title: Characterization of epidemic IncI1-Iγ plasmids harboring ambler class A and C genes in Escherichia coli and Salmonella enterica from animals and humans.
abstract: The aim of the study was to identify the plasmid-encoded factors contributing to the emergence and spread of epidemic IncI1-Iγ plasmids obtained from Escherichia coli and Salmonella enterica isolates from animal and human reservoirs. For this, 251 IncI1-Iγ plasmids carrying various extended-spectrum β-lactamase (ESBL) or AmpC β-lactamase genes were compared using plasmid multilocus sequence typing (pMLST). Thirty-two of these plasmids belonging to different pMLST types were sequenced using Roche 454 and Illumina platforms. Epidemic IncI1-Iγ plasmids could be assigned to various dominant clades, whereas rarely detected plasmids clustered together as a distinct clade. Similar phylogenetic trees were obtained using only the plasmid backbone sequences, showing that the differences observed between the plasmids belonging to distinct clades resulted mainly from differences between their backbone sequences. Plasmids belonging to the various clades differed particularly in the presence/absence of genes encoding partitioning and addiction systems, which contribute to stable inheritance during cell division and plasmid maintenance. Despite this, plasmids belonging to the various phylogenetic clades also showed marked resistance gene associations, indicating the circulation of successful plasmid-gene combinations. The variation in traY and excA genes found in IncI1-Iγ plasmids is conserved within pMLST sequence types and plays a role in incompatibility, although functional study is needed to elucidate the role of these genes in plasmid epidemiology.
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands hilde.smith@wur.nl dik.mevius@wur.nl.
authors.forename: Hilde
authors.initials: H
authors.lastname: Smith
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands.
authors.forename: Alex
authors.initials: A
authors.lastname: Bossers
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Harders
authors.affiliation: Animal and Plant Health Agency, Weybridge, United Kingdom.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wu
authors.affiliation: Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, Public Health England, Colindale, London, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, Neustadt-Mariensee, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwarz
authors.affiliation: Federal Institute for Risk Assessment, Berlin, Germany.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Guerra
authors.affiliation: Federal Institute for Risk Assessment, Berlin, Germany Microbiology Department, Hospital Universitario Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Rodríguez
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands.
authors.forename: Alieda
authors.initials: A
authors.lastname: van Essen-Zandbergen
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands.
authors.forename: Michael
authors.initials: M
authors.lastname: Brouwer
authors.affiliation: Central Veterinary Institute (CVI) part of Wageningen University and Research Centre (WUR), Lelystad, The Netherlands Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands hilde.smith@wur.nl dik.mevius@wur.nl.
authors.forename: Dik
authors.initials: D
authors.lastname: Mevius
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D006801:Humans; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics*; D019779:Salmonella enterica / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases