Fundamental parameters governing the transmission of conjugative plasmids

Because their ability to spread infectiously, conjugative plasmids represent a major route for the propagation of antibiotic resistances. In the wild, there are hundreds of different plasmids, but their distribution, prevalence and host range are extremely variable. To understand the reasons behind these ecological differences, we need to obtain precise models for plasmid transmission dynamics. Here, we show that the dynamics of plasmid transmission follow a simple ecological model known as Hollings Type II Functional Response. Plasmid transmission dynamics can be faithfully captured using two parameters: the searching rate (the pace at which a donor bacterium encounters a suitable recipient) and the handling time (the time required for a donor to transfer the plasmid). By analyzing the dynamics of different plasmid prototypes, we show that these parameters are characteristic of the plasmid transfer machinery. Quantifying the dynamics of plasmid spread may shed light on the epidemiology of antibiotic resistance genes.