Which (e.g., CAP, Joint Commission, local government) audits your laboratory?
The standard explicitly applies to , ready-to-use microbiological culture media. It does not cover media prepared entirely in-house from raw ingredients (though those labs may still use it as a reference). Intended users include clinical labs, public health labs, veterinary diagnostics, and industrial microbiology facilities.
The most impactful contribution of CLSI M22-A3 is the categorization of culture media into two distinct groups based on historical failure rates: and Non-Exempt . 1. Exempt Media (Qualifying for Reduced QC)
A central concept of CLSI M22-A3 is the division of quality control obligations. clsi m22a3 pdf
: Must document the receipt and physical condition of every shipment, checking for defects like cracked plates, contamination, or unequal filling. Wadsworth Center Key Technical Updates in M22-A3
The official CLSI M22-A3 document is available for purchase in PDF or hard copy formats through authorized distributors:
Disclaimer: This article is for informational purposes only and does not constitute legal or regulatory advice. Standards and regulations regarding the use of CLSI documents are subject to change. Always consult the official CLSI organization for the most current guidelines and licensing agreements. Which (e
Through extensive multi-center studies, CLSI determined that certain types of commercially prepared media have exceptionally low failure rates (often less than 0.1%). Under M22-A3, if a laboratory purchases these media from a manufacturer that certifies compliance with CLSI standards, the laboratory is from performing full, routine microbial performance testing on those batches. Examples of typically exempt media include: Sheep Blood Agar (SBA) MacConkey Agar (MAC)
M22-A3 distinguishes between simple linear regression (y = mx + b) and more complex weighted regression (e.g., 1/x or 1/x²). It warns that heteroscedasticity (increasing variance at high concentrations) is common in LC. The guideline provides statistical methods (e.g., lack-of-fit F-test) to verify the calibration model.
: These are common, highly stable media types (like Blood Agar or MacConkey Agar) that have a proven track record of high quality from manufacturers. For these, laboratories can rely on the manufacturer's QC certificate rather than performing full in-house retesting, provided the lab verifies the storage conditions and physical integrity. Intended users include clinical labs, public health labs,
Users must still perform a physical inspection of every lot upon receipt. Available as a PDF download from
Understanding CLSI M22-A3: The Standard for Quality Control of Microbiological Culture Media