Genetic analysis of resistance to erythromycin and oleandomycin in Staphylococcus aureus

Abstract

Strains U9(pase, tet, ery, nov) and U9(pase, tet, ol, nov) of Staphylococcus aureus were used as donors of the ery and ol markers, respectively, to strain 152. Thirty-three erythromycin-sensitive (ery-s) mutants of strain 152(ery) and 19 oleandomycin-sensitive (ol-s) mutants of strain 152(ol) were isolated following diethyl sulfate mutagenesis. The results of reciprocal transductions involving these mutants are as follows: (a) the frequency at which the ery and ol markers were transduced into each mutant varied greatly, and was especially low in those mutants which yielded recombinants in reciprocal transductions between the mutants; (b) 13 of the 19 ol-s mutants yielded recombinants in reciprocal transductions between the ol-s mutants; (c) no recombinants were detected in reciprocal transductions between ery-s mutants; (d) antibiotic-resistant recombinants were obtained in reciprocal transductions between three ery-s mutants and three ol-s mutants. The results of this study demonstrate that there is only one genetic locus which controls resistance to erythromycin and oleandomycin in these strains, and that it exists in an inducible state (the ery marker) and a constitutive state (the ol marker).