Novel IS26-mediated hybrid plasmid harbouring tet(X4) in Escherichia coli

Pengcheng Du; Dejun Liu; Huangwei Song; Pei Zhang; Ruichao Li; Yulin Fu; Xiao Liu; Jinli Jia; Xiaodi Li; Séamus Fanning; Yang Wang; Li Bai; Hui Zeng

doi:10.1016/j.jgar.2020.03.018

Novel IS26-mediated hybrid plasmid harbouring tet(X4) in Escherichia coli

J Glob Antimicrob Resist. 2020 Jun:21:162-168. doi: 10.1016/j.jgar.2020.03.018. Epub 2020 Apr 2.

Authors

Pengcheng Du¹, Dejun Liu², Huangwei Song², Pei Zhang³, Ruichao Li⁴, Yulin Fu², Xiao Liu², Jinli Jia⁵, Xiaodi Li⁵, Séamus Fanning⁶, Yang Wang², Li Bai⁷, Hui Zeng⁸

Affiliations

¹ Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, and Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, People's Republic of China.
² Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, People's Republic of China.
³ Key Laboratory of Food Safety Risk Assessment, National Health Commission of the People's Republic of China, China National Center for Food Safety Risk Assessment, Beijing, People's Republic of China.
⁴ Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu Province, People's Republic of China.
⁵ Center for Disease Control and Prevention of Liaocheng, Liaocheng, People's Republic of China.
⁶ Key Laboratory of Food Safety Risk Assessment, National Health Commission of the People's Republic of China, China National Center for Food Safety Risk Assessment, Beijing, People's Republic of China; UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland.
⁷ Key Laboratory of Food Safety Risk Assessment, National Health Commission of the People's Republic of China, China National Center for Food Safety Risk Assessment, Beijing, People's Republic of China. Electronic address: baili@cfsa.net.cn.
⁸ Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, and Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, People's Republic of China. Electronic address: zenghui@ccmu.edu.cn.

PMID: 32247809
DOI: 10.1016/j.jgar.2020.03.018

Abstract

Objectives: As the spread of antimicrobial resistance genes becomes an increasing global threat, improved understanding of genetic structure and transferability of the resistant plasmids becomes more critical. The newly description of several plasmid-mediated tet(X) variant genes, tet(X3), tet(X4) and tet(X5), poses a considerable risk for public health. This study aimed to investigate the recombination event that occurred during the conjugation process of a tet(X4)-bearing plasmid.

Methods: A Tet(X4)-producing Escherichia coli isolate, 2019XSD11, was subjected to susceptibility testing, S1-PFGE and whole genome sequencing. The genetic features of plasmids and the recombination event were analysed by sequence comparison and annotation. We performed electrotransformation assay to further test the transferability of the tet(X4)-bearing plasmid.

Results: A novel type of fusion tet(X4)-bearing plasmid was discovered from the transconjugant, plasmid p2019XSD11-TC2-284 (∼280kbp). The sequence of this plasmid consisted of a hybrid episome of two plasmids p2019XSD11-190 (∼190kbp) harbouring tet(X4) and p2019XSD11-92 (∼92kbp) harbouring bla_CTX-M-55 originated from 2019XSD11. The two plasmids were concatenated by IS26 elements. Analyses of the genetic constitution of the plasmids essential for transmission showed the plasmid p2019XSD11-190 lacked an intact type IV secretion system. Beyond this, the origin of transfer region and relaxase genes in plasmid p2019XSD11-190 had no sequence similarity with those in plasmid p2019XSD11-92.

Conclusions: The fusion of the two plasmids probably formed through IS26 homologous recombination. Such recombination events presumably play an important role in the dissemination of the tet(X4). Molecular surveillance of tet(X) variant genes and genetic structures warrants further investigation to evaluate the underlying public health risk.

Keywords: Co-integration plasmid; Intramolecular restructuring; Tigecycline resistance; tet(X4) gene.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anti-Bacterial Agents* / pharmacology
Escherichia coli* / genetics
Microbial Sensitivity Tests
Plasmids / genetics
Tigecycline

Substances

Anti-Bacterial Agents
Tigecycline