IS5 与大肠杆菌临床分离株中不同的 blaCMY-2 基因串联的关联。
Association of IS5 with divergent tandem blaCMY-2 genes in clinical isolates of Escherichia coli.
机构信息
Center for Research in Anti-Infectives and Biotechnology, Creighton University School of Medicine, Creighton University, 2500 California Plaza, Omaha, Nebraska 68127, USA.
出版信息
J Antimicrob Chemother. 2011 Aug;66(8):1734-8. doi: 10.1093/jac/dkr212. Epub 2011 Jun 1.
OBJECTIVE
To characterize a unique tandem bla(CMY-2) gene arrangement found in two non-identical clinical strains of Escherichia coli.
METHODS
Both plasmid and chromosomal DNA were evaluated using PFGE, restriction digest analysis, plasmid profiling and Southern hybridization. bla(CMY-2) gene expression and gene copy number were evaluated by real-time PCR. Susceptibilities to selected β-lactam antibiotics were determined by agar dilution.
RESULTS
A tandem arrangement for bla(CMY-2) was identified in both isolates and was the only arrangement for bla(CMY-2) observed. These isolates had distinct PFGE and plasmid profiles. Each strain exhibited 2-fold higher bla(CMY-2) mRNA expression and up to 8-fold lower β-lactam susceptibility compared with a strain with a single copy of bla(CMY-2).
CONCLUSION
This is the first report of IS5 being associated with tandem bla(CMY-2). IS5 has previously been associated with antibiotic resistance through tandem gene amplification. The unique tandem arrangement provides a mechanism for increased bla(CMY-2) expression.
目的
对在两株非同源大肠埃希菌临床分离株中发现的独特 bla(CMY-2)基因串联排列进行特征分析。
方法
采用 PFGE、限制性消化分析、质粒图谱分析和 Southern 杂交对质粒和染色体 DNA 进行评估。采用实时 PCR 评估 bla(CMY-2)基因表达和基因拷贝数。采用琼脂稀释法测定对所选β-内酰胺类抗生素的敏感性。
结果
在两个分离株中均发现 bla(CMY-2)的串联排列，这是观察到的 bla(CMY-2)的唯一排列。这些分离株具有不同的 PFGE 和质粒图谱。与单个 bla(CMY-2)拷贝的菌株相比，每个菌株的 bla(CMY-2)mRNA 表达增加了 2 倍，而对β-内酰胺类抗生素的敏感性降低了 8 倍。
结论
这是首次报道 IS5 与 bla(CMY-2)串联相关。IS5 先前曾通过串联基因扩增与抗生素耐药性相关。独特的串联排列为 bla(CMY-2)的高表达提供了一种机制。
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