Berglund Carolina, Ito Teruyo, Ikeda Megumi, Ma Xiao Xue, Söderquist Bo, Hiramatsu Keiichi
Department of Clinical Microbiology, Orebro University Hospital, SE-701 85 Orebro, Sweden.
Antimicrob Agents Chemother. 2008 Oct;52(10):3512-6. doi: 10.1128/AAC.00087-08. Epub 2008 Aug 1.
We identified a novel type of staphylococcal cassette chromosome mec (SCCmec) element carried by methicillin-resistant Staphylococcus aureus (MRSA) strain JCSC6082 isolated in Sweden. The SCCmec element was demarcated by characteristic nucleotide sequences at both ends and was integrated at the 3' end of orfX. The element carried a novel combination of a type 5 ccr gene complex and class C1 mec gene complex. The J regions of the element were homologous to those of the SCCmercury element of S. aureus strain 85/2082, with nucleotide identity greater than 99%. However, the novel SCCmec element from JCSC6082 did not carry the mer operon nor Tn554, suggesting that evolution to SCCmec could have been from a common ancestor by acquisition of the class C1 mec gene complex. The novel SCCmec element from JCSC6082 was flanked by a novel SCC-like chromosome cassette (CC6082), which was demarcated by two direct repeats and could be excised from the chromosome independently of the SCCmec element. Our data suggest that novel SCCmec elements can be generated on the staphylococcal chromosome through the recombination between extant SCC elements and mec gene complexes.
我们鉴定出一种新型葡萄球菌盒式染色体mec（SCCmec）元件，它由在瑞典分离出的耐甲氧西林金黄色葡萄球菌（MRSA）菌株JCSC6082携带。该SCCmec元件由两端的特征性核苷酸序列界定，并整合在orfX的3'端。该元件携带了5型ccr基因复合体和C1类mec基因复合体的新组合。该元件的J区域与金黄色葡萄球菌菌株85/2082的SCCmercury元件的J区域同源，核苷酸同一性大于99%。然而，来自JCSC6082的新型SCCmec元件不携带mer操纵子和Tn554，这表明向SCCmec的进化可能是通过获得C1类mec基因复合体从共同祖先演变而来。来自JCSC6082的新型SCCmec元件两侧是一个新型的SCC样染色体盒（CC6082），它由两个直接重复序列界定，并且可以独立于SCCmec元件从染色体上切除。我们的数据表明，新型SCCmec元件可以通过现存SCC元件和mec基因复合体之间的重组在葡萄球菌染色体上产生。
