title: An outbreak of gastroenteritis caused by Salmonella enterica serotype Enteritidis traced to cream cakes.
abstract: BACKGROUND
  This paper describes the epidemiological, microbiological and environmental investigations conducted during an outbreak of Salmonella gastroenteritis in Singapore.
  
  
  METHODS
  A case-control study was undertaken to identify the vehicle of transmission. Microbiological testing was performed on faecal, food and environmental samples. Isolates of Salmonella were further characterized by phage typing and ribotyping.
  
  
  RESULTS
  There were 216 gastroenteritis cases reported from 20 November to 4 December 2007. The causative agent was identified as Salmonella enterica subspecies enterica serotype Enteritidis for 14 out of 20 cases tested. The vehicle of transmission was traced to cream cakes produced by a bakery and sold at its retail outlets (P < 0.001, OR = 143.00, 95% Cl = 27.23-759.10). More than two-thirds of the 40 Salmonella strains isolated from hospitalized cases, food samples and asymptomatic food handlers were of phage type 1; the others reacted but did not conform to any phage type. The phage types correlated well with their unique antibiograms. The ribotype patterns of 22 selected isolates tested were highly similar, indicating genetic relatedness. The dendrogram of the strains from the outbreak showed distinct clustering and correlation compared to the non-outbreak strains, confirming a common source of infection.
  
  
  CONCLUSIONS
  The cream cakes were likely contaminated by one of the ingredients used in the icing. Cross-contamination down the production line and subsequent storage of cakes at ambient temperatures for a prolonged period before consumption could have contributed to the outbreak.
authors.affiliation: Communicable Disease Division, Ministry of Health, College of Medicine Building, 16 College Road, Singapore 169854.
authors.forename: Suhana
authors.initials: S
authors.lastname: Solhan
authors.forename: Pei Pei
authors.initials: PP
authors.lastname: Chan
authors.forename: Lalitha
authors.initials: L
authors.lastname: Kurupatham
authors.forename: Bok Huay
authors.initials: BH
authors.lastname: Foong
authors.forename: Peng Lim
authors.initials: PL
authors.lastname: Ooi
authors.forename: Lyn
authors.initials: L
authors.lastname: James
authors.forename: Leslie
authors.initials: L
authors.lastname: Phua
authors.forename: Ai Ling
authors.initials: AL
authors.lastname: Tan
authors.forename: Diana
authors.initials: D
authors.lastname: Koh
authors.forename: Kee Tai
authors.initials: KT
authors.lastname: Goh
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