title: Identification and distribution of the enterohemorrhagic Escherichia coli factor for adherence (efa1) gene in sorbitol-fermenting Escherichia coli O157: H-.
abstract: Sorbitol-fermenting (SF) Shiga toxin (Stx)-producing Escherichia coli (STEC) O157:H- strains are emerging as causes of hemorrhagic colitis and the hemolytic-uremic syndrome in Europe. Using subtractive hybridization between SF STEC O157:H- strain 493/89 and STEC O157:H7 strain EDL933, three different fragments, of approximately 700 bp in length, were identified. Each demonstrated > 99% homology to genes encoding the enterohemorrhagic E. coli factor for adherence (efa1) and lymphostatin (lifA). Therefore, a cosmid library was constructed from SF STEC O157:H- strain 493/89, and one clone containing these fragments was sequenced. This sequencing demonstrated a 9669-bp open reading frame (ORF) that had 99.9% sequence homology to efa1 of STEC O111:H- strain E45035 and to lifA of an enteropathogenic E. coli O127:H6 strain E2348/69. In STEC O157:H7 strain EDL933, only small (ca. 3 kb) initial and terminal fragments of this ORF are present. PCR analysis with primers complementary to the efa1/lifA sequence of strain 493/89 indicated that the complete sequence is present in each of 10 SF STEC O157:H- isolates but in none of 10 STEC O157:H7 strains investigated. The presence of the complete efa1/lifA also in both tested E. coli O55:H7 strains supports the hypothesis that SF STEC O157:H- are phylogenetically closer to the proposed E. coli O55:H7 ancestor than STEC O157:H7. Our data demonstrate the presence of a potential virulence gene in SF STEC O157:H- that is only rudimentarily present in STEC O157:H7.
authors.affiliation: Institut für Hygiene, Universitätsklinikum Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Janka
authors.forename: Martina
authors.initials: M
authors.lastname: Bielaszewska
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dobrindt
authors.forename: Helge
authors.initials: H
authors.lastname: Karch
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005285:Fermentation; D015723:Gene Library; D006801:Humans; D009693:Nucleic Acid Hybridization; D016366:Open Reading Frames / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D022603:Shiga Toxins / Q000096:biosynthesis / Q000378:metabolism; D013012:Sorbitol / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; C404907:Efa1 protein, E coli; D029968:Escherichia coli Proteins; D022603:Shiga Toxins; C406587:lymphostatin protein, E coli; D013012:Sorbitol