Salmonella infection causes serious economic losses, threatens food safety, and is one of the most important diseases threatening meat duck farming. The gut microbiome is critical in providing resistance against colonization by exogenous microorganisms. Studying the relationship between Salmonella and gut microbiota can help us better understand the threat of the pathogenic mechanism of Salmonella and provide a more scientific theoretical basis for its prevention and treatment. This study uses Salmonella Typhimurium as the research object and Cherry Valley meat duck as the model with which to study the impact of Salmonella infection on ducks. In this field trial, 2 × 10⁸ CFUs Salmonella Typhimurium were administered to 3-day-old ducks. After infection, duck viscera were collected to detect the colonization of Salmonella, and cecal contents were collected to analyze the changes in gut microbiota. The results show that Salmonella Typhimurium can colonize ducks three days after infection and alter the gut microbiota composition, mainly by increasing the abundance of Ruminococcaceae and Lachnospiraceae. In conclusion, Salmonella Typhimurium infection significantly alters the intestinal microbiota of ducks and poses a serious public health risk.

Salmonella is a major threat to both human and animal health. However, the diversity and antibiotic resistance of animal-derived Salmonella and their association with human infections remain largely unexplored. In this study, Salmonella strains were isolated, identified, and sequenced from dead embryos and cloacal swab samples obtained from 278 large-scale duck farms in 11 cities in Shandong Province. The results show that a total of 57 Salmonella strains were isolated, with the dominant sequence types (ST) being ST17 (15/57) and ST19 (9/57), while the dominant serotypes were S. Indiana (15/57) and S. Typhimurium (11/57). Furthermore, genomic analysis has revealed the presence of prevalent antibiotic resistance genes (ARGs), which are often associated with co-transfer mechanisms. Over 52.63% of the strains were observed to carry two or more ARGs, especially one Salmonella strain that carried twenty-eight distinct ARGs. Furthermore, core genome multilocus sequence typing analysis (cgMLST) indicated that the 57 Salmonella strains may have a close relationship, which could be clonally transmitted among different cities. The results demonstrated a close relationship between the Salmonella strains identified in diverse geographical regions, suggesting that these strains may have been widely disseminated through clonal transmission. The mutation analysis reveals significant mutations at parC (T57S), gyrA (S83F), parC (S80R), gyrA (D87N), and gyrA (S83Y). These findings emphasize the necessity for monitoring and controlling Salmonella infections in animals, as they may serve as a reservoir for ARGs with the potential to affect human health or even be the source of pathogens that infect humans.