title: Consecutive Outbreaks of Enterotoxigenic Escherichia coli O6 in Schools in South Korea Caused by Contamination of Fermented Vegetable Kimchi.
abstract: Two outbreaks of gastroenteritis occurred in South Korea, affecting a middle school in the Jeollanam-do province in 2013 (Outbreak 1) and 10 schools in the Incheon province in 2014 (Outbreak 2). We investigated the outbreaks to identify the pathogen and mode of transmission.
  
  
  
  A retrospective cohort study was conducted in the Outbreak 1; and case-control studies were performed for the Outbreak 2. Samples from students, environments, and preserved food items were collected and pulsed-field gel electrophoresis (PFGE) was conducted to identify strains of pathogen.
  
  
  
  We identified 167 and 1022 students who met the case definition (≥3 loose stools in any 24-h period) in the Outbreaks 1 and 2, respectively. The consumption of cabbage kimchi and young radish kimchi were significantly associated with the illness. Adjusted odds ratios of kimchi were 2.62-11.74. In the Outbreak 1, cabbage kimchi was made and consumed in the school restaurant and in the Outbreak 2, young radish kimchi was supplied by food company X and distributed to all the 10 schools in the Incheon province. Enterotoxigenic Escherichia coli (ETEC) O6 was isolated from fecal samples in 375 cases (33.9%) and from kimchi samples. PFGE patterns of the outbreak strains isolated from cases and food were indistinguishable in each outbreak.
  
  
  
  The suspected food vehicle in these two consecutive outbreaks was kimchi contaminated with ETEC O6. We recommend continued monitoring and stricter sanitation requirements for the food supply process in Korea, especially in relation to kimchi.
authors.affiliation: 1 Division of Epidemic Intelligence Service, Korea Centers for Disease Control and Prevention , Cheongju, Republic of Korea.
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Shin
authors.affiliation: 2 Division of Microbiology, Jeollanam-do Institute of Public Health and Environment , Gwangju, Republic of Korea.
authors.forename: Ki-Bok
authors.initials: KB
authors.lastname: Yoon
authors.affiliation: 2 Division of Microbiology, Jeollanam-do Institute of Public Health and Environment , Gwangju, Republic of Korea.
authors.forename: Doo-Young
authors.initials: DY
authors.lastname: Jeon
authors.affiliation: 3 Division of Microbiology, Incheon Research Institute of Public Health and Environment , Incheon, Republic of Korea.
authors.forename: Sung-Suk
authors.initials: SS
authors.lastname: Oh
authors.affiliation: 4 Division of Enteric Diseases, Center for Infectious Diseases, Korea National Institute of Health , Cheongju, Republic of Korea.
authors.forename: Kyung-Hwan
authors.initials: KH
authors.lastname: Oh
authors.affiliation: 4 Division of Enteric Diseases, Center for Infectious Diseases, Korea National Institute of Health , Cheongju, Republic of Korea.
authors.forename: Gyung Tae
authors.initials: GT
authors.lastname: Chung
authors.affiliation: 1 Division of Epidemic Intelligence Service, Korea Centers for Disease Control and Prevention , Cheongju, Republic of Korea.
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: 4 Division of Enteric Diseases, Center for Infectious Diseases, Korea National Institute of Health , Cheongju, Republic of Korea.
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Cho
mesh_terms: D001937:Brassica / Q000009:adverse effects / Q000382:microbiology; D016022:Case-Control Studies; D015331:Cohort Studies; D004196:Disease Outbreaks; D054307:Enterotoxigenic Escherichia coli / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology / Q000635:transmission; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D005506:Food Contamination; D005522:Food Services; D057141:Food, Preserved / Q000009:adverse effects* / Q000382:microbiology; D005517:Foodborne Diseases / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology; D005759:Gastroenteritis / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology; D006801:Humans; D062409:Lunch; D058889:Molecular Typing; D018515:Plant Leaves / Q000009:adverse effects / Q000382:microbiology; D018517:Plant Roots / Q000009:adverse effects / Q000382:microbiology; D031224:Raphanus / Q000009:adverse effects / Q000382:microbiology; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012306:Risk; D012574:Schools
keywords: ETEC; PFGE; kimchi; outbreak of gastroenteritis