Characterization of Salmonella species from poultry slaughterhouses in South Korea: carry-over transmission of Salmonella Thompson ST292 in slaughtering process

outbreaks linked to poultry meat have been reported continuously worldwide. Therefore, contamination of poultry meats in slaughterhouses is one of the critical control points for reducing disease outbreaks in humans. This study examined the carry-over contamination of species through the entire slaughtering process in South Korea. From 2018 to 2019, 1,097 samples were collected from the nine slaughterhouses distributed nationwide. One hundred and seventeen isolates of species were identified using the gene-specific polymerase chain reaction, as described previously. The serotype, phylogeny, and antimicrobial resistance of isolates were examined. Among the 117 isolates, 93 were serotyped into Mbandaka (n = 36 isolates, 30.8%), Thompson (n = 33, 28.2%), and Infantis (n = 24, 20.5%). Interestingly, allelic profiling showed that all . Mbandaka isolates belonged to the lineage of the sequence type (ST) 413, whereas all . Thompson isolates were ST292. Moreover, almost all . Thompson isolates (97.0%, 32/33 isolates) belonging to ST292 were multidrug-resistant and possessed the major virulence genes whose products are required for full virulence. Both serotypes were distributed widely throughout the slaughtering process. Pulsed-field gel electrophoretic analysis demonstrated that seven . Infantis showed 100% identities in their phylogenetic relatedness, indicating that they were sequentially transmitted along the slaughtering processes. This study provides more evidence of the carry-over transmission of species during the slaughtering processes. ST292 . Thompson is a potential pathogenic clone of species possibly associated with foodborne outbreaks in South Korea.