CLSI M22-A3, "Quality Control for Commercially Prepared Microbiological Culture Media," establishes protocols for testing ready-to-use media, emphasizing an acceptable failure rate of ≤0.5% for exempt media. While it defines responsibilities for QC, U.S. laboratories have transitioned from these exemptions to Individualized Quality Control Plans (IQCP). Purchase the document through the CLSI Shop.
The CLSI M22-A3 standard, titled "Quality Control for Commercially Prepared Microbiological Culture Media; Approved Standard—Third Edition," provides essential quality assurance procedures for both manufacturers and laboratory users. Core Content Overview
Compared to previous versions, this third edition introduced several refinements: Failure Rate Cutoff : Increased from Fastidious Organisms clsi m22a3 pdf
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Visual Inspection Criteria: Even for exempt media, labs must check for physical defects such as: Cracked Petri dishes or tubes. Excessive bubbles or rough surfaces. Obvious contamination or hemolysis. Incorrect agar depth (less than 3 mm) or unequal filling. Purchase the document through the CLSI Shop
Failing to follow the M22-A3 standard can have serious real-world consequences:
For the chromatographer at the bench, the M22-A3 PDF is a technical playbook. Here are the five pillars the document emphasizes. Excessive bubbles or rough surfaces
Commercial systems use numerical biocodes (profiles). M22-A3 highlights specific "rare biocodes" that should be questioned.