Introduction
Non-typhoidal Salmonella enterica causes food-borne salmonellosis and has become a global health threat . The Salmonella entericaserovar Enteritidis is frequently isolated from human patients with salmonellosis caused by consumption of contaminated chicken meat and chicken products such as eggs . Epidemiological sources ofSalmonella outbreaks have been investigated using pulsed-field gel electrophoresis (PFGE) and multiple locus variable-number tandem repeats (MLVA) analysis. In previous studies, PFGE and MLVA analysis successfully detected the genetic relationship between SalmonellaEnteritidis strains isolated from human patients or poultry sources in Korea . However, the discrimination power of these methods for genetically closely related Salmonella Enteritidis strains is limited . The next-generation sequencing methodologies such as whole-genome sequencing (WGS) has been improved the resolution of genome analyses, such that sources of Salmonella outbreaks can be traced without using the genotyping approaches described above . Recently, isolation of MDR Salmonella has been increased from human and poultry, and these MDR Salmonella had the same antibiotic resistance phenotype . However, the genetic relationship betweenSalmonella Enteritidis isolated from human and poultry sources in Korea has not been investigated using WGS yet. Here, we isolated seven MDR Salmonella Enteritidis strains from poultry sources in Korea and sequenced their genomes using the Oxford Nanopore approach. In order to investigate the relationships between Salmonella strains, the whole genome sequences of the MDR isolates were compared with whole genome sequences of the previously reported Korean SalmonellaEnteritidis strains using whole genome single nucleotide polymorphism (SNP) - based phylogenetic analysis and comparative plasmid analysis.