Erythromycin Ethylsuccinate A macrolide antibiotic, produced by Streptomyces erythreus. This compound is an ester of erythromycin base and succinic acid. It acts primarily as a bacteriostatic agent. In sensitive organisms, it inhibits protein synthesis by binding to 50S ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins.