title: Diversity analysis of commensal porcine Escherichia coli - associations between genotypes and habitat in the porcine gastrointestinal tract.
abstract: Diversity studies of enteric Escherichia coli have relied almost entirely on faecal isolations on the assumption that they are representative of flora found throughout the gastrointestinal tract. The authors have addressed this belief by analysing isolates obtained from the duodenum, ileum, colon and faeces of pigs. E. coli isolates were obtained from eight pigs and characterized using multi-locus enzyme electrophoresis and PCR-based screening for a range of factors thought to be associated with intestinal and extra-intestinal disease. There are four main genetic groups of commensal E. coli (A, B1, B2, D). Group A strains represented 76 % of the isolates from the duodenum, ileum and colon compared to 58 % of the strains isolated from faeces. A nested molecular analysis of variance based on the allozyme and virulence factor screening results showed that differences among individual pigs accounted for 6 % of the observed genetic diversity, whilst 27 % of the genetic variation could be explained by clonal composition differences among gut regions. Finally, the absence of virulence genes in these commensals indicates that they may be suitable as a probiotic consortium, particularly if they also display increased adherence to enterocytes and antagonistic activity against pathogenic strains of E. coli.
authors.affiliation: Center for Advanced Food Research, University of Western Sydney, Hawkesbury Campus, Penrith South DC, NSW 1797, Australia.|Department of Immunology, Elizabeth Macarthur Agriculture Institute, Woodbridge Rd, Menangle, NSW 2568, Sydney, Australia.
authors.forename: Sameer M
authors.initials: SM
authors.lastname: Dixit
authors.affiliation: School of Botany and Zoology, Australia National University, Canberra, ACT 0200, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Gordon
authors.affiliation: Department of Immunology, Elizabeth Macarthur Agriculture Institute, Woodbridge Rd, Menangle, NSW 2568, Sydney, Australia.
authors.forename: Xi-Yang
authors.initials: XY
authors.lastname: Wu
authors.affiliation: Department of Immunology, Elizabeth Macarthur Agriculture Institute, Woodbridge Rd, Menangle, NSW 2568, Sydney, Australia.
authors.forename: Toni
authors.initials: T
authors.lastname: Chapman
authors.affiliation: Center for Advanced Food Research, University of Western Sydney, Hawkesbury Campus, Penrith South DC, NSW 1797, Australia.
authors.forename: Kaila
authors.initials: K
authors.lastname: Kailasapathy
authors.affiliation: Department of Immunology, Elizabeth Macarthur Agriculture Institute, Woodbridge Rd, Menangle, NSW 2568, Sydney, Australia.
authors.forename: James J-C
authors.initials: JJ
authors.lastname: Chin
mesh_terms: D000818:Animals; D004064:Digestive System / Q000382:microbiology*; D017753:Ecosystem; D004586:Electrophoresis / Q000379:methods; D004798:Enzymes / Q000032:analysis; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D005838:Genotype; D016133:Polymerase Chain Reaction; D013552:Swine / Q000382:microbiology*; D037521:Virulence Factors / Q000032:analysis / Q000235:genetics
chemical_list: D004798:Enzymes; D029968:Escherichia coli Proteins; D037521:Virulence Factors