Comparative Analysis of Salmonella enterica subsp. enterica Serovar Thompson Isolates associated with Outbreaks Using PFGE and wgMLST

Publisher: Korean Society for Microbiology and Biotechnology Country of Publication: Korea (South) NLM ID: 9431852 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1738-8872 (Electronic) Linking ISSN: 10177825 NLM ISO Abbreviation: J Microbiol Biotechnol Subsets: MEDLINE

Publication: 2002- : Seoul : Korean Society for Microbiology and Biotechnology
Original Publication: Seoul : Korean Society for Applied Microbiology, 1991-2001.

Salmonella enterica*/genetics ; Foodborne Diseases*/epidemiology; Humans ; Multilocus Sequence Typing ; Serogroup ; Disease Outbreaks ; Republic of Korea/epidemiology ; Genomics ; Electrophoresis, Gel, Pulsed-Field

The strains associated with foodborne Salmonella enterica Thompson outbreaks in Korea have not been identified. Therefore, we characterized S. Thompson strains isolated from chocolate cakes linked to foodborne outbreaks in Korea. A total of 56 strains were isolated from preserved cake products, products in the supply chain distribution, the manufacturer's apparatus, and egg white liquid products used for cream preparation. Subsequently, serological typing, pathogenic gene-targeted polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE), and whole-genome multi-locus sequence typing (wgMLST) were performed to characterize these isolates. The antigen formula of all isolates was 7:k:1,5, namely Salmonella enterica subsp. enterica Serovar Thompson. All 56 isolates harbored invA , his , hin , and stn , and were negative for sefA and spvC based on gene-targeted PCR analyses. Based on PFGE results, these isolates were classified into one group based on the same SP6X01.011 pattern with 100% similarity. We selected 19 strains based on the region and sample type, which were subjected to wgMLST. Although the examined strains showed 100% similarity, they were classified into seven clusters based on allelic differences. According to our findings, the cause of these outbreaks was chocolate cake manufactured with egg white liquid contaminated with the same Salmonella Thompson. Additionally, comparative analysis of wgMLST on domestic isolates of S . Thompson from the three outbreaks showed genetic similarities of over 99.6%. Based on the results, the PFGE and wgMLST combination can provide highly resolved phylogeny and reliable evidence during Salmonella outbreak investigations.

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Keywords: Salmonella enterica serovar Thompson; chocolate cake; foodborne outbreak; pulsed-field gel electrophoresis; whole-genome multi-locus sequence typing

Salmonella enterica subsp. enterica

Date Created: 20221118 Date Completed: 20221229 Latest Revision: 20230201

20240829

PMC9843761

10.4014/jmb.2210.10010

36398444