Longitudinal monitoring of global prevalence, genomic characterization and transmission routes of Salmonella Derby strains from food, humans and the environment.

Salmonella enterica serovar Derby is a foodborne pathogen that poses an increasing threat to global public health due to its widespread distribution and increasing antimicrobial resistance (AMR). Herein, a comprehensive genomic overview of 2628 S. Derby strains isolated from 27 countries between 1905 and 2023 was performed to investigate the AMR determinants, population structure, and transmission routes. These isolates were primarily sourced from food items (1393, 53.01 %), particularly pork products (1090, 41.48 %). S. Derby isolates belonged to 21 distinct sequence types (STs), with ST40 being the most prevalent. At the AMR level, ST40, China, and swine exhibited higher numbers and diversity of ARGs, with steady increases in resistance to fluoroquinolones and third-generation cephalosporins. Genomic epidemiology revealed seven lineages in the ST40 population, clustering of strains from different countries within China, suggesting concurrent global circulation and local expansion in China. ST40 S. Derby is also an open genome with ongoing gene acquisition for adaptation to various ecological niches. European countries had been identified as potential hubs for the emergence of ST40 S. Derby and transmitted globally. Furthermore, no significant differences were observed in the distribution of isolation source in each cluster, transmission analyses suggest that swine and pork products act as potential intermediaries in human S. Derby infections. Collectively, this study provides critical insights for food safety initiatives tackling the challenge of S. Derby, aiming to reduce the risk of food product contamination, thereby safeguarding public health.