title: Phylogenetic and molecular insights into the evolution of multidrug-resistant porcine enterotoxigenic Escherichia coli in Australia.
abstract: This study investigated the phylogeny and molecular epidemiology of Australian porcine enterotoxigenic Escherichia coli (ETEC) isolates (n=70) by performing multilocus sequence typing (MLST), random amplified polymorphic DNA (RAPD) analysis, virulence gene analysis, plasmid, bacteriocin, integron and antimicrobial resistance gene typing, and antimicrobial susceptibility phenotyping. Isolates of the most commonly observed O serogroup (O149) were highly clonal with a lower frequency of antimicrobial resistance compared with the less common O141 serogroup isolates, which were more genetically diverse and resistant to a greater array of antimicrobials. The O149 and O141 isolates belonged to sequence types (STs) ST100 and ST1260, respectively. A small number of new STs were identified for the least common serogroups, including O157 (ST4245), O138 (ST4244), O139 (ST4246) and O8 (ST4247). A high frequency of plasmid replicons was observed among all ETEC isolates. However, O149 isolates predominantly carried IncFIB, I1, HI1 and FIC, whereas O141 isolates carried a more varied array, including IncI1, FIB, FIC, HI1, I1, Y and, most significantly, A/C. O141 isolates also possessed a greater diversity of bacteriocins, with almost one-half of the isolates carrying colicin E3 (44.4%; 12/27) and E7 (48.1%; 13/27). This study shows that Australian porcine ETEC are distinct from isolates obtained in other parts of the world with respect to the MLST profile and the absence of resistance to critically important antimicrobials, including third-generation cephalosporins and fluoroquinolones.
authors.affiliation: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia; New South Wales Department of Primary Industries, Menangle, New South Wales, Australia; School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia. Electronic address: sam.abraham@adelaide.edu.au.
authors.forename: Sam
authors.initials: S
authors.lastname: Abraham
authors.affiliation: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia.
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Trott
authors.affiliation: New South Wales Department of Primary Industries, Wollongbar, New South Wales, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Jordan
authors.affiliation: Research School of Biology, The Australian National University, Canberra, ACT, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Gordon
authors.affiliation: The University of Queensland, Gatton, Queensland, Australia.
authors.forename: Mitchell D
authors.initials: MD
authors.lastname: Groves
authors.affiliation: OIE Reference Laboratory for Escherichia coli (EcL), Faculté de médecine vétérinaire, University of Montréal, Saint-Hyacinthe, Canada.
authors.forename: John M
authors.initials: JM
authors.lastname: Fairbrother
authors.affiliation: The University of Queensland, Gatton, Queensland, Australia.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Smith
authors.affiliation: School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia.
authors.forename: Ren
authors.initials: R
authors.lastname: Zhang
authors.affiliation: New South Wales Department of Primary Industries, Menangle, New South Wales, Australia.
authors.forename: Toni A
authors.initials: TA
authors.lastname: Chapman
mesh_terms: D000818:Animals; D001315:Australia / Q000453:epidemiology; D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D054307:Enterotoxigenic Escherichia coli / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D005838:Genotype; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D019105:Random Amplified Polymorphic DNA Technique; D065288:Serogroup; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors
keywords: Antimicrobial resistance; Enterotoxigenic Escherichia coli; IncA/C; Plasmids; Porcine; Serogroups