溶血葡萄球菌和藤黄微球菌中葡萄球菌盒式染色体 mec 的分析:新型 ccr 基因复合物的鉴定,带有新鉴定的 ccrA 同种型(ccrA7)。
Analysis of Staphylococcal cassette chromosome mec in Staphylococcus haemolyticus and Staphylococcus sciuri: identification of a novel ccr gene complex with a newly identified ccrA allotype (ccrA7).
机构信息
Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan.
出版信息
Microb Drug Resist. 2011 Jun;17(2):291-7. doi: 10.1089/mdr.2010.0144. Epub 2011 Mar 9.
Methicillin resistance in staphylococci is conferred by the acquisition in its chromosome of the mecA gene, which is located on a mobile genetic element called staphylococcal cassette chromosome mec (SCCmec). Genetic type of SCCmec is defined by combination of mec gene complex class and cassette chromosome recombinase gene (ccr) allotype. In this study, we analyzed genetic diversity of the SCCmec in 11 Staphylococcus haemolyticus strains and a Staphylococcus sciuri strain, which were recently isolated from clinical specimens in Bangladesh. Among these strains, only two S. haemolyticus strains were proved to have the known types of SCCmec, that is, SCCmec V (class C2 mec-ccrC) and VII (class C1 mec-ccrC). Five S. haemolyticus strains were assigned two unique mec-ccr gene complexes combination; that is, class C1 mec-ccrA4B4 (four isolates) and class A mec-ccrC (one isolate). In the remaining four S. haemolyticus strains with class C1 mec, no known ccr allotypes could be detected. A single S. sciuri strain with class A mec complex carried a ccrA gene belonging to a novel allotype designated ccrA7, together with ccrB3. The ccrA7 gene in the S. sciuri strain showed 61.7%-82.7% sequence identity to the ccrA gene sequences published so far, and 75.3% identity to ccrA3, which is a component of the type 3 ccr complex (ccrA3-ccrB3) in methicillin-resistant Staphylococcus aureus. The results of the present study indicated that mec gene complex and ccr genes in coagulase-negative staphylococci are highly divergent, and distinct from those of common methicillin-resistant S. aureus. Identification of the novel ccrA7 allotype combined with ccrB3 suggested an occurrence of recombination between different ccr complexes in nature.
葡萄球菌属的耐甲氧西林现象是由染色体中 mecA 基因的获得引起的,该基因位于一种称为葡萄球菌盒式染色体 mec(SCCmec)的可移动遗传元件上。SCCmec 的遗传类型是通过 mec 基因复合物类和盒式染色体重组酶基因(ccr)同种型的组合来定义的。在这项研究中,我们分析了最近从孟加拉国临床标本中分离出来的 11 株溶血性葡萄球菌和一株松鼠葡萄球菌的 SCCmec 的遗传多样性。在这些菌株中,只有 2 株溶血性葡萄球菌被证实具有已知类型的 SCCmec,即 SCCmec V(C2 mec-ccrC)和 VII(C1 mec-ccrC)。5 株溶血性葡萄球菌被分配到 2 种独特的 mec-ccr 基因复合物组合;即 C1 mec-ccrA4B4(4 株分离株)和 A 类 mec-ccrC(1 株分离株)。在其余 4 株具有 C1 mec 的溶血性葡萄球菌中,无法检测到已知的 ccr 同种型。一株具有 A 类 mec 复合物的松鼠葡萄球菌携带的 ccrA 基因属于一种新的同种型,称为 ccrA7,与 ccrB3 一起。松鼠葡萄球菌株的 ccrA7 基因与迄今为止发表的 ccrA 基因序列具有 61.7%-82.7%的序列同一性,与 ccrA3 具有 75.3%的同一性,ccrA3 是耐甲氧西林金黄色葡萄球菌中 3 型 ccr 复合物(ccrA3-ccrB3)的组成部分。本研究结果表明,凝固酶阴性葡萄球菌的 mec 基因复合物和 ccr 基因高度多样化,与常见的耐甲氧西林金黄色葡萄球菌不同。新型 ccrA7 同种型与 ccrB3 的鉴定表明,不同 ccr 复合物之间在自然界中发生了重组。