Plasmids and evolutionary rescue by drug resistance

Area of Science:

• Microbiology
• Evolutionary Biology
• Computational Biology

Background:

• Antibiotic resistance is a critical mechanism for bacterial survival against antibiotic threats.
• Resistance can emerge through spontaneous mutations or horizontal gene transfer via plasmids.

Purpose of the Study:

• To determine whether chromosomal or plasmid-borne genes are the more likely source of evolutionary rescue for bacteria.
• To investigate the role of plasmids as vehicles for antibiotic resistance.

Main Methods:

• Stochastic modeling was employed to simulate bacterial population dynamics.
• The models analyzed the conditions under which resistance genes spread via plasmids versus chromosomes.

Main Results:

• Plasmids are not inherently advantageous locations for antibiotic resistance genes.
• Competition between resistant and non-resistant plasmids significantly impacts the spread of resistance.
• The spread of resistant plasmids can be hindered or halted by competing non-resistant plasmids.

Conclusions:

• The evolutionary rescue of bacterial populations by antibiotic resistance is complex and influenced by gene location.
• Competition at the plasmid level is a crucial factor that must be considered in future studies of antibiotic resistance.
• Rethinking the assumed benefits of plasmids for carrying resistance genes is warranted.