Genomic Surveillance of Salmonella London and Rissen Reveals International Transmission Patterns and Expanding Antimicrobial Resistance - Shanghai Municipality, China, 2020-2024.

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?: Non-typhoidal Salmonella (NTS) represents a leading cause of foodborne gastroenteritis worldwide. The epidemiological landscape of NTS continues to evolve, with specific serotypes emerging as significant human pathogens through contaminated food products. This evolution occurs particularly within the context of globalized food supply chains and widespread antimicrobial use in agricultural settings.

WHAT IS ADDED BY THIS REPORT?: This study integrated local isolates from Shanghai with global genomic data to reveal distinct international transmission patterns for Salmonella London and Rissen. S. London disseminated through historical, geographically segregated clades, whereas S. Rissen demonstrated recent intercontinental mixing, with Thailand identified as the primary global source. Our analysis identified high-risk plasmids harboring up to 15 resistance genes and demonstrated that Chinese isolates carried the highest antimicrobial resistance burden globally.

WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?: The global dissemination of these pathogens is directly linked to international food trade networks. Our findings necessitate a paradigm shift toward integrated global One Health surveillance that bridges human, animal, and food sectors. Implementing harmonized international policies, rigorous trade monitoring, and enhanced antimicrobial stewardship programs is essential to contain the transnational threat posed by resistant foodborne pathogens.