Tylosin exerts antibacterial effects by binding to 23S rRNA of the bacterial ribosomal 50S subunit . Tylosin also prevents growth of Gram-negative strains, with MICs of 64 μg/mL, 32 μg/mL, 512 μg/mL and 1 μg/mL for M. haemolytica 11935, P. multocida 4407, E. coli ATCC 25922 and E. coli AS19rlmA I , respectively.