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Resistome and plasmidome genomic features of mcr-1.1-harboring Escherichia coli: a One Health approach

Gabriela Simões de Oliveira1,2,3, Silvia Adriana Mayer Lentz4, Camila Zanfelice Müller3,5

  • 1Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, 90035-903, Brazil.

Journal of Applied Microbiology
|January 14, 2025
PubMed
Abstract

Insights

The colistin resistance gene mcr-1.1 is spreading in Brazil through the IncX4 plasmid in Escherichia coli. Pig farming is a key reservoir for this multidrug resistance, with mcr-1.1 co-occurring with mcr-3.12.

Area of Science:

  • Microbiology
  • Genomics
  • Antimicrobial Resistance

Background:

  • Colistin is a crucial last-resort antibiotic.
  • The emergence of colistin resistance, particularly the mcr-1.1 gene, poses a significant public health threat.
  • Understanding the transmission dynamics of mcr-1.1 is essential for effective control strategies.

Purpose of the Study:

  • To investigate the phenotypic and genotypic characteristics of mcr-1.1-positive Escherichia coli from diverse sources in Southern Brazil.
  • To identify the mobile genetic elements and resistome associated with mcr-1.1 dissemination.
  • To determine the role of different hosts and environments in the spread of mcr-1.1.

Main Methods:

  • Antimicrobial susceptibility testing of 22 mcr-1.1-harboring E. coli isolates.
  • Whole genome sequencing for comprehensive resistome and plasmid analysis.
  • Characterization of sequence types and mobile genetic elements.

Main Results:

  • All 22 E. coli isolates carried the mcr-1.1 gene, predominantly on highly similar IncX4 plasmids.
  • Multiple resistance genes were identified across the isolates.
  • One isolate from a farm environment exhibited co-occurrence of mcr-1.1 and mcr-3.12 genes.

Conclusions:

  • Horizontal transfer of the IncX4 plasmid is the primary mechanism for mcr-1.1 spread in Brazilian E. coli.
  • Pig farming environments serve as significant reservoirs for colistin resistance, evidenced by the co-occurrence of mcr-1.1 and mcr-3.12.
Keywords:
E. coliIncX4 plasmidOne Healthmcrplasmidomeresistome

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