FDA U.S. Food and Drug Administration Notice: ArchivedDocument The content in this document is provided on the FDA's website for reference purposes only. It was current when produced, but is no longer maintained and may be outdated. Importance of Macrolides in Veterinary Medicine Mike Apley, DVM, PhD Veterinary Diagnostic and Production Animal Medicine Iowa State University Macrolides in Veterinary T Medicine 14 member ring erythromycin 16 member ring I tylosin, tilmicosin Macrolide Susceptibility Testing The macrolide breakpoints reported here are adapted from the NCCLS M31-A2 document. The extended range information reflects extended dilutions used by some diagnostic laboratories utilizing microwell dilution systems Of the macrolides, only tilmicosin has NCCLS validated breakpoints for veterinary applications NCCLS macrolide breakpoints Drug Intermediate Extended Susceptible Resistant Range (≤ μg/ml) (μg/ml) (≥μg/ml) (μg/ml) Erythromycin 0.25 - 4 (Adapted from human) 0.5 1-4 Organisms other than streptococci 8 0.25 0.5 Streptococci 1 Tilmicosin (Veterinary derived) 4 -32 8 16 32 Cattle (BRD) P. hemolytica Swine respiratory disease 16 32 Actinobacillus pleuropneumoniae Pasteurella multocida Label Applications Label applications in this presentation are adapted from labels as presented in the Compendium of Veterinary Products (North American Compendiums) The listing of a label application does not indicate the frequency or extent of use in animals. Label Applications in Food Animals Tylosin LabelIndications