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

Chongtao Du; Yuyang Feng; Guizhen Wang; Zhiyuan Zhang; Huimin Hu; Yu Yu; Jiayang Liu; Lihao Qiu; Hongtao Liu; Zhimin Guo; Jing Huang; Jiazhang Qiu

doi:10.2147/IDR.S268787

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

Infect Drug Resist. 2020 Oct 19:13:3649-3655. doi: 10.2147/IDR.S268787. eCollection 2020.

Authors

Chongtao Du^#¹, Yuyang Feng^#¹, Guizhen Wang², Zhiyuan Zhang¹, Huimin Hu¹, Yu Yu¹, Jiayang Liu¹, Lihao Qiu¹, Hongtao Liu¹, Zhimin Guo³, Jing Huang³, Jiazhang Qiu¹

Affiliations

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

^# Contributed equally.

Abstract

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 bla _CTX-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 IS26-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-IS26. 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; mcr genes; mcr-1; mcr-3; whole-genome sequencing.