Fig. 4: SCCmec transformation.

a Presence of the mecA gene was verified by PCR using mecAF and mecAR primers with equal amounts of DNA template. DNA of donor and recipients was used for positive and negative controls. M: DNA size marker, λ HindIII. The experiment was repeated at least twice independently with similar results. b Stability of resistance. The transformants were passaged in drug-free media for 12 h after growth with cefoxitin (4 μg mL⁻¹) for 12h (Time 0). The percentage of cells that can grow on cefoxitin was calculated by the replica method. Bars represent the mean of n = 2 independent experiments. Data points representing independent experiments are shown by gray dots. c Disk-diffusion test of β-lactam antibiotics. CFX: cefoxitin, MPI: oxacillin. Rght bottom: diameters of inhibitory zones. d Intactness and stability of SCCmec in transformants. e–g Schematic structures of SCCmec IVa in MW2 chromosomal DNA (e), SCCmec I in COLw/oφ (COL without phage) chromosomal DNA (f), and of SCCmec II in N315 chromosomal DNA (g). Primer locations are indicated with arrows. Primers attL-F and attR-R can also amplify the nonintegrated SCCmec IVa (e). Primers 3.0-R and Xsau325 locate outside of SCC and specifically amplify the chromosomally integrated SCCmec I and II (f, g). DNA of MR donors and MSSA recipients was used for positive and negative controls. Suffix (1), (2) represents transformants obtained from two independent experiments. (e–g, bottom) Long PCR verification of the entire SCCmec IVa (e), I (f), or II (g) elements in transformants where mecA was present. M: DNA size marker, λ HindIII. Source data are provided as a Source Data file.