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Co-Occurrence of the mcr-1.1 and mcr-3.7 Genes in a Multidrug-Resistant Escherichia coli Isolate from China

Authors Du C, Feng Y, Wang G, Zhang Z, Hu H, Yu Y, Liu J, Qiu L, Liu H, Guo Z, Huang J, Qiu J

Received 22 June 2020

Accepted for publication 19 September 2020

Published 19 October 2020 Volume 2020:13 Pages 3649—3655


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Professor Suresh Antony

Chongtao Du,1,* Yuyang Feng,1,* Guizhen Wang,2 Zhiyuan Zhang,1 Huimin Hu,1 Yu Yu,1 Jiayang Liu,1 Lihao Qiu,1 Hongtao Liu,1 Zhimin Guo,3 Jing Huang,3 Jiazhang Qiu1

1Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, People’s Republic of China; 2College of Food Engineering, Jilin Engineering Normal University, Changchun 130052, People’s Republic of China; 3Department of Clinical Laboratory, The First Hospital of Jilin University, Changchun 130021, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Jiazhang Qiu
College of Veterinary Medicine, Jilin University, No. 5333 Xi’an Road, Changchun 130062, People’s Republic of China
Jing Huang
Department of Clinical Laboratory, The First Hospital of Jilin University, Changchun 130021, People’s Republic of China

Objective: A colistin-resistant Escherichia coli strain isolated from dog feces was characterized in this study.
Methods and Results: A multiplex PCR assay was used to detect the presence of colistin-resistant mcr genes; it was found that E. coli QDFD216 co-harbored the mcr-1 and mcr-3 genes. Whole-genome sequencing and further bioinformatics analysis revealed that E. coli QDFD216 belonged to serotype O176:H11, fimH1311 type and ST132. The resistance genes blaCTX-M-14, mdfA, dfrA3, acrA, acrB, tolc, and sul3 were present in the chromosome. The mcr-1.1 and mcr-3.7 genes were located in two plasmids of different incompatibility groups. mcr-1.1 was carried by a IncX4-type plasmid within an typical IS 26-parA-mcr-1.1-pap2 cassette, while mcr-3.7 was encoded by an IncP1-type plasmid with a genetic structure of TnAs2-mcr-3.7-dgkA-IS 26. No additional antibiotic resistance genes were carried by either plasmid.
Conclusion: This is the first report of an E. coli isolate co-harboring a mcr-1.1-carrying IncX4 plasmid and a mcr-3.7-carrying IncP1 plasmid. The evolution and mechanism of mcr gene co-existence need further study to assess its impact on public health.

Keywords: colistin resistance, whole-genome sequencing, mcr genes, mcr-1, mcr-3

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