Clsi M22a3 Pdf Link

During an audit, inspectors frequently ask to see the scientific rationale behind a laboratory's media exemption list. Referencing the specific tables within the M22-A3 PDF provides instant justification.

CLSI M22-A3 is the third edition of a Clinical and Laboratory Standards Institute (CLSI) guideline titled "Methods for Antimicrobial Disk Susceptibility Tests" (note: CLSI document codes sometimes vary; M22 series specifically covers antimicrobial susceptibility testing methods and interpretive criteria). This edition updates procedures, quality-control recommendations, and interpretive criteria for disk diffusion testing of bacteria to ensure reliable, reproducible susceptibility results across clinical microbiology laboratories.

Despite this shift in U.S. regulatory practice, the standard remains a technically sound and historically important document. As noted on CLSI’s website, the standard is no longer being reviewed through their active consensus process but is being retained in their library because it is "technically valid" and of ongoing value to the international laboratory community. For international laboratories not bound by CLIA regulations, M22-A3 may still be a current and applicable resource. clsi m22a3 pdf

: Ensuring differential media produces the correct color changes or reactions (e.g., lactose fermentation on MAC).

Ensuring expected color changes or hemolytic patterns occur correctly. 2. Inoculation and Incubation Use a weak suspension of the control organism (typically 10310 cubed 10410 to the fourth power Colony Forming Units for productivity testing). During an audit, inspectors frequently ask to see

Exempt media are highly stable formulations that have demonstrated a historically low rate of manufacturing and shipping failures (typically less than 0.1%).

M22-A3 emphasizes that no system is 100% accurate for all NFB species. As noted on CLSI’s website, the standard is

Chocolate Agar (when used for fastidious organisms like Haemophilus spp. if not fully validated by the vendor) Selective media for specific fastidious pathogens Core Quality Control Parameters Detailed in M22-A3