Zong Zhiyong, Ginn Andrew N, Dobiasova Hana, Iredell Jonathan R, Partridge Sally R
Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia; Department of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia.
Plasmid. 2015 Jul;80:118-26. doi: 10.1016/j.plasmid.2015.04.007. Epub 2015 Apr 27.
The bla(CTX-M-15) gene, encoding the globally dominant CTX-M-15 extended-spectrum β-lactamase, has generally been found in a 2.971-kb ISEcp1-bla(CTX-M-15)-orf477Δ transposition unit, with ISEcp1 providing a promoter. In available IncF plasmid sequences from Escherichia coli, this transposition unit interrupts a truncated copy of transposon Tn2 that lies within larger multiresistance regions. In E. coli, bla(CTX-M-15) is also commonly associated with IncI1 plasmids and here three such plasmids from E. coli clinical isolates from western Sydney 2006-2007 have been sequenced. The plasmid backbones are organised similarly to those of other IncI1 plasmids, but have insertions and/or deletions and sequence differences. Each plasmid also has a different insertion carrying bla(CTX-M-15). pJIE113 (IncI1 sequence type ST31) is almost identical to plasmids isolated from the 2011 E. coli O104:H4 outbreak in Europe, where the typical bla(CTX-M-15) transposition unit interrupts a complete Tn2 inserted directly in the plasmid backbone. In the novel plasmid pJIE139 (ST88), ISEcp1-blaC(TX-M-15)-orf477Δ lies within a Tn2/3 hybrid transposon. Homologous recombination could explain movement of ISEcp1-bla(CTX-M-15)-orf477Δ between copies of Tn2 on IncF and IncI1 plasmids and generation of the Tn2/3 hybrid. pJIE174 (ST37) is almost identical to pESBL-12 from the Netherlands and in these plasmids bla(CTX-M-15) is flanked by two copies of IS26 that truncate the transposition unit within a larger region bounded by the ends of Tn2. bla(CTX-M-15) and the associated ISEcp1-derived promoter may be able to move from this structure by the actions of IS26, independently of both ISEcp1 and Tn2.
编码全球占主导地位的CTX-M-15超广谱β-内酰胺酶的bla(CTX-M-15)基因，通常存在于一个2.971 kb的ISEcp1-bla(CTX-M-15)-orf477Δ转座单元中，其中ISEcp1提供启动子。在来自大肠杆菌的可用IncF质粒序列中，这个转座单元打断了位于更大的多抗性区域内的转座子Tn2的一个截短拷贝。在大肠杆菌中，bla(CTX-M-15)也通常与IncI1质粒相关，这里对2006 - 2007年从悉尼西部的大肠杆菌临床分离株中获得的三个此类质粒进行了测序。这些质粒骨架的组织方式与其他IncI1质粒相似，但存在插入和/或缺失以及序列差异。每个质粒还带有不同的携带bla(CTX-M-15)的插入片段。pJIE113（IncI1序列类型ST31）与2011年欧洲大肠杆菌O104:H4疫情中分离出的质粒几乎相同，在那里典型的bla(CTX-M-15)转座单元打断了直接插入质粒骨架的完整Tn2。在新型质粒pJIE139（ST88）中，ISEcp1-blaC(TX-M-15)-orf477Δ位于一个Tn2/3杂交转座子内。同源重组可以解释ISEcp1-bla(CTX-M-15)-orf477Δ在IncF和IncI1质粒上的Tn2拷贝之间的移动以及Tn2/3杂交体的产生。pJIE174（ST37）与来自荷兰的pESBL-12几乎相同，在这些质粒中，bla(CTX-M-15)两侧是两个IS26拷贝，它们在由Tn2末端界定的更大区域内截短了转座单元。bla(CTX-M-15)和相关的ISEcp1衍生启动子可能能够通过IS26的作用从这个结构中移动，独立于ISEcp1和Tn2。
