How clonal is Staphylococcus aureus?
How clonal is Staphylococcus aureus?
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DOI：
10.1128/jb.185.11.3307-3316.2003
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发表时间：
2003-06-01
影响因子：
3.2
通讯作者：
Day, NPJ
中科院分区：
文献类型：
--
作者：
Feil, EJ;Cooper, JE;Day, NPJ
金黄色葡萄球菌是一种重要的人类病原体，由于耐药性克隆的出现和传播，特别是在医院环境中，金黄色葡萄球菌代表了日益增长的公共卫生负担。尽管如此，关于物种进化和种群生物学的基本问题，特别是关于同源重组的程度和影响，仍然没有答案。我们通过对334株沙门氏菌的多位点序列分型（MLST）特征的序列数据进行分析来解决这些问题。金黄色葡萄球菌，在有限的时间跨度内从明确定义的群体中回收。我们发现从携带者和侵袭性疾病患者分离的菌株之间的多位点基因型的分布没有显着差异，因此，没有证据表明MLST数据，这表明稳定的“核心”基因组内的变异，这种病原体的hypervirullent克隆的存在。在MLST位点的序列变化的检查在克隆多样化表明，点突变引起新的等位基因至少15倍以上的频率比重组。这与自然可转化的脑膜炎奈瑟菌和肺炎链球菌形成对比，其中等位基因通过重组比通过突变更频繁地改变5- 10倍。然而，系统发育分析表明，同源重组确实有助于该物种的长期进化。最后，我们注意到一个显着过量的非同义替换属于同一克隆复合体的分离株之间的比较属于不同的克隆复合体的分离株相比，这表明通过纯化选择去除有害突变可能是相对缓慢的。
Staphylococcus aureus is an important human pathogen and represents a growing public health burden owing to the emergence and spread of antibiotic-resistant clones, particularly within the hospital environment. Despite this, basic questions about the evolution and population biology of the species, particularly with regard to the extent and impact of homologous recombination, remain unanswered. We address these issues through an analysis of sequence data obtained from the characterization by multilocus sequence typing (MLST) of 334 isolates of S. aureus, recovered from a well-defined population, over a limited time span. We find no significant differences in the distribution of multilocus genotypes between strains isolated from carriers and those from patients with invasive disease; there is, therefore, no evidence from MLST data, which index variation within the stable "core" genome, for the existence of hypervirullent clones of this pathogen. Examination of the sequence changes at MLST loci during clonal diversification shows that point mutations give rise to new alleles at least 15-fold more frequently than does recombination. This contrasts with the naturally transformable species Neisseria meningitidis and Streptococcus pneumoniae, in which alleles change between 5- and 10-fold more frequently by recombination than by mutation. However, phylogenetic analysis suggests that homologous recombination does contribute toward the evolution of this species over the long term. Finally, we note a striking excess of nonsynonymous substitutions in comparisons between isolates belonging to the same clonal complex compared to isolates belonging to different clonal complexes, suggesting that the removal of deleterious mutations by purifying selection may be relatively slow.