Dear Stanley: CLSI M100–ED29:2019 Updates

Dear Stanley,

I appreciated the CLSI M100 updates you shared 2018. Do you know of any changes made in the latest edition that will impact QC?

Ashley from San Diego, CA

Dear Ashley,

I’m happy to provide a summary of the changes made to CLSI M100 M02 and M07M100 in 2019. Here’s what you need to know for QC:

  • Beta-lactam Combination Agents QC Ranges Tables 4A-2 and 5A-2
    • Added A. baumannii NCTC 13304 as a QC strain
    • Added Disk Diffusion QC ranges for:
      • E. coli ATCC® 25922™ : Cefepime-zidebactam and Imipenem-relebactam
      • P. aeruginosa ATCC® 27853™: Cefepime-zidebactam and Imipenem-relebactam
      • K. pneumoniae ATCC® 700603™: Cefepime, Imipenem, Cefepime-zidebactam and Imipenem-relebactam
      • E. coli NCTC 13353: Cefepime and Cefepime-zidebactam
      • K. pneumoniae ATCC® BAA-1705™: Imipenem and Imipenem-relebactam
      • K. pneumoniae ATCC® BAA-2814™: Imipenem and Imipenem-relebactam
      • A. baumannii NCTC 13304: Cefepime and Cefepime-zidebactam
    • Added MIC ranges for:
      • E. coli ATCC® 25922™: Meropenem-nacubactam and Nacubactam
      • P. aeruginosa ATCC® 27853: Meropenem-nacubactam and Nacubactam
      • E. coli ATCC® 35218™: Cefpodoxime
      • K. pneumoniae ATCC® 700603™: Cefpodoxime
      • E. coli NCTC 13353: Cefpodoxime
      • K. pneumoniae ATCC® BAA-2814™: Meropenem-nacubactam and Nacubactam
    • NOTE: There is a typo on Table 4A-2 for K. pneumoniae ATCC® 700603™. The box for Ceftolozane-tazobactam should be green. This was accidentally omitted. The free M100 online version is corrected, but print versions may not be.
  • Added QC Ranges for Neisseria gonorrhoeae ATCC® 49266™ to Disk Diffusion QC Ranges for Fastidious Organisms Table 4B for Azithromycin and Gepotidacin

All these changes and more are listed under the Overview of Changes in the applicable CLSI standards.

Visit our website to find the QC strains your lab needs to meet CLSI standards. Our Technical Support team is available at or 1.320.229.7045 to help you determine the right strain and format for your lab.


Stanley Staphylococcus

Stanley Staphylococcus is a Master Micro-Technologist at Microbiologics, where he is responsible for helping customers understand why microorganisms behave the way they do. You could say he’s somewhat of a psychologist. Microbiologics has been lucky to have Stanley, a graduate of Gram-Positive Cocci University, as a member of their renowned Technical Support Team for over 20 years. Stanley says his favorite type of people are microbiologists and he enjoys traveling far and wide to meet them. Amazingly, Stanley has been on every continent – even Antarctica!

How to submit inquiries: There are two ways to get Stanley’s help. You can email your questions to or you can simply submit an inquiry from our Dear Stanley page. For urgent issues, please contact our Technical Support Team at or 1.320.229.7045.

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