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Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
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Antibiotic resistance correlates with transmission in plasmid evolution
Paul E Turner1, Elizabeth S C P Williams, Chijioke Okeke
1Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520. paul.turner@yale.edu.
Evolution; International Journal of Organic Evolution
|October 30, 2014
Summary
Bacterial plasmid evolution can lead to distinct virulent and avirulent strains, impacting antibiotic resistance and transmission. This study reveals how plasmid changes affect bacterial hosts differently than the plasmids themselves.
Area of Science:
- Microbiology and Molecular Biology
- Evolutionary Biology
- Genetics
Background:
- Conjugative plasmids are mobile genetic elements that can evolve independently of their bacterial hosts.
- Differences in selection pressures can lead to divergent evolutionary trajectories for plasmids and their hosts.
- The Escherichia coli plasmid pB15 possesses antibiotic resistance genes, including tetracycline resistance.
Purpose of the Study:
- To investigate phenotypic correlations among plasmid characters and estimate divergence among plasmid lineages.
- To understand how experimental evolution affects plasmid traits like antibiotic resistance and transmission rates.
- To examine the impact of plasmid evolution on bacterial host phenotypes.
Main Methods:
- Minimum inhibitory concentration (MIC) assays were used to quantify antibiotic resistance levels.
- Experimental evolution of plasmid-bearing Escherichia coli in laboratory settings.
- Phenotypic correlation analyses and preliminary sequence analyses of plasmid DNA.
Main Results:
- Plasmid evolution resulted in two distinct groups: virulent (highly infectious) and avirulent (weakly infectious) plasmids.
- Bacterial hosts showed convergence in phenotypic performance (carbon-source utilization, fitness) despite plasmid divergence.
- Divergence in plasmid conjugation was linked to alterations in a shufflon region, affecting conjugative ability.
Conclusions:
- Plasmid evolution can lead to significant divergence in plasmid traits, independent of host adaptation.
- A tetracycline-resistance transposon insertion likely correlates antibiotic resistance and transmission efficiency in pB15 derivatives.
- Host bacteria may exhibit more conserved phenotypes compared to their evolving plasmids.
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