Workplace outbreak of enterotoxigenic Escherichia coli O159 enteritis linked to kimchi consumption in Daejeon, Korea, 2024.

OBJECTIVES

In August 2024, a large outbreak of gastrointestinal illness was reported among workers at a workplace in Daejeon, Korea, where bulk meals were served. This study investigated the epidemiological and microbiological characteristics of the outbreak to identify the causative pathogen, the infection source, and possible contamination routes.

METHODS

A comprehensive epidemiological investigation was conducted, including case identification, retrospective cohort analysis, laboratory confirmation, and pulsed-field gel electrophoresis (PFGE). Attack rates, relative risks (RRs), and 95% confidence intervals (CIs) were calculated. Environmental and distribution chain assessments were also performed to trace the sources and transmission pathways.

RESULTS

A total of 77 individuals met the case definition, including 75 symptomatic cases and 2 asymptomatic food handlers who tested positive for enterotoxigenic Escherichia coli (ETEC) O159. Among the 75 symptomatic cases, 25 were laboratory-confirmed, resulting in a total of 27 laboratory-confirmed cases. The mean and median incubation periods were 70.5 hours and 72.0 hours, respectively. The attack rate was significantly higher among kimchi consumers than among non-consumers (RR, 1.47; 95% CI, 1.08 to 2.00). PFGE identified ETCX01.332 as the predominant pattern among patient and kimchi isolates. Distribution tracing indicated that the implicated kimchi was produced at a factory in Gyeonggi Province and supplied to multiple catering facilities, leading to additional outbreaks in Seoul and Gyeonggi Province. However, the exact contamination point(s) during production or distribution remained undetermined.

CONCLUSIONS

This outbreak was attributed to ETEC O159, with kimchi suspected as the infection source. These findings provide rare evidence implicating non-heated fermented foods in ETEC transmission and highlight the need for strengthened hygiene standards and real-time monitoring throughout the production, distribution, and handling of fermented foods.