title: Characterization of an emergent clone of enteroinvasive Escherichia coli circulating in Europe.
abstract: Enteroinvasive Escherichia coli (EIEC) cause intestinal illness indistinguishable from that caused by Shigella, mainly in developing countries. Recently an upsurge of cases of EIEC infections has been observed in Europe, with two large outbreaks occurring in Italy and in the United Kingdom. We have characterized phenotypically and genotypically the strains responsible for these epidemics together with an additional isolate from a sporadic case isolated in Spain. The three isolates belonged to the same rare serotype O96:H19 and were of sequence type ST-99, never reported before in EIEC or Shigella. The EIEC strains investigated possessed all the virulence genes harboured on the large plasmid conferring the invasive phenotype to EIEC and Shigella while showing only some of the known chromosomal virulence genes and none of the described pathoadaptative mutations. At the same time, they displayed motility abilities and biochemical requirements resembling more closely those of the non-pathogenic E. coli rather than the EIEC and Shigella strains used as reference. Our observations suggested that the O96:H19 strains belong to an emerging EIEC clone, which could be the result of a recent event of acquisition of the invasion plasmid by commensal E. coli.
authors.affiliation: European Union Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Italy. Electronic address: valeria.michelacci@iss.it.
authors.forename: V
authors.initials: V
authors.lastname: Michelacci
authors.affiliation: Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Biology and Biotechnology 'C. Darwin', Sapienza Università di Roma, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Prosseda
authors.affiliation: European Union Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Maugliani
authors.affiliation: European Union Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Tozzoli
authors.affiliation: Laboratory of Enterobacteriaceae, Service of Bacteriology, National Center of Microbiology, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Sanchez
authors.affiliation: Laboratory of Enterobacteriaceae, Service of Bacteriology, National Center of Microbiology, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Herrera-León
authors.affiliation: Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK.
authors.forename: T
authors.initials: T
authors.lastname: Dallman
authors.affiliation: Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Jenkins
authors.affiliation: European Union Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Caprioli
authors.affiliation: European Union Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Morabito
mesh_terms: D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005060:Europe / Q000453:epidemiology; D056084:Genetic Fitness; D016680:Genome, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D058885:Multilocus Sequence Typing; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D014774:Virulence / Q000235:genetics
keywords: Emergence of new pathogenic types; Shigella; enteroinvasive Escherichia coli; genomic characterization; outbreaks of infection