One of the most significant aspects of the M22-A3 document is the list of media that do not require retesting by the user, provided the manufacturer is certified. This is often referred to as "exempt" media.
"Dear CLSI,
According to the CLSI website, effective January 1, 2016, the Centers for Medicare & Medicaid Services (CMS) requires that laboratories performing non‑waived testing must either: clsi m22a3 pdf link
Provides clear protocols for handling media that fail physical or biological inspections. 4. How to Access and Download CLSI M22-A3
Microbiological culture media are the foundation of diagnostic bacteriology. If the medium fails to support the growth of a pathogen or fails to inhibit commensal flora as intended, the clinical result could be a false negative, leading to misdiagnosis. The M22-A3 standard balances the need for rigorous safety with the practicalities of laboratory workflow. 2. The Concept of "Exempt" Media One of the most significant aspects of the
: Having the official document on hand ensures that inspectors can verify the scientific rationale behind your QC exemptions. Finding a Legitimate CLSI M22-A3 PDF Link
The Clinical and Laboratory Standards Institute (CLSI) is a globally recognized, not-for-profit membership organization that develops clinical laboratory standards based on a rigorous consensus process. Its mission is to "foster excellence in laboratory medicine by developing and implementing clinical laboratory standards and guidelines". The standards produced by CLSI are developed through the substantial agreement of materially affected, competent, and interested parties—experts who volunteer their time and knowledge to advance public health. The M22-A3 standard balances the need for rigorous
Because CLSI standards are copyrighted intellectual property, they are not typically available as free PDF downloads. To obtain a legal copy of the M22-A3 standard, you can visit the following official sources:
The complete standard package contains several critical sections. The document is 44 pages in length and contains comprehensive guidance on quality control for clinically significant microorganisms. While the full standard is protected by copyright, a free "front matter" (preliminary pages) sample is publicly available for educational purposes.
These media require routine quality control testing by the user laboratory.
For laboratories outside the United States, . Many international facilities continue to use this standard as their primary reference for quality control of commercially prepared microbiological culture media.