Colony-spreading responses of MRSA strains to calf serum.

Overnight cultures of MRSA NI strains (40 strains) [4] were spotted onto soft agar plates supplemented with or without calf serum (250 µl) and incubated for 8 h. Diameter ratios between plates with serum and plates without serum calculated for each strain are listed. The presence of the wild-type psm-mec gene was examined by sequencing.将40株耐甲氧西林金黄色葡萄球菌（Methicillin-resistant Staphylococcus aureus, MRSA）NI菌株[4]的过夜培养物点种于添加或不添加250 μl小牛血清的软琼脂平板上，孵育8小时。针对每株菌株，计算其含血清平板与不含血清平板的直径比值并列表展示。通过测序检测野生型psm-mec基因的存在情况。