Deoxyribonucleic acid sequence common to staphylococcal and streptococcal plasmids which specify erythromycin resistance.

Plasmids from erythromycin-resistant Staphylococcus aureus, Streptococcus sanguis, and Streptococcus faecalis show deoxyribonucleic acid sequence homology. The homologous sequences can be localized to specific restriction endonuclease fragments, which in the case of S. aureus plasmid pI258 involves a single fragment from either EcoRI or HindIII digest known to contain the erythromycin resistance determinant. Complementary ribonucleic acid probes prepared from S. aureus plasmid pI258 and S. sanguis plasmid pAM77 also hybridize to specific fragments in restriction endonuclease digests of deoxyribonucleic acid from erythromycin-resistant Streptococcus progenes and Streptococcus pneumoniae. These studies suggest a common origin for a class of erythromycin resistance determinants in unrelated strains of pathogenic bacteria for which exchange of genetic material has not been demonstrated.