CLSI M100 Tables 1 Overhaul: Modernising AST Reporting for Antimicrobial Stewardship
This review introduces the substantially revised CLSI M100-Ed33 Tables 1, which guide how clinical laboratories select and report antimicrobial susceptibility results. The update reflects the expanded antibiotic armamentarium, emerging resistance mechanisms, and growing MDR prevalence, with renewed emphasis on selective and cascade reporting to support institutional stewardship programs.
The original study
Guiding antimicrobial stewardship through thoughtful antimicrobial susceptibility testing and reporting strategies: an updated approach in 2023.
- Authors
- Pierce VM, Bhowmick T, Simner PJ
- Journal
- Journal of clinical microbiology
- Type
- Journal Article, Review
- PMID
- 37768094
Original abstract
Antimicrobial susceptibility test and report guidelines are an important tool for antimicrobial stewardship programs. Since 1972, Tables 1 within the Clinical and Laboratory Standards Institute (CLSI) M100 document have provided a general framework upon which clinical microbiologists and antimicrobial stewardship teams can build algorithms for susceptibility testing and reporting that meet the specific needs of their institution. Many changes were made to Tables 1 in M100-Ed33 to modernize the content to reflect the landscape of current clinical practice, including the growing armamentarium of antimicrobial agents, the emergence of new mechanisms of antimicrobial resistance, the increasing prevalence of infections caused by multidrug-resistant organisms, and updated consensus recommendations for first-choice and alternative agents for treatment. With these items in mind, the CLSI Table 1 ad hoc working group revised Tables 1 with the ultimate goal of supporting institutions in the creation of individualized test and report strategies that support local antimicrobial stewardship program initiatives. These strategies are built on the concepts of selective and cascade reporting. This minireview introduces the concept of CLSI M100-Ed33 Tables 1, describes the changes to Tables 1 introduced in 2023, and provides clinical vignettes that demonstrate how Tables 1 can be used in various scenarios to devise antimicrobial susceptibility test and report strategies.