Whole genome sequencing of diverse Shiga toxin-producing and non-producing Escherichia coli strains reveals a variety of virulence and novel antibiotic resistance plasmids

•Many virulence and resistance genes in pathogenic E. coli are carried on plasmids.•We sequenced plasmids from 26 Shiga toxin-producing and non-producing E. coli strains.•We identified 39 plasmids that carried various virulence and putative virulence genes.•We identified 8 plasmids that carried resistance to various antibiotics and some also had resistance genes for heavy metals.

The genomes of a diverse set of Escherichia coli, including many Shiga toxin-producing strains of various serotypes were determined. A total of 39 plasmids were identified among these strains, and many carried virulence or putative virulence genes of Shiga toxin-producing E. coli strains, virulence genes for other pathogenic E. coli groups, and some had combinations of these genes. Among the novel plasmids identified were eight that carried resistance genes to aminoglycosides, carbapenems, penicillins, cephalosporins, chloramphenicol, dihydrofolate reductase inhibitors, sulfonamides, tetracyclines and resistance to heavy metals. Two of the plasmids carried six of these resistance genes and two novel IncHI2 plasmids were also identified. The results of this study showed that plasmids carrying diverse resistance and virulence genes of various pathogenic E. coli groups can be found in E. coli strains and serotypes regardless of the isolate's source and therefore, is consistent with the premise that these mobile elements carrying these traits may be broadly disseminated among E. coli.