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About CLSI



For 30 years, the microbiology community has relied on CLSI’s annually updated M100 document as the gold standard for the latest, most trusted AST breakpoint data.

Now the reference you reach for is even more easily accessible, in a variety of brand new formats to fit your unique laboratory environment and working preferences.

3 Ways to Get Your Go-to Guidance

M100 Document


M100-S27: Performance Standards for Antimicrobial Susceptibility Testing

This document provides updated tables for the Clinical and Laboratory Standards Institute antimicrobial susceptibility testing standards M02-A12,
M07-A10, and M11-A8.

Great for in-laboratory use that all staff can readily reference!

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Our Searchable Online Version of M100

Full online access to M100, with added functionality and fast, easy data searching in an electronic format. Plus, you’ll have the added benefit of quick access to related materials via an exclusive AST Resource Center.

Ideal for finding specific breakpoints based on your unique bug/drug combination!

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The Read-Only Web Version
of M100

You can now quickly reference the most trusted AST breakpoints from anywhere with an Internet connection! M100 is available online as a convenient companion to the M100 document.

Perfect for finding key breakpoint data when and where you need it!


Why Make CLSI’s M100 Your Reference of Choice?


Not only has CLSI long been the world-leading provider of AST breakpoints, methods, and quality control standards, but we are also the only organization in the world designated as a WHO collaborating center for creation of medical laboratory standards. CLSI is also the only organization of its kind with an inclusive, transparent standards development process. Through equal balance of input among industry, government, and health care professionals, we protect against the threats of opaque decision-making and conflicted data.

No other organization provides this level of process transparency and balance, which helps ensure that M100 is widely upheld as the go-to publication for real-time identification of emerging bacterial resistance patterns—as agreed upon by the medical laboratory community. Learn more about our unique consensus-based process here.


AST News Update – June 2017

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Many Voices, One Goal
Become part of the global community that is driving better health care outcomes.

Did You Know?

CLSI distributes more than
75,000 standards and guidelines per year, worldwide.


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