Association of a Penicillin Resistance Gene with a Tetracycline Resistance Plasmid (P TP–2 ) in Staphylococcus aureus

Abstract

On transduction with a lysogenic strain of Straphylococcus aureus isolated from a clinical specimen and having tetracycline (TC)-penicillin (PC)-chloramphenicol (CP)-resistant plasmids, the three-drug-resistant strain was frequently obtained. By repeatedly transducing from this strain, a strain (TP-2) having stable resistance to TC and PC could be obtained. In transformation with the deoxyribonucleic acid (DNA) of TP-2 as donor, all of the transformants obtained by selecting with either TC or PC were both TC and PC resistant. According to electron microscopy study of the covalently closed circular DNA of TP-2, the plasmid DNA size was 1.37 ± 0.03 μm (2.84 × 10 6 daltons). The plasmid (P TP-2 ) is presumed to be a new plasmid in which the PC resistance gene was integrated into the TC-resistant plasmid.