Australian Collaborating Centre for Enterococcus and Sdtaphylococcus Species (ACCESS) Typing and Research, PathWest Laboratory Medicine-Western Australia, Royal Perth Hospital, Western Australia, Australia.
PLoS One. 2012;7(8):e43037. doi: 10.1371/journal.pone.0043037. Epub 2012 Aug 10.
In Australia the PVL-positive ST93-IV [2B], colloquially known as "Queensland CA-MRSA" has become the dominant CA-MRSA clone. First described in the early 2000s, ST93-IV [2B] is associated with skin and severe invasive infections including necrotizing pneumonia. A singleton by multilocus sequence typing (MLST) eBURST analysis ST93 is distinct from other S. aureus clones. To determine if the increased prevalence of ST93-IV [2B] is due to the widespread transmission of a single strain of ST93-IV [2B] the genetic relatedness of 58 S. aureus ST93 isolated throughout Australia over an extended period were studied in detail using a variety of molecular methods including pulsed-field gel electrophoresis, spa typing, MLST, microarray DNA, SCCmec typing and dru typing. Identification of the phage harbouring the lukS-PV/lukF-PV Panton Valentine leucocidin genes, detection of allelic variations in lukS-PV/lukF-PV, and quantification of LukF-PV expression was also performed. Although ST93-IV [2B] is known to have an apparent enhanced clinical virulence, the isolates harboured few known virulence determinants. All PVL-positive isolates carried the PVL-encoding phage ΦSa2USA and the lukS-PV/lukF-PV genes had the same R variant SNP profile. The isolates produced similar expression levels of LukF-PV. Although multiple rearrangements of the spa sequence have occurred, the core genome in ST93 is very stable. The emergence of ST93-MRSA is due to independent acquisitions of different dru-defined type IV and type V SCCmec elements in several spa-defined ST93-MSSA backgrounds. Rearrangement of the spa sequence in ST93-MRSA has subsequently occurred in some of these strains. Although multiple ST93-MRSA strains were characterised, little genetic diversity was identified for most isolates, with PVL-positive ST93-IVa [2B]-t202-dt10 predominant across Australia. Whether ST93-IVa [2B] t202-dt10 arose from one PVL-positive ST93-MSSA-t202, or by independent acquisitions of SCCmec-IVa [2B]-dt10 into multiple PVL-positive ST93-MSSA-t202 strains is not known.
在澳大利亚，PVL 阳性 ST93-IV [2B]，俗称“昆士兰 CA-MRSA”，已成为主要的 CA-MRSA 克隆。该克隆于 21 世纪初首次描述，与皮肤和严重侵袭性感染有关，包括坏死性肺炎。通过多位点序列分型 (MLST) eBURST 分析，单峰 ST93 与其他金黄色葡萄球菌克隆不同。为了确定 ST93-IV [2B] 的高流行率是否是由于 ST93-IV [2B] 的单一菌株广泛传播所致，我们使用多种分子方法详细研究了在澳大利亚各地分离的 58 株 ST93 金黄色葡萄球菌的遗传相关性，包括脉冲场凝胶电泳、spa 分型、MLST、微阵列 DNA、SCCmec 分型和 dru 分型。还鉴定了携带 lukS-PV/lukF-PV 杀白细胞素基因的噬菌体，检测了 lukS-PV/lukF-PV 中的等位基因变异，并定量了 LukF-PV 的表达。虽然已知 ST93-IV [2B] 具有明显增强的临床毒力，但这些分离株携带的已知毒力决定因素很少。所有 PVL 阳性分离株均携带编码 PVL 的噬菌体 ΦSa2USA，并且 lukS-PV/lukF-PV 基因具有相同的 R 变体 SNP 谱。分离株产生相似水平的 LukF-PV。尽管 spa 序列发生了多次重排，但 ST93 的核心基因组非常稳定。ST93-MRSA 的出现是由于在几个 spa 定义的 ST93-MSSA 背景下独立获得了不同的 dru 定义的 IV 型和 V 型 SCCmec 元件。随后在一些这些菌株中发生了 spa 序列的重排。尽管对多个 ST93-MRSA 菌株进行了特征描述，但大多数分离株的遗传多样性很少，澳大利亚各地主要是 PVL 阳性 ST93-IVa [2B]-t202-dt10。PVL 阳性 ST93-IVa [2B] t202-dt10 是否源自一个 PVL 阳性 ST93-MSSA-t202，还是通过独立获得 SCCmec-IVa [2B]-dt10 进入多个 PVL 阳性 ST93-MSSA-t202 菌株，目前尚不清楚。
