Identification of Novel Conjugative Plasmids with Multiple Copies of fosB that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.
Identification of Novel Conjugative Plasmids with Multiple Copies of fosB that Confer High-Level Fosfomycin Resistance to Vancomycin-Resistant Enterococci.
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具有多个 fosB 拷贝的新型接合质粒的鉴定，该质粒赋予耐万古霉素肠球菌高水平的磷霉素抗性
DOI：
10.3389/fmicb.2017.01541
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发表时间：
2017
影响因子：
5.2
通讯作者：
Yu Y
中科院分区：
文献类型：
--
作者：
Sun L;Zhang P;Qu T;Chen Y;Hua X;Shi K;Yu Y
为了进一步表征19种耐万古霉素肠球菌携带磷的质粒，我们通过单分子实时测序获得了屎肠球菌（pEMA120）和鸟肠球菌（pEA19081）携带磷和钒的质粒的完整序列。我们发现这两个质粒基本相同（99.99%核苷酸序列相同），证明了种间传播的可能性。质粒的比较分析表明，pEMA120的主干与共轭的磷阴性粪肠质粒pZB18相似度达99%。在pEMA120的转移区有一个谱线中断，而pZB18的谱线完整。pEMA120和pZB18之间的转移频率差异表明，traE的中断可能会影响共轭转移。在pEMA120的不同位置发现了与tnpA基因相连的fosB基因的两个拷贝，形成了一个isl3样转座子，这在以前没有报道过。通过反相PCR证实这两个携带磷的转座子形成环状中间体。BsaI酶切的质粒DNA在fosB序列内有限制性内切位点，杂交结果表明每个质粒存在多个fosB拷贝是常见的。qRT-PCR结果显示，fosB基因的总拷贝数与磷霉素mic或不同转偶联物中磷霉素亚mic的生长速率无关。从敏感性测试来看，无论拷贝数如何，fosB基因都具有高磷霉素mic，范围为16384至65536 μg/ml。在VRE中携带两个fosB拷贝的质粒的第一个完整核苷酸序列表明，fosB基因可以通过ISL3家族转座酶TnpA转移到质粒的多个位点上，可能以环状中间体的形式转移，导致VRE中高磷霉素耐药性的传播。
To further characterize the fosB-carrying plasmids of 19 vancomycin-resistant enterococci, the complete sequences of the fosB- and vanA-containing plasmids of Enterococcus faecium (pEMA120) and E. avium (pEA19081) were obtained by single-molecule, real-time sequencing. We found that these two plasmids are essentially identical (99.99% nucleotide sequence identity), which proved the possibility of interspecies transmission. Comparative analysis of the plasmids revealed that the backbone of pEMA120 is 99% similar to a conjugative fosB-negative E. faecium plasmid, pZB18. There is a traE disrupted in the transfer region of pEMA120, in comparison to pZB18 with an intact traE. The difference of their transfer frequencies between pEMA120 and pZB18 suggests this interruption of traE might affect conjugative transfer. Two copies of the fosB gene linked to a tnpA gene, forming an ISL3-like transposon, were found at separate locations within pEMA120, which had not been reported previously. These two fosB-carrying transposons were confirmed to form circular intermediates by inverse PCR. The hybridization of plasmid DNA digested by BsaI, having restriction site within the fosB sequence, demonstrated that the presence of multiple copies of fosB per plasmid is common. The total copy number of the fosB gene as revealed by qRT-PCR did not correlate with fosfomycin MICs or growth rates at sub-MICs of fosfomycin in different transconjugants. From susceptibility tests, the fosB gene, regardless of the copy number, conferred high fosfomycin MICs that ranged from 16384 to 65536 μg/ml. This first complete nucleotide sequence of a plasmid carrying two copies of fosB in VRE suggests that the fosB gene can transfer to multiple loci of plasmids by the ISL3 family transposase TnpA, possibly in the form of circular intermediates, leading to the dissemination of high fosfomycin resistance in VRE.
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影响因子：
3.2
作者：
Cao, M;Bernat, BA;Helmann, JD
通讯作者：
Helmann, JD
影响因子：
3.2
作者：
Christie-Oleza, J. A.;Lanfranconi, M. P.;Bosch, R.
通讯作者：
Bosch, R.
影响因子：
3.2
作者：
Lam, Margaret M. C.;Seemann, Torsten;Stinear, Timothy P.
通讯作者：
Stinear, Timothy P.
影响因子：
14.9
作者：
Grant JR;Stothard P
通讯作者：
Stothard P
影响因子：
4.9
作者：
Descourouez, Jillian L.;Jorgenson, Margaret R.;Rose, Warren E.
通讯作者：
Rose, Warren E.