About Erythromycin Macrolide Antibiotic. Mechanism of Action of Erythromycin Erythromycin is a member of macrolide antibiotics. It binds to the 50S sub unit of bacterial ribosome and inhibits translocation.ie: they interfere with the transfer of the newly formed peptide chain from the A site to the P site and fails to expose the A site .So that A site is unable to bind with the next aminoacyl t RNA complex. This leads to premature termination of amino acid chain and there by inhibits protein synthesis. Indications for Erythromycin 1.Tonsilitis 2.Pharyngitis 3.Pneumonia 4.Diphtheria 5.Pertusis 6.Tetanus 7.SABE 8.Syphilis 9.Gonorrhea 10.Wound and burn infection 11.Rheumatic fever 12.Acne