文献类型： 外文期刊

作者： Zhang, Shaqiu ¹ ; Wen, Jinfeng ¹ ; Wang, Yuwei ¹ ; Zhong, Zhijun ¹ ; Wang, Mingshu ¹ ; Jia, Renyong ¹ ; Chen, Shun ¹ ; Liu, Mafeng ¹ ; Zhu, Dekang ¹ ; Zhao, Xinxin ¹ ; Wu, Ying ¹ ; Yang, Qiao ¹ ; Huang, Juan ¹ ; Ou, Xumin ¹ ; Mao, Sai ¹ ; Gao, Qun ¹ ; Sun, Di ¹ ; Tian, Bin ¹ ; Cheng, Anchun ¹ ;

作者机构： 1.Sichuan Agr Univ, Coll Vet Med, Avian Dis Res Ctr, Chengdu 611130, Peoples R China

2.Sichuan Agr Univ, Key Lab Anim Dis & Human Hlth Sichuan Prov, Chengdu 611130, Peoples R China

3.Minist Educ PR China, Engn Res Ctr Southwest Anim Dis Prevent & Control, Chengdu 611130, Peoples R China

4.Mianyang Acad Agr Sci, Mianyang 621023, Peoples R China

关键词： Escherichia coli; tet(X4); horizontal transfer; plasmid; whole-genome sequencing

期刊名称：POULTRY SCIENCE （ 影响因子：4.4； 五年影响因子：4.4 ）

ISSN： 0032-5791

年卷期： 2023 年 102 卷 12 期

页码：

收录情况： SCI

摘要： Tigecycline is considered one of the "last resort antibiotics" for treating complex infections caused by multidrug-resistant (MDR) bacteria, especially for combating clinical resistant strains that produce carbapenemases. However, the tet(X4) gene, which carried by different plasmids can mediate high levels of bacterial resistance to tigecycline, was first reported in 2019. Here, we report the emergence of the plasmid-mediated tet(X4) in avian environment of Sichuan Province. A total of 21 tet(X4)-positive Escherichia coli (E. coli) strains were isolated and identified from avian samples in selected regions, with an isolation rate of 1.6% (21/1,286), and all of them were MDR strains. Multilocus Sequence Typing (MLST) method was used to classify the 21 tet(X4)-positive E. coli into the ST206, ST761, ST155, ST1638, ST542, and ST767 types, which also belong to the 3 phylogenetic subgroups A, B1, and C. Tet(X4) is located on mobile plasmids that can be efficiently and stably propagated. The results of fitness cost experiments showed thattet(X4)-positive plasmids may incur some fitness cost to host bacteria, but different tet(X4)-positive plasmids bring about differential fitness costs. Whole-genome sequencing further confirmed the tet(X4) gene can be located on IncX1-type plasmids and the core genetic structures are ISVsa3-rdmc-tet(X4) or rdmctet(X4)-ISVsa3, the former is a 7 copies tandem repeat structure. In this study, we isolated and identified tet(X4)-positive E. coli from the avian origin in Sichuan, analyzed the mobility of the tet(X4) by conjugational transfer and S1-PFGE, and evaluated the biological characteristics of the tet(X4)-positive plasmid using the results of conjugational frequency, plasmid stability, and fitness costs. Finally, combined with the third-generation whole-genome sequencing analysis, the molecular transmission characteristics of the tet(X4) were preliminarily clarified, providing a scientific basis for guiding veterinary clinical use in this area, as well as risk assessment and prevention of the transfer and spread of tigecy-cline resistant strains or genes.