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Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach
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Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach

Published on: December 14, 2019

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The rise and spread of mcr plasmid-mediated polymyxin resistance

Sue C Nang1, Jian Li1, Tony Velkov2

  • 1a Department of Microbiology, Monash Biomedicine Discovery Institute , Monash University , Melbourne , Australia.

Critical Reviews in Microbiology
|May 25, 2019
PubMed

Insights

The spread of plasmid-mediated polymyxin resistance (mcr) genes threatens last-line antibiotic defenses against Gram-negative bacteria. This review analyzes the epidemiology, microbiology, and genomics of this emerging global health threat.

Area of Science:

  • Microbiology
  • Genomics
  • Epidemiology

Background:

  • Polymyxins are crucial last-line antibiotics for treating multidrug-resistant (MDR) Gram-negative bacterial infections.
  • The emergence and global spread of plasmid-mediated polymyxin resistance (mcr) genes pose a significant threat to their clinical utility.
  • The first mcr gene (mcr-1) was identified in 2015, with subsequent reports of various mcr genes (mcr-2 to -7) worldwide.

Purpose of the Study:

  • To review the epidemiological, microbiological, and genomics aspects of mcr-mediated polymyxin resistance.
  • To analyze the current knowledge on the emergence and dissemination of mcr genes.
  • To highlight the implications of mcr genes for global human health.

Main Methods:

  • Literature review encompassing epidemiological data.
  • Microbiological characterization of mcr-carrying isolates.
  • Genomic analysis of mcr genes and their plasmid reservoirs.

Main Results:

  • mcr genes have been detected in numerous Gram-negative bacteria, including *Escherichia coli* and *Klebsiella pneumoniae*, across diverse sources (animals, food, environment, humans) and continents.
  • mcr genes are found on various plasmids, indicating a diverse reservoir.
  • Co-occurrence of mcr genes with genes for extended-spectrum beta-lactamases and carbapenemases is a major concern.

Conclusions:

  • The global dissemination of mcr genes represents a critical threat to polymyxin efficacy.
  • Understanding the epidemiology, microbiology, and genomics of mcr is essential for combating this resistance.
  • Urgent strategies are needed to mitigate the impact of mcr-mediated resistance on public health.
Keywords:
Gram-negative bacteriapolymyxin resistance

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