Fig. 3

a Hemolytic activity of representative CC522 S. aureus isolates on Columbia Blood Agar (CBA). Positive control: highly invasive and cytotoxic strain S. aureus 6850. Colony sizes might differ due to different camera positions. The zone of hemolysis (β-hemolysis) is indicated with an arrow. The spa types of representative CC522 S. aureus are presented. b Mucoid CC522 isolates on CBA and CRA. Key: A: Columbia Blood Agar (CBA); B: Congo Red Agar (CRA). A, B, C, D: mucoid phenotype; A1, B1, D1, E: pink/brown colonies with wrinkled, irregular edges; C1: brown colonies with smooth, convex, entire edges; F: pink colonies with smooth, convex, entire edges. Positive control: RP62A—S. epidermidis (biofilm-positive); 70518005-I: cystic fibrosis (CF) S. aureus isolate with a 5 bp deletion within the intergenic region of the ica operon [32] (biofilm/PIA-positive); Negative control S. carnosus TM300 (biofilm-negative). The spa types of mucoid CC522 S. aureus are indicated. Colony morphology is highlighted, and sizes might differ due to different camera positions