title: Whole Genome Sequencing for the Retrospective Investigation of an Outbreak of Salmonella Typhimurium DT 8.
abstract: BACKGROUND
  Salmonella enterica serovar Typhimurium DT8 is uncommon within the European Union. An increase in this phage type was reported in the summer of 2013 in the States of Jersey.
  
  
  METHODS
  A total of 21 human cases with this phage type were microbiologically confirmed. Salmonella isolates from mayonnaise made using raw eggs were also confirmed as being Salmonella Typhimurium DT8. The epidemiological investigations strongly supported a link between mayonnaise consumption and illness. Whole genome sequencing (WGS) was used to retrospectively investigate this outbreak with a view to assess the similarity between the suspect food and the human isolates and to characterise a known point source outbreak to assist in development of algorithms for outbreak detection.
  
  
  RESULTS
  Sequence data showed that the outbreak associated isolates, including the food isolates, formed a tightly clustered monophyletic group, with a maximum pairwise distance of 3 single nucleotide polymorphisms.
  
  
  CONCLUSIONS
  WGS data is useful in confirming the causative agent of outbreaks where food and clinical isolates are available. This dataset, comprising a known outbreak, will be useful in the development of automatic algorithms for outbreak detection.
authors.affiliation: Public Health England.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Ashton
authors.affiliation: Public Health England, London, UK.
authors.forename: Tansy
authors.initials: T
authors.lastname: Peters
authors.affiliation: Public Health England, London, UK.
authors.forename: Linda
authors.initials: L
authors.lastname: Ameh
authors.affiliation: Environmental Health, Public Health Department Jersey, Jersey.
authors.forename: Ralph
authors.initials: R
authors.lastname: McAleer
authors.affiliation: Environmental Health, Public Health Department Jersey, Jersey.
authors.forename: Stewart
authors.initials: S
authors.lastname: Petrie
authors.affiliation: Public Health England, London, UK.
authors.forename: Satheesh
authors.initials: S
authors.lastname: Nair
authors.affiliation: Departments of Microbiology and Public Health, Jersey.
authors.forename: Ivan
authors.initials: I
authors.lastname: Muscat
authors.affiliation: Public Health England, London, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: de Pinna
authors.affiliation: Public Health England, London, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Dallman
keywords: Salmonella; duck eggs; food-borne infection; outbreaks; phylogeny