BIVR test of the representative strains. The class of MRSA and the strain number are shown in the figure. Upper panels show photographs of the representative strains and the lower panels show the respective transformants with the plasmid pN315. K1179 was a non-BIVR MRSA harbouring the blaZ gene and producing a high level of β-lactamase. Hence, a transformant was not available. xx μg/ml denotes the concentration of ceftizoxime in the disk.