title: Escherichia coli strains belonging to phylogenetic group B2 have superior capacity to persist in the intestinal microflora of infants.
abstract: Escherichia coli strains segregate into 4 phylogenetic groups, designated "A," "B1," "B2," and "D." Pathogenic strains belong to group B2 and, to a lesser extent, group D, which more frequently carry virulence-factor genes than do group A strains and group B1 strains. This study investigated whether the capacity of E. coli to persist in the human intestine is related to its phylogenetic type. Resident (n=58) and transient (n=19) commensal E. coli strains isolated during a longitudinal study of 70 Swedish infants and previously tested for virulence-factor-gene carriage were tested for phylogenetic type. Of the strains resident in the intestinal microflora, 60% belonged to group B2, compared with only 21% of the transient strains (P=.004). In logistic regression, group B2 type predicted persistence in the intestinal microflora, independent of carriage of all investigated virulence-factor genes, including genes for P fimbriae (P=.03). Thus, group B2 strains appear to possess yet unidentified traits that enhance their survival in the human intestine.
authors.affiliation: Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden. forough.nowrouzian@microbio.gu.se
authors.forename: Forough L
authors.initials: FL
authors.lastname: Nowrouzian
authors.forename: Agnes E
authors.initials: AE
authors.lastname: Wold
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Adlerberth
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D004926:Escherichia coli / Q000145:classification* / Q000254:growth & development* / Q000302:isolation & purification / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D006967:Hypersensitivity; D007223:Infant; D007231:Infant, Newborn; D007422:Intestines / Q000382:microbiology*; D010802:Phylogeny; D019105:Random Amplified Polymorphic DNA Technique; D011956:Receptors, Cell Surface / Q000235:genetics; D013548:Sweden; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; C423457:ChuA protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; D037521:Virulence Factors; C058769:fimH protein, E coli; D036781:Fimbriae Proteins