title: Whole genome sequencing improved case ascertainment in an outbreak of Shiga toxin-producing Escherichia coli O157 associated with raw drinking milk.
abstract: Five cases of STEC O157 phage type (PT) 21/28 reported consumption of raw cows' drinking milk (RDM) produced at a dairy farm in the South West of England. STEC O157 PT21/28 was isolated from faecal specimens from milking cows on the implicated farm. Whole genome sequencing (WGS) showed that human and cattle isolates were the same strain. Further analysis of WGS data confirmed that sequences of isolates from an additional four cases (who did not report consumption of RDM when first questioned) fell within the same five single nucleotide polymorphism cluster as the initial five cases epidemiologically linked to the consumption of RDM. These four additional cases identified by WGS were investigated further and were, ultimately, associated with the implicated farm. The RDM outbreak strain encoded stx2a, which is associated with increased pathogenicity and severity of symptoms. Further epidemiological analysis showed that 70% of isolates within a wider cluster containing the outbreak strain were from cases residing in, or linked to, the same geographical region of England. During this RDM outbreak, use of WGS improved case ascertainment and provided insights into the evolution of a highly pathogenic clade of STEC O157 PT21/28 stx2a associated with the South West of England.
authors.affiliation: Devon, Cornwall and Somerset Public Health England Centre,Exeter,Devon,UK.
authors.forename: H
authors.initials: H
authors.lastname: Butcher
authors.affiliation: Gastrointestinal and Emerging Zoonotic Infections Department,Public Health England,UK.
authors.forename: R
authors.initials: R
authors.lastname: Elson
authors.affiliation: Gastrointestinal Bacteria Reference Unit,Public Health England,London,UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Chattaway
authors.affiliation: Animal and Plant Health Agency,Veterinary Investigation Centre,Thirsk,Yorkshire,UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Featherstone
authors.affiliation: Food Water and Environmental Microbiology Laboratory Services,Public Health England,UK.
authors.forename: C
authors.initials: C
authors.lastname: Willis
authors.affiliation: Food Water and Environmental Microbiology Laboratory Services,Public Health England,UK.
authors.forename: F
authors.initials: F
authors.lastname: Jorgensen
authors.affiliation: Gastrointestinal Bacteria Reference Unit,Public Health England,London,UK.
authors.forename: T J
authors.initials: TJ
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: Food Water and Environmental Microbiology Laboratory Services,Public Health England,UK.
authors.forename: J
authors.initials: J
authors.lastname: McLAUCHLIN
authors.affiliation: Field Epidemiology Service,Public Health England,UK.
authors.forename: C R
authors.initials: CR
authors.lastname: Beck
authors.affiliation: Devon, Cornwall and Somerset Public Health England Centre,Exeter,Devon,UK.
authors.forename: S
authors.initials: S
authors.lastname: Harrison
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology; D005260:Female; D016680:Genome, Bacterial; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000382:microbiology*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D055815:Young Adult
keywords: Bacterial typing; Escherichia coli; foodborne infections; gastrointestinal infections; public health microbiology