Whole-Genome Sequencing Provides Insight Into Antimicrobial Resistance and Molecular Characteristics of From Livestock Meat and Diarrhea Patient in Hanzhong, China.

is a major zoonotic pathogen, which usually contaminates food resulting in salmonellosis in humans. Exploring the characteristics and origins of is essential in formulating prevention and control measures for infection. We used slide agglutination, antimicrobial susceptibility testing, and whole-genome sequencing to analyze and compare 's phenotype, genotyping diversity, and genetic relatedness from livestock meat and diarrhea patients in Hanzhong, China, from 2018 to 2020. Totally 216 enterica isolates were screened from frozen whole chicken carcasses (44.3%, 70/158), frozen raw ground pork (36.2%, 59/163), and diarrhea patients (4.4%, 87/1964). Typhimurium was the dominant serotype. Notably, compared with other sources, isolates obtained from frozen whole chicken carcasses showed significant resistance to third-generation cephalosporin and fluoroquinolones ( < 0.05). All strains were assigned into 36 sequence types (STs) and two novel STs, and an excellent consistency was observed between ST and serotype. Genomic data revealed that extended-spectrum β-lactamase genes were responsible for third-generation cephalosporin resistance in 52 strains, and the most predominant resistance determinant was . Furthermore, of the 60 ciprofloxacin-resistant isolates, five single-base mutations in quinolone resistance-determining regions were identified in or , and the plasmid-mediated quinolone resistance gene was most often detected. The cgMLST clusters show that five clusters among four serotypes (including . Typhimurium, . London, . Derby, and . Agona) cover samples from diarrhea patients and livestock meat pathway isolate, indicating a possibility of cross-host transmission. In conclusion, the livestock meat isolates have a higher level of resistance than diarrhea patients' isolates and could be an essential source of human infection.