Beijing Academy, Beijing 100028, China; State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China.
Int J Antimicrob Agents. 2018 Aug;52(2):210-217. doi: 10.1016/j.ijantimicag.2018.04.012. Epub 2018 Apr 19.
This study proposes a replicon-based scheme for typing IncX plasmids into nine separately clustering subgroups, including IncX1α, IncX1β and IncX2-8. The complete nucleotide sequences of three IncX8 plasmids, namely pT5282-CTXM and p30860-NR from Enterobacter cloacae and p13190-KPC from Klebsiella pneumoniae, were determined and were compared with two other previously sequenced IncX8 plasmids (pCAV1043-58 and pCAV1741-16). These five plasmids possessed conserved IncX8 backbones with limited genetic variation with respect to gene content and organisation, and each of them carried one or three accessory modules that harboured resistance markers and metabolic gene clusters as well as transposons, insertion sequence (IS)-based transposition units and miniature inverted repeat transposable elements (MITEs), indicating that the relatively small IncX8 backbones were able to integrate various foreign genetic contents. The resistance genes bla and bla (β-lactam resistance), bla (carbapenem resistance) and Δbla, and tet(A) (tetracycline resistance) and mph(E) (macrolide resistance) were found in pT5282-CTXM, p13190-KPC and pCAV1741-16, respectively, whilst p30860-NR and pCAV1043-58 carried no resistance genes. The data presented here provide an insight into the diversification and evolution history of IncX8 plasmids.
本研究提出了一种基于复制子的方案，可将 IncX 质粒分为九个独立聚类亚群进行分型，包括 IncX1α、IncX1β 和 IncX2-8。本研究测定了三个 IncX8 质粒（肠杆菌属 cloacae 的 pT5282-CTXM 和 p30860-NR 以及肺炎克雷伯菌的 p13190-KPC）的完整核苷酸序列，并与另外两个已测序的 IncX8 质粒（pCAV1043-58 和 pCAV1741-16）进行了比较。这五个质粒具有保守的 IncX8 骨架，在基因内容和组织方面具有有限的遗传变异，并且每个质粒都携带一个或三个辅助模块，这些模块携带了耐药标记物和代谢基因簇以及转座子、插入序列（IS）-基于转座单元和微型倒置重复可转座元件（MITE），表明相对较小的 IncX8 骨架能够整合各种外来遗传物质。在 pT5282-CTXM、p13190-KPC 和 pCAV1741-16 中发现了 bla 和 bla（β-内酰胺耐药）、bla（碳青霉烯耐药）和 Δbla，以及 tet(A)（四环素耐药）和 mph(E)（大环内酯类耐药）耐药基因，而 p30860-NR 和 pCAV1043-58 则不携带耐药基因。本研究结果为了解 IncX8 质粒的多样化和进化历史提供了新的视角。
