Population structure of a hybrid clonal group of methicillin-resistant Staphylococcus aureus, ST239-MRSA-III.
Population structure of a hybrid clonal group of methicillin-resistant Staphylococcus aureus, ST239-MRSA-III.
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DOI：
10.1371/journal.pone.0008582
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发表时间：
2010-01-05
期刊：
影响因子：
3.7
通讯作者：
Robinson DA
中科院分区：
文献类型：
--
作者：
Smyth DS;McDougal LK;Gran FW;Manoharan A;Enright MC;Song JH;de Lencastre H;Robinson DA
被称为 ST239-MRSA-III 的耐甲氧西林金黄色葡萄球菌 (MRSA) 克隆群因其混合起源以及自 20 世纪 70 年代末以来在全球范围内引起持续的医院流行病而闻名。我们使用 34 年来从 29 个国家收集的 111 个分离株样本，研究了该 MRSA 克隆群的种群结构。使用分型方法和新颖的确定方法评估遗传变异，从所有分离株的 32 个基因座中获得大约 15 kb 的序列。一棵最简约的树，没有同质性，将 28 个单倍型划分为地理相关的进化枝，包括著名的欧洲、亚洲和南美进化枝。据估计，细菌的进化速度比标准估计快约 100 倍，并且这些分离株的最近共同祖先可以追溯到 20 世纪中叶。发现 ST239 系统发育与甲氧西林抗性遗传元件 SCCmec III 型的 ccrB 和 dru 位点之间存在关联，但与多重 PCR 亚型分析工具所针对的元件的辅助成分没有关联。总之，ST239的进化史可以以快速克隆多样化为特征，这留下了地理和时间种群结构的有力证据。 SCCmec III 型在克隆多样化过程中仍与 ST239 染色体保持连锁，但它经历了辅助成分的同质性损失。这些结果为精确鉴定新出现的 ST239 变异提供了一个群体遗传学框架，并要求重新评估用于 SCCmec 亚型分型的标记。
The methicillin-resistant Staphylococcus aureus (MRSA) clonal group known as ST239-MRSA-III is notable for its hybrid origin and for causing sustained hospital epidemics worldwide since the late 1970s. We studied the population structure of this MRSA clonal group using a sample of 111 isolates that were collected over 34 years from 29 countries. Genetic variation was assessed using typing methods and novel ascertainment methods, resulting in approximately 15 kb of sequence from 32 loci for all isolates. A single most parsimonious tree, free of homoplasy, partitioned 28 haplotypes into geographically-associated clades, including prominent European, Asian, and South American clades. The rate of evolution was estimated to be approximately 100× faster than standard estimates for bacteria, and dated the most recent common ancestor of these isolates to the mid-20th century. Associations were discovered between the ST239 phylogeny and the ccrB and dru loci of the methicillin resistance genetic element, SCCmec type III, but not with the accessory components of the element that are targeted by multiplex PCR subtyping tools. In summary, the evolutionary history of ST239 can be characterized by rapid clonal diversification that has left strong evidence of geographic and temporal population structure. SCCmec type III has remained linked to the ST239 chromosome during clonal diversification, but it has undergone homoplasious losses of accessory components. These results provide a population genetics framework for the precise identification of emerging ST239 variants, and invite a re-evaluation of the markers used for subtyping SCCmec.