Emergence of rapidly spreading antimicrobial-resistant Salmonella in traditional blood-based foods

Objectives This study aims to investigate the survival ability and risk of Salmonella isolated from traditional blood-based food, using both phtnotypic and genotypic analysis.Materials and Methods We characterized and identified seventeen Salmonella isolates using 16s rRNA sequencing, real-time PCR and whole-genome sequencing (WGS). Cell counts were recorded to monitor growth ability and temperature tolerance. Virulence genes and whole genome phylogenies were confirmed by WGS. The minimum inhibitory concentration (MIC) of corresponding strains to different antibiotics and antimicrobial resistance (AMR) genes predicted by WGS were evaluated.Results In this study, we characterized 17 Salmonella isolates obtained from contaminated traditional blood-based food in China. Compared to laboratory strain S. Typhimurium ATCC 14028, these Salmonella isolates generally grew more rapidly and developed less biofilm, but their tolerance to food processing-associated cold and heat stresses was distinct. Whole-genome phylogenies pointed out the potential for cross-contamination during food practices. In addition, 21 antibiotic-resistance genes were found among blood-based food isolates, including high-prevalent resistance genes gyrA (including associated mutations D87G and S83F), blaTEM, and aadA1. Antibiotic susceptibility test confirmed the in-silico prediction and revealed a 41.18% (7/17) multidrug resistance (MDR) rate. Resistance to ceftiofur, kanamycin, and nalidixic acid was observed without corresponding resistance genes, suggesting overlooked resistance mechanisms.Conclusions This study revisited microbial safety concerns associated with traditional blood-based food and underlined the emergence of high-risk MDR Salmonella strains. It also underscores the importance of implementing better hygiene practices in the production and handling of traditional food products. Graphical Abstract