Complete sequences of IncHI1 plasmids carrying blaCTX-M-1 and qnrS1 in equine Escherichia coli provide new insights into plasmid evolution
Complete sequences of IncHI1 plasmids carrying blaCTX-M-1 and qnrS1 in equine Escherichia coli provide new insights into plasmid evolution
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DOI：
10.1093/jac/dku172
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发表时间：
2014-09-01
影响因子：
5.2
通讯作者：
Carattoli, Alessandra
中科院分区：
文献类型：
--
作者：
Dolejska, Monika;Villa, Laura;Carattoli, Alessandra
目的：为确定捷克共和国马诊所传播的大肠杆菌中携带bla（CTX-M-1）的两种多药耐药IncHI 1质粒的结构，采用454-Genome Sequencer FLX系统对239 kb IncHI 1（pEQ 1）和287 kb IncHI 1/X1（pEQ 2）质粒进行全核苷酸序列测定。结果：pEQ 1和pEQ 2与IncHI 1 2型质粒具有高度的核苷酸同源性。在pEQ骨架中发现了一个新的24 kb模块，其中包含一个参与短链低聚果糖摄取和代谢的操纵子。通过对大肠杆菌生长的研究，证实了pEQ质粒在短链低聚果糖代谢中的作用。大肠杆菌细胞中这些糖的存在。含有blaCTX-M-1基因的模块由截短的大环内酯类耐药簇形成，并如先前在IncI 1和IncN质粒中观察到的那样侧翼为IS 26。IncHI 1质粒经IS 26介导与IncX 1质粒融合后，大小发生改变，获得了喹诺酮类耐药基因qnrS 1。杆菌一个质粒介导的糖代谢元件可以发挥关键作用，应变健身，有助于成功传播和维护这些质粒在肠道菌群的马。
Objectives: To determine the structure of two multidrug-resistant IncHI1 plasmids carrying bla(CTX-M-1) in Escherichia coli isolates disseminated in an equine clinic in the Czech Republic.Methods: A complete nucleotide sequencing of 239 kb IncHI1 (pEQ1) and 287 kb IncHI1/X1 (pEQ2) plasmids was performed using the 454-Genome Sequencer FLX system. The sequences were compared using bioinformatic tools with other sequenced IncHI1 plasmids.Results: A comparative analysis of pEQ1 and pEQ2 identified high nucleotide identity with the IncHI1 type 2 plasmids. A novel 24 kb module containing an operon involved in short-chain fructooligosaccharide uptake and metabolism was found in the pEQ backbones. The role of the pEQ plasmids in the metabolism of short-chain fructooligosaccharides was demonstrated by studying the growth of E. coli cells in the presence of these sugars. The module containing the blaCTX-M-1 gene was formed by a truncated macrolide resistance cluster and flanked by IS26 as previously observed in IncI1 and IncN plasmids. The IncHI1 plasmid changed size and gained the quinolone resistance gene qnrS1 as a result of IS26-mediated fusion with an IncX1 plasmid.Conclusions: Our data highlight the structure and evolution of IncHI1 from equine E. coli. A plasmid-mediated sugar metabolic element could play a key role in strain fitness, contributing to the successful dissemination and maintenance of these plasmids in the intestinal microflora of horses.