BioProject

Plasmids are key vehicles of horizontal gene transfer (HGT), mobilizing antibiotic resistance, virulence, and other traits among bacterial populations. The environmental and genetic forces that drive plasmid transfer (i.e. conjugation) are poorly understood, however, due to the lack of definitive quantification coupled with genomic analysis. Here, we integrate conjugative phenotype with plasmid genotype to provide large scale, quantitative analysis of HGT in widespread and multidrug resistant E. coli pathogens of pressing clinical concern. We find a substantial proportion of clinical E. coli pathogens (≥25%) able to readily spread resistance to the most common classes of antibiotics. Antibiotics of varied mechanism of action had less than a 5-fold effect on conjugation efficiency in general, with one exception displaying 31-fold promotion upon exposure to macrolides and chloramphenicol. In contrast, genome sequencing reveals plasmid incompatibility group strongly correlates (F(6, 53) = 111.6, p < 0.0001, ANOVA) with transfer efficiency that varies over 5 orders of magnitude. Our findings offer new insights into the determinants of plasmid mobility and have implications for the development of treatments that target HGT.