scope:

This standard describes standard broth (macrodilution and microdilution) and agar dilution methods for determining in vitro susceptibility to antimicrobial agents for bacteria that grow aerobically and includes:

• Broth and agar dilution test preparation

• Testing conditions, including inoculum preparation and standardization, incubation time, and incubation temperature

• Reporting minimal inhibitory concentration (MIC) results

• QC procedures

• Dilution test method limitations

To assist the medical laboratory, suggestions are provided for selecting antimicrobial agents for routine testing and reporting.

Standards for testing the in vitro antimicrobial susceptibility of bacteria that grow aerobically using the antimicrobial disk testing method are found in CLSI document M02. Standards for testing the in vitro antimicrobial susceptibility of bacteria that grow anaerobically are found in CLSI document M11. Guidelines for standardized antimicrobial susceptibility testing (AST) of infrequently isolated or fastidious bacteria that are not included in CLSI documents M02, M07, or M11 are available in CLSI document M45. The AST methods provided in this standard can be used in laboratories around the world including but not limited to:

• Medical laboratories

• Public health laboratories

• Research laboratories

• Food laboratories

• Environmental laboratories