The CLSI M45 document, titled "Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria," is a specialized reference standard. It bridges the gap left by broader standards like CLSI M100 (which focuses on common mainstream pathogens).
Use a direct colony suspension method (0.5 McFarland standard), verified by spectrophotometer. M45 warns that prolonged broth incubation before dilution alters results for fastidious species.
Includes Corynebacterium spp., Micrococcus spp., and Abiotrophia spp./ Granulicatella spp.. clsi document m45 pdf
The current edition is the , originally published in August 2016.
The M45 document is organized by genus and species. When you download the CLSI M45 PDF, you will find detailed sections for: The CLSI M45 document, titled "Methods for Antimicrobial
Mueller-Hinton broth supplemented with 2% to 5% lysed horse blood for fastidious organisms.
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. M45 warns that prolonged broth incubation before dilution
The M45 guideline is not a static document. The CLSI is actively working on a , with discussions and data review well underway. Based on meeting minutes, the final draft for the 4th edition was targeted for February 2024 to allow for publication in 2025. Emerging data, such as that for Aerococcus spp., are being used to propose changes to the guideline. The work to define the precise roles of M45 and M100 is also ongoing, with efforts to develop clear definitions for what constitutes an M100 organism versus an M45 organism.
: Breakpoints in M45 are often based on less data (e.g., fewer PK/PD or clinical outcome studies) than those in M100, sometimes requiring extrapolation from related species. Access and Format
Standard reference documents like CLSI M100 cover the vast majority of routine clinical isolates. However, relying solely on M100 leaves a dangerous gap when an unusual organism emerges from a clinical culture.
