E-Mycin n : an antibiotic (trade name Erythrocin or E-Mycin or Ethril or Ilosone or Pediamycin) obtained from the actinomycete Streptomyces erythreus; effective against many Gram-positive bacteria and some Gram-negative [syn: {erythromycin}, {Erythrocin}, {Ethril}, {Ilosone}, {Pediamycin}]