Tandem 3: Evolution and spread of plasmid-borne antibiotic resistance

Background - Plasmids are genetic elements that colonize prokaryotic cells where they replicate independently of the chromosome. They are considered to be a major driving force in prokaryotic ecology and evolution as they can be transferred between cells, making them potent agents of lateral gene transfer. Many plasmids encode for antibiotic resistance genes and this enables the spread of antibiotic resistance throughout bacterial populations. This tandem explores the contribution of plasmids to the evolution of antibiotic-resistant bacteria in the context of food-related microbes. Antibiotics are used at large scale in agricultural food production, leading to the selection of resistant bacteria. Antibiotic resistant bacteria have the potential to establish within the human population, for example through direct contact with farm animals, manure used in fields, or contaminated food. Plasmids encoding for these resistance genes may be transferred to the human commensal flora, even if the food-associated bacteria are present in the human body only transiently. Surprisingly, the food dissemination route to the reservoir of resistance genes is still largely unexplored. Such information may help to understand the origin of specific resistance processes within human pathogens and possibly point to novel targets for intervention.

Overall objectives

  • Characterize the evolution, spread, and persistence of resistance plasmids in the food production chain with a particular focus on bacteria from salad as a model.
  • Assess how DNA acquisition during plasmid evolution contributes to the spread of antibiotic resistance genes and also the drug-resistant bacteria in food systems and beyond.
  • Develop mathematical models to identify selective conditions favoring the spread of plasmid mediated resistance and to investigate how plasmids persist in bacterial populations over evolutionary time-scales.

Doctoral project 3.1: Plasmid evolution in the food industry

Specific aims

  • Characterize the persistence mechanisms of plasmids encoding antibiotic resistance genes, which were found in food bacteria.
  • Research the evolutionary trajectories of plasmid replicon types found in food bacteria.

People working on this project

  • Prof. Dr. Tal Dagan
  • MSc

PI's Homepage: http://www.mikrobio.uni-kiel.de/de/ag-dagan

Doctoral project 3.2: Mathematical modelling of the evolution and spread of plasmid mediated antibiotic resistance

Specific aims

  • Determine the probability of resistance evolution under a set of selective conditions (e.g. drug heterogeneity in time and space).
  • Explore the evolutionary dynamics for various resistance mechanisms (e.g. selfish vs cooperative resistance).
  • Study the coexistence of resistant and protected sensitive cells under cooperative resistance and the consequences for the persistence time of cooperative resistance after removal of the antibiotic.

People working on this project

  • Dr. Hildegard Uecker
  • MSc

PI's Homepage: http://web.evolbio.mpg.de/stochdyn/