CLSI VET06

Susceptibility testing is indicated for any organism that contributes to an infectious process warranting antimicrobial chemotherapy. If the susceptibility of a bacterial pathogen to antimicrobial agents cannot be predicted based on the identity of the organism alone, in vitro antimicrobial susceptibility testing of the organism isolated from the disease processes in animals is indicated.

A variety of laboratory techniques can be used to measure the in vitro susceptibility of bacteria to antimicrobial agents. Clinical and Laboratory Standards Institute document VET06—Methods for Antimicrobial Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria Isolated From Animals describes the standard disk diffusion method, as well as standard broth dilution (macrodilution and microdilution) and agar dilution techniques for infrequently isolated or fastidious bacteria from animals. It also includes procedures designed to standardize test performance. The performance, applications, and limitations of the current CLSI-recommended methods are described.

The tabular information in this document presents test conditions, QC recommendations, agents to consider for primary testing, and breakpoints. In an increasing number of compounds for which veterinary-specific breakpoints are not available, human breakpoints are used. As more veterinary-specific information becomes available, these changes will be incorporated into future revisions of this document.