Timing of antibiotic administration determines the spread of plasmid-encoded antibiotic resistance during microbial range expansion

Plasmids are the main vector by which antibiotic resistance is transferred between bacterial cells within surface-associated communities. In this study, we ask whether there is an optimal time to administer antibiotics to minimize plasmid spread in new bacterial genotypes during community expansion across surfaces. We address this question using consortia of Pseudomonas stutzeri strains, where one is an antibiotic resistance-encoding plasmid donor and the other a potential recipient. We allowed the strains to co-expand across a surface and administered antibiotics at different times. We find that plasmid transfer and transconjugant proliferation have unimodal relationships with the timing of antibiotic administration, where they reach maxima at intermediate times. These unimodal relationships result from the interplay between the probabilities of plasmid transfer and loss. Our study provides mechanistic insights into the transfer and proliferation of antibiotic resistance-encoding plasmids within microbial communities and identifies the timing of antibiotic administration as an important determinant. Plasmids are the main vector by which antibiotic resistance is transferred between bacterial cells within surface-associated communities. Here, Ma et al. show that plasmid spread peaks at intermediate antibiotic administration times, when the intermixing of plasmid donors and potential recipients is maximal.

Automated summary

In this study, the researchers used consortia of Pseudomonas stutzeri strains to investigate the optimal timing of antibiotic administration to minimize the spread of antibiotic resistance-encoding plasmids within microbial communities. They found that plasmid transfer and transconjugant proliferation peaked at intermediate antibiotic administration times when the mixing between plasmid donors and potential recipients was maximal.