Genetic basis of chromosomally-encoded mcr-1 gene

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Ruichao Li
  • Hua Yu
  • Kaichao Chen
  • Ning Dong
  • Dachuan Lin
  • Edward Wai-Chi Chan


Original languageEnglish
Pages (from-to)578-585
Journal / PublicationInternational Journal of Antimicrobial Agents
Issue number4
Online published29 Nov 2017
Publication statusPublished - Apr 2018
Externally publishedYes


Compared with plasmid-borne mcr-1, the occurrence of chromosomally-encoded mcr-1 is rare although it has been reported in several cases. This study aimed to investigate the genetic features of chromosomally-encoded mcr-1 among Escherichia coli strains as well as the potential genetic basis governing mobilisation of mcr-1 in bacterial chromosomes. The genome sequences of 16 E. coli strains containing a chromosomal mcr-1 gene were obtained and analysed. Phylogenetic and whole-genome sequencing (WGS) analysis demonstrated that mcr-1 was associated with four major types of genetic arrangements, namely ISApl1mcr1orf, Tn6330, complex Tn6330 and ΔTn6330 in chromosomes of genetically unrelated E. coli strains. The mcr-1-carrying mobile elements were shown to insert into the AT-rich region, which was also the case for ISApl1. Analysis of complete E. coli genome sequences showed that there were multiple copies of ISApl1 present in E. coli chromosomes that also carried mcr-1, whilst all mcr-1-negative chromosomes were absent of any copy of ISApl1, suggesting the strong association of ISApl1 and mcr-1. Insertion of ISApl1 into E. coli chromosomes may be a prerequisite for the insertion of mcr-1-carrying mobile elements. Insertion of mcr-1 into E. coli chromosomes would enable it to become intrinsically resistant, which is expected to become more prevalent. Policy on the prudent use of colistin both in veterinary and clinical settings should be imposed globally to further prevent dissemination of mcr-1 in E. coli and other bacterial pathogens.

Research Area(s)

  • Chromosome, Circular intermediate, Escherichia coli, mcr-1, Tn6330, Transmission

Citation Format(s)

Genetic basis of chromosomally-encoded mcr-1 gene. / Li, Ruichao; Yu, Hua; Xie, Miaomiao; Chen, Kaichao; Dong, Ning; Lin, Dachuan; Chan, Edward Wai-Chi; Chen, Sheng.

In: International Journal of Antimicrobial Agents, Vol. 51, No. 4, 04.2018, p. 578-585.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review