SCCmec遗传元件及其在耐甲氧西林金黄色葡萄球菌分子分型中的应用

携带mec基因簇的葡萄球菌盒式染色体(Staphylococcal chromosome cassette mec, SCCmec)遗传元件的获得是耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus, MRSA)耐药的主要原因。SCCmec由一个mec基因簇、一个染色体重组酶(ccr)基因簇及3个J区组成。mec基因簇含有mecA及其调控基因,mecA基因编码的耐药决定簇使MRSA对β-内酰胺类抗生素耐药;ccr基因簇编码的重组酶负责SCCmec元件的整合与切离;J区差异大,导致不同来源MRSA菌株携带SCCmec的大小不一,在组成上也具有多样性。这些特征为利用SCCmec元件进行MRSA分型创造了条件。文章介绍了SCCmec元件的结构和功能,综述了基于SCCmec的MRSA分型研究。

Application of the SCCmec element in the molecular typing of methicillin-resistant Staphylococcus aureus

Acquisition of the staphylococcal chromosome cassette mec (SCCmec) is one of the key reasons for the resistance of methicillin-resistant Staphylococcus aureus (MRSA). SCCmec is composed of a mec gene complex encoding the PBP2a determinant that is responsible for the β-lactam resistance of MRSA, and a ccr gene complex encoding recombinases that mediate the integration of SCCmec into and its excision from the recipient chromosome, and so-called three junkyard (J) regions of different sizes. The SCCmec elements carried by MRSA from different geographic locations are diverse, and each type contains characteristic DNA fragments in size. These characteristics of SCCmec element may facilitate the usage of SCCmec in the molecular typing of MRSA strains. In this review, we summarize the structure and function of SCCmec elecments, and discuss the application of SCCmec elements in the molecular typing of MRSA.