Food-borne outbreak of Listeria monocytogenes in school students in Seoul, Korea

Abstract

In September 2018, an outbreak of Listeriosis cases in Korea was traced to food involved, using retrospective cohort studies and PFGE analyses. This study aimed to describe the first L.monocytogenes outbreak identified in Korea. We confirmed the presence of Serovar (4C) and virulence genes, and evaluated the genetic correlation between isolates by restriction digestion patterns of ApaI and AscI. Based on the epidemiological association, it is presumed that the seasoned crab meat with bean sprouts are contaminated by cross contamination during the bean sprouts washing (relative risk was 1.24; p-value: 0.0021 and they possessed virulence genes. Therefore, active laboratory surveillance is necessary to recognize the risk of L. monocytogenes in Korea.

Whole-genome sequencing of Listeria monocytogenes isolated from the first listeriosis foodborne outbreak in South Korea

“…Over 100 foodborne outbreaks in South Korea are caused every year by pathogenic bacteria such as Salmonella, pathogenic Escherichia coli, and Campylobacter jejuni (MFDS, 2022). However, the first foodborne outbreak caused by L. monocytogenes in South Korea occurred in 2018 (Han et al, 2019). In this outbreak, 294 people experienced listeriosis symptoms after lunch served at a school cafeteria, and 64 were confirmed to be infected with L. monocytogenes (Han et al, 2019).…”

“…However, the first foodborne outbreak caused by L. monocytogenes in South Korea occurred in 2018 (Han et al, 2019). In this outbreak, 294 people experienced listeriosis symptoms after lunch served at a school cafeteria, and 64 were confirmed to be infected with L. monocytogenes (Han et al, 2019). L. monocytogenes was isolated from seasoned crab meat with bean sprouts (served at lunch), spicy cold noodles and green pudding salad (both served at dinner).…”

“…L. monocytogenes was isolated from seasoned crab meat with bean sprouts (served at lunch), spicy cold noodles and green pudding salad (both served at dinner). A retrospective cohort study and PFGE analysis showed that seasoned crab meat with bean sprouts was significantly associated with the disease (Han et al, 2019). Although listeriosis has been uncommon in Korea, the incidence of listeriosis among the elderly and immunocompromised patients in three Korean hospitals increased from 1.8 per 100,000 inpatients in 2006-2012to 5.5 in 2013-2016(Choi et al, 2018.…”

“…Listeria monocytogenes strains isolated from the aforementioned listeriosis outbreak (FSCNU0110) and foods sold in South Korea between 2005 and 2021 were used for serotyping, MLST, and antibiotic resistance assays (Table 1). Strain FSCNU0110 was isolated from feces of a patient who experienced two or more episodes of fever, abdominal pain, diarrhea, and vomiting after consuming food in the school cafeteria (Han et al, 2019). Bacterial cells were plated on brain heart infusion (BHI) agar (MB cell, Seoul, South Korea) and incubated at 35 ± 1°C for 18-24 h. Colonies on the BHI plate were confirmed as L. monocytogenes using the VITEK-2 automated microbial identification system (BioMérieux, Marcy-l'Etoile, France).…”