Analysis of the genetic variability of virulence-related loci in epidemic clones of methicillin-resistant Staphylococcus aureus
Analysis of the genetic variability of virulence-related loci in epidemic clones of methicillin-resistant Staphylococcus aureus
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DOI：
10.1128/aac.49.1.366-379.2005
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发表时间：
2005-01-01
影响因子：
4.9
通讯作者：
de Lencastre, H
中科院分区：
文献类型：
--
作者：
Gomes, AR;Vinga, S;de Lencastre, H
利用脉冲场凝胶电泳结合多位点序列分型（MLST）和葡萄球菌盒染色体mec分型，将耐甲氧西林金黄色葡萄球菌（MRSA）分离株划分为主要的流行克隆型。我们的目的是研究毒力相关因子潜在多态结构域的遗传变异是否可以在不同的流行MRSA克隆中提供另一种水平的分化。对20世纪60年代流行克隆代表菌株和遗传相关的甲氧西林敏感金黄色葡萄球菌分离株进行测序的靶区包括ctfA和clfB的R结构域；fnbA和fnbB的D、W、M区；agr操纵子有三个区域。序列变异范围从RNAIII和agr间启动子区域等非常保守的区域到elf基因高度多态性的R区域。根据cff R结构域的3′区序列，可将其分为6种主要的序列类型。在氨基酸水平上，fnb序列也有6种序列类型。从进化的角度来看，有趣的是，这组菌株的3' elf r结构域序列和fnb序列的一小段DNA延伸与MLST的结果一致。特别是clfB r -结构域序列具有较高的区分能力，其所区分的类型与其他分子分型方法所获得的类型一致，具有用于金黄色葡萄球菌分型的潜力。clf和fnb基因中的克隆和菌株特异性序列基序可能是DNA阵列分型方法的有用补充。
Methicillin-resistant Staphylococcus aureus (MRSA) isolates have previously been classified into major epidemic clonal types by pulsed-field gel electrophoresis in combination with multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec typing. We aimed to investigate whether genetic variability in potentially polymorphic domains of virulence-related factors could provide another level of differentiation in a diverse collection of epidemic MRSA clones. The target regions of strains representative of epidemic clones and genetically related methicillin-susceptible S. aureus isolates from the 1960s that were sequenced included the R domains of ctfA and clfB; the D, W, and M regions of fnbA and fnbB; and three regions in the agr operon. Sequence variation ranged from very conserved regions, such as those for RNAIII and the agr interpromoter region, to the highly polymorphic R regions of the elf genes. The sequences of the cff R domains could be grouped into six major sequence types on the basis of the sequences in their 3' regions. Six sequence types were also observed for the fnb sequences at the amino acid level. From an evolutionary point of view, it was interesting that a small DNA stretch at the 3' elf R-domain sequence and the fnb sequences agreed with the results of MLST for this set of strains. In particular, clfB R-domain sequences, which had a high discriminatory capacity and with which the types distinguished were congruent with those obtained by other molecular typing methods, have potential for use for the typing of S. aureus. Clone- and strain-specific sequence motifs in the clf and fnb genes may represent useful additions to a typing methodology with a DNA array.