator designed to estimate epidemiological cutoff values (ECVs, ECOFFs) for the minimal inhibitory concentrations or minimal effective concentrations of wild-type bacterial or fungal populations.
  • M100 Archive Table — PDF document of breakpoints eliminated from CLSI document M100 since 2010.
  • Disclosure of Interest
  • AST Subcommittee Orientation 2018
  • CLSI together with CAP and ASM are coordinating preparation and distribution of materials to help you address the CMS requirement for implementation of IQCP (Individualized Quality Control Plan) by January 1, 2016.
    • AST IQCP Materials
    • IQCP for Disk Diffusion AST
    • PowerPoint Presentations (6/8/2015)
      • Overview of CMS’ Vision for IQCP in Clinical Microbiology - Nancy Anderson, MMSc, MT(ASCP)
      • IQCP - Guidelines and Template for Getting Started - Linda C. Bruno, MA, MT(ASCP)
      • Pulling It All Together - Real Life IQCP Examples - Susan E. Sharp, PhD, (D)ABMM, F(AAM)
      • List of Microbiology tests not requiring IQCP - Linda C. Bruno, MA, MT(ASCP)