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CLSI Publishes New Antimicrobial Susceptibility Testing Document


Wayne, Pennsylvania, USA—The Clinical and Laboratory Standards Institute announces the publication of M11—Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria. M11 describes the reference standard agar dilution method (Wadsworth) and the alternative broth microdilution method. Susceptibility testing of anaerobes is recommended for surveillance purposes and for specific clinical situations. The agar dilution method is well suited for surveillance testing and research. It is also the standard with which other methods are compared. The alternative method, broth microdilution, is well suited for the medical laboratory but is currently limited to testing Bacteroides spp. and Parabacteroides spp. organisms and selected antimicrobial agents. QC criteria for the agar dilution and broth microdilution are described.  

This standard includes information on:

  • Preparation of broth and agar dilution tests.
  • Testing conditions (including inoculum preparation and standardization, incubation time, and incubation temperature).
  • Reporting minimal inhibitory concentration (MIC) results.
  • QC procedures.
  • Limitations of the dilution test methods.
  • A step-by-step guide to AST.

 For more information about M11, contact Patrick McGinn at pmcginn@clsi.org or +1.484.588.5933.  

CLSI sets the standard for quality in medical laboratory testing. A not-for-profit membership organization, CLSI brings together the global laboratory community for the advancement of a common cause: to foster excellence in laboratory medicine.  

For nearly 50 years, our members, volunteers, and customers have made CLSI a respected, transformative leader in the development and implementation of medical laboratory testing standards. Through our unified efforts, we will continue to set and uphold the standards that drive quality test results, enhance patient care delivery, and improve health care around the world.  

By using CLSI standards, laboratorians can improve process quality, speed the development of standard operating procedures, and implement safer practices with greater ease and efficiency. 

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