Berglund Carolina, Ito Teruyo, Ma Xiao Xue, Ikeda Megumi, Watanabe Shinya, Söderquist Bo, Hiramatsu Keiichi
Department of Clinical Microbiology, Orebro University Hospital, Orebro, Sweden.
J Antimicrob Chemother. 2009 Jan;63(1):32-41. doi: 10.1093/jac/dkn435. Epub 2008 Nov 11.
Recent studies have shown a predominance of type IV SCCmec among the methicillin-resistant Staphylococcus aureus (MRSA) isolated in the low endemic areas of Orebro County and the western region of Sweden. However, many of these isolates were not possible to classify as existing subtypes IVa, IVb, IVc or IVd.
We analysed 16 such MRSA isolates by multilocus sequence typing, spa typing, staphylocoagulase (SC) typing and detection of type IVg and IVh SCCmec. MRSA that remained as unknown type IV SCCmec were investigated by long-range PCR covering the J1 region; however, only two isolates were possible to amplify by PCR. The nucleotide sequences of the entire SCCmec of these two MRSA were determined. In addition, isolates that had unknown SC types were investigated by nucleotide sequencing of the coa genes.
Five of 16 isolates were classified as type IVg SCCmec, and four isolates had type IVh SCCmec. Two subtypes of type IV SCCmec shared J1 regions previously identified in other types of SCCmec, types I.2 and II.2. The novel elements were designated as type IVi and IVj SCCmec. In addition, the genetic backgrounds of these Swedish MRSA were diverse and constituted at least nine sequence types and eight SC types, including four new types of SC.
Type IV SCCmec is occurring in heterogeneous clones of MRSA in Sweden, and the majority of the type IV SCCmec were identified in community-acquired MRSA. We describe two novel subtypes of type IV SCCmec with common J1 regions shared by other types of SCCmec, which indicate that J1 regions occurred as primordial SCC.
最近的研究表明，在瑞典厄勒布鲁县低流行地区和瑞典西部地区分离出的耐甲氧西林金黄色葡萄球菌（MRSA）中，IV型葡萄球菌染色体盒式甲氧西林耐药基因（SCCmec）占主导地位。然而，这些分离株中的许多无法归类为现有的IVa、IVb、IVc或IVd亚型。
我们通过多位点序列分型、spa分型、葡萄球菌凝固酶（SC）分型以及检测IVg和IVh型SCCmec，对16株此类MRSA分离株进行了分析。对仍为未知IV型SCCmec的MRSA，通过覆盖J1区域的长程PCR进行研究；然而，只有两株分离株能够通过PCR扩增。测定了这两株MRSA完整SCCmec的核苷酸序列。此外，对SC类型未知的分离株，通过coa基因的核苷酸测序进行研究。
16株分离株中有5株被归类为IVg型SCCmec，4株为IVh型SCCmec。IV型SCCmec的两个亚型共享先前在其他类型SCCmec（I.2型和II.2型）中鉴定出的J1区域。这些新元件被命名为IVi和IVj型SCCmec。此外，这些瑞典MRSA的遗传背景各不相同，至少构成了9种序列类型和8种SC类型，包括4种新的SC类型。
IV型SCCmec存在于瑞典MRSA的异质克隆中，且大多数IV型SCCmec在社区获得性MRSA中被鉴定出来。我们描述了IV型SCCmec的两种新亚型，它们具有与其他类型SCCmec共享的共同J1区域，这表明J1区域作为原始SCC出现。
