Conjugation dynamics depend on both the plasmid acquisition cost and the fitness cost

Plasmid conjugation is a major mechanism responsible for the spread of antibiotic resistance. Plasmid fitness costs are known to impact long‐term growth dynamics of microbial populations by providing plasmid‐carrying cells a relative (dis)advantage compared to plasmid‐free counterparts. Separately, plasmid acquisition introduces an immediate, but transient, metabolic perturbation. However, the impact of these short‐term effects on subsequent growth dynamics has not previously been established. Here, we observed that de novo transconjugants grew significantly slower and/or with overall prolonged lag times, compared to lineages that had been replicating for several generations, indicating the presence of a plasmid acquisition cost. These effects were general to diverse incompatibility groups, well‐characterized and clinically captured plasmids, Gram‐negative recipient strains and species, and experimental conditions. Modeling revealed that both fitness and acquisition costs modulate overall conjugation dynamics, validated with previously published data. These results suggest that the hours immediately following conjugation may play a critical role in both short‐ and long‐term plasmid prevalence. This time frame is particularly relevant to microbiomes with high plasmid/strain diversity considered to be hot spots for conjugation. Synopsis Quantification of plasmid conjugation dynamics shows the presence of a plasmid acquisition cost and indicates that the hours immediately following conjugation may be critical in both short and long‐term plasmid prevalence. A novel experimental framework quantifies plasmid acquisition costs independently of fitness effects. The magnitude of the acquisition costs is potentially dictated by the initial energetic burden imposed by the newly acquired plasmid, as well as the host cells’ ability to accommodate that burden in a given environment. Incorporating acquisition effects into a mathematical model of conjugation improves the temporal predictions of long‐term conjugation dynamics. The time window immediately following plasmid acquisition may represent a critical time interval for quantifying conjugation dynamics. Graphical Abstract Quantification of plasmid conjugation dynamics shows the presence of a plasmid acquisition cost and indicates that the hours immediately following conjugation may be critical in both short and long‐term plasmid prevalence.