Molecular typing of selected Enterococcus faecalis isolates:: Pilot study using multilocus sequence typing and pulsed-field gel electrophoresis
Molecular typing of selected Enterococcus faecalis isolates:: Pilot study using multilocus sequence typing and pulsed-field gel electrophoresis
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DOI：
10.1128/jcm.40.3.868-876.2002
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发表时间：
2002-03-01
影响因子：
9.4
通讯作者：
Murray, BE
中科院分区：
文献类型：
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作者：
Nallapareddy, SR;Duh, RW;Murray, BE
本研究比较了最近发展的多位点序列分型（MLST）方法和一种成熟的分子分型技术——脉冲场凝胶电泳（PFGE），用于区分粪肠球菌分离物的亚种。我们对22株粪肠球菌分离株的3个粪肠球菌抗原编码基因（ace，编码胶原蛋白和层粘连蛋白；efaAg，编码心内膜炎抗原；saL4，编码细胞壁相关抗原）和1个持家基因（pyrC）的基因内区域进行了测序，这些分离株的选择主要是因为它们的时间和地理多样性，但也包括一些爆发分离株。对这4个基因的多态区进行MLST分析，鉴定出13种不同的序列类型（st），具有不同的等位基因谱；4个基因片段合成的序列在22株分离物中具有98.3% ~ 100%的同源性。我们还发现，来自ace和saL4两个序列的等位基因谱足以区分本研究的所有13个STs。13个STs对应12种不同的PFGE类型，其中一个先前指定的PFGE克隆（一种广泛存在于美国的β -内酰胺酶产生分离物的克隆）被划分为两个高度相关的STs，这两个STs在2,894个碱基中有2个不同，都在同一等位基因上。MLST还证实了其他两个PFGE克隆群之间的克隆关系，包括万古霉素耐药菌株。因此，这项具有代表性的粪肠球菌分离株的初步研究表明，与PFGE类似，基于序列的分型方法除了识别暴发分离株外，还可用于将粪肠球菌分离株区分到亚种水平。
The present study compared the recently developed multilocus sequence typing (MLST) approach with a well-established molecular typing technique, pulsed-field gel electrophoresis (PFGE), for subspecies differentiation of Enterococcus faecalis isolates. We sequenced intragenic regions of three E. faecalis antigen-encoding genes (ace, encoding a collagen and laminin adhesin; efaAg encoding an endocarditis antigen; and saL4, encoding a cell wall associated antigen) and one housekeeping gene (pyrC) of 22 E. faecalis isolates chosen largely for their temporal and geographical diversity, but also including some outbreak isolates. MLST analysis of polymorphic regions of these four genes identified 13 distinct sequence types (STs) with different allelic profiles; the composite sequences generated from the four sequenced gene fragments of individual isolates showed 98.3 to 100% identity among the 22 isolates. We also found that the allelic profiles from two sequences, ace and saL4, were sufficient to distinguish all 13 STs of this study. The 13 STs corresponded to 12 different PFGE types, with one previously designated PFGE clone (a widespread U.S. clone of beta-lactamase-producing isolates) being classified into two highly related STs which differed at 2 of 2,894 bases, both in the same allele. MLST also confirmed the clonal relationships among the isolates of two other PFGE clonal groups, including vancomycin resistant isolates. Thus, this pilot study with representative E.faecalis isolates suggests that, similar to PFGE, the sequence-based typing method may be useful for differentiating isolates of E.faecalis to the subspecies level in addition to identifying outbreak isolates.