Tylosin is a macrolide antibiotic which acts by interfering with bacterial protein synthesis. It has a spectrum of activity and mode of action similar to that of erythromycin, being usually bacteriostatic and largely active against Gram-positive aerobes like Erysipelothrix. Macrolides are well absorbed and often concentrate within cells and macrophages thereby targeting intracellular pathogens including Mycoplasmas. Unlike most antibiotics, its use is restricted to the veterinary field.