The supplemental information presented in CLSI M42/M49-S1 is intended for use with the antimicrobial susceptibility testing procedures published in the following Clinical and Laboratory Standards Institute (CLSI)-approved documents: M42-A- Methods for Antimicrobial Disk Susceptibility Testing of Bacteria Isolated From Aquatic Animals; Approved Guideline; and M49-A-Methods for Broth Dilution Susceptibility Testing of Bacteria Isolated From Aquatic Animals; Approved Guideline. The guidelines contain information about both disk (M42-A) and dilution (M49-A) test procedures for bacteria isolated from aquatic animals.

The clinical importance of antimicrobial susceptibility test results requires that these tests be conducted under optimal conditions and that laboratories have the capability to interpret results.

The tabular information presented here represents the most current information (as of June 2010) for interpretation of antimicrobial susceptibility test results using the procedures standardized in M42-A and M49-A. Users should consider the interpretive criteria presented in these tables specific only to isolates of Aeromonas salmonicida, and not to any other genus or species. Fish disease diagnostic laboratories that typically conduct susceptibility tests less than once per week should consult this supplement for revised guidance for frequency of quality control.