A Broad-Host-Range Plasmid Outbreak: Dynamics of IncL/M Plasmids Transferring Carbapenemase Genes

María Getino1, María López-Díaz2, Nicholas Ellaby2

  • 1Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford GU2 7AL, UK.

Insights

Broad-host-range plasmids carrying carbapenemase genes like NDM-1 and OXA-48 spread globally. IncL plasmids with OXA-48 transferred more efficiently than IncM2 plasmids with NDM-1, indicating different pandemic potentials.

Area of Science:

  • Microbiology
  • Genetics
  • Epidemiology

Background:

  • Broad-host-range conjugative plasmids, including IncL/M types, are key drivers in the global dissemination of carbapenemase genes.
  • The emergence of New Delhi metallo-beta-lactamase 1 (NDM-1) and the pandemic spread of OXA-48-like carbapenemases are significant public health concerns.

Purpose of the Study:

  • To compare the transmission potential, conjugation rates, and fitness costs of IncM2 plasmids encoding NDM-1 versus IncL plasmids encoding OXA-48.
  • To assess the host range and permissiveness of different bacterial phylogroups to plasmid acquisition.

Main Methods:

  • Conjugation experiments were performed in vitro and in vivo using various host bacteria to evaluate plasmid transfer rates.
  • Genomic analysis was conducted on uropathogenic Escherichia coli SAP1756 to characterize the plasmid carrying blaNDM-1.
  • Fitness costs associated with plasmid carriage were assessed in different bacterial hosts.

Main Results:

  • Both NDM-1 (IncM2 plasmid) and OXA-48 (IncL plasmid) carrying plasmids successfully transferred between Enterobacterales species.
  • IncL plasmids carrying OXA-48 demonstrated higher transfer rates and lower host fitness burdens compared to IncM2 plasmids carrying NDM-1.
  • Specific Escherichia coli phylogroups showed differential permissiveness to IncM2 plasmid acquisition.

Conclusions:

  • IncM2 plasmids harboring blaNDM-1 represent emergent threats requiring continuous surveillance.
  • Phenotypic analyses of conjugation and fitness are crucial for predicting the pandemic potential of antimicrobial resistance plasmids.
  • Understanding plasmid transmission dynamics is vital for controlling the spread of carbapenemase-producing Enterobacterales.

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