中文摘要：

耐甲氧西林金黄色葡萄球菌（MRSA）的产生是由甲氧西林敏感的金黄色葡萄球菌（MSSA）获得外源性的SCCmec所致。MRSA菌株可以产生一种新的青霉素结合蛋白PBP2a,PBP2a降低了与β-内酰胺类抗生素的亲合力,从而对β-内酰胺类抗生素产生耐药性。PBP2a由mecA基因编码,mecA基因存在于葡萄球菌盒式染色体（Staphylococcal cassette chromosome mec,SCCmec）中,SCCmec是一种可移动的遗传元件,该元件还携带除mecA基因外的其他抗菌药物的耐药基因,造成多重耐药（Multidrug-resistance,MDR）。SCCmec目前主要分为8型,其中又分为若干亚型。SCCmec的基因型与MRSA的流行背景有关,不同地区的SCCmec基因分型分布可能不同。

英文摘要：

Methicillin-resistant Staphylococcus aureus was generated when methicillin-susceptible Staphylococcus aureus acquired an exogenous staphylococcal cassette chromosome mec（SCCmec）.Methicillin resistance in staphylococci was based on the expression of a novel penicillin-binding protein 2a（PBP 2a）,which had a low-affinity for the β-lactam antibiotics,thus,it resisted β-lactam antibiotics.The presence of mecA,a gene coding for the penicillin-binding protein PBP2a,carried by a mobile genetic element designated staphylococcal cassette chromosome mec（SCCmec）.SCCmec was a mobile genetic element that harbored the methicillin resistant gene（mecA） and other antibiotic resistance determinants,resulting in a multiple drug resistance（multidrug-resistance,MDR）.SCCmec elements were currently classified into types I to VIII,and were further classified into subtypes.The genotype of SCCmec was related to epidemic background of MRSA,there may be different distribution of SCCmec genotyping in different areas.