Abstract：Objective To investigate the molecular typing and drug resistance of Salmonella in market-sold raw livestock meats in Shaoxing City, Zhejiang Province, so as to provide the basis for the prevention and control of drug-resistant Salmonella. MethodsSalmonella isolates were detected and serotyped from raw livestock meat samples collected from supermarkets, agricultural markets and restaurants in Shaoxing City between March and November 2023. Molecular typing was performed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Antibiotic resistance phenotypes and resistance gene analyses were conducted using broth microdilution method and whole genome sequencing. Results A total of 34 Salmonella isolates were detected from 329 samples and the positive rate was 10.33%. There were 14 serotypes, with S. Rissen (9 isolates, 26.47%) and S. London (8 isolates, 23.53%) being dominant. PFGE typing revealed 31 band patterns and 23 banding pattern clusters of Salmonella, and the similarity ranged from 30.80% to 100.00%, without dominant band patterns. MLST identified 15 sequence typing (ST) types, and S. Rissen were all ST469 and S. London were all ST155. Salmonella strains exhibited high levels of resistance to tetracycline (44.12%) and ampicillin (35.29%). Thirteen resistance patterns were identified, with 8 multidrug resistant patterns (29.41%). There were 8 classes of 14 resistance genes, with aminoglycoside resistance gene aac(6' )-Iaa found in 100.00% of the strains. The highest concordance rate between the resistance phenotype and gene was observed for phenicol antibiotics (97.06%), while there was no concordance between the quinolone resistance phenotype and genes. ConclusionsS. Rissen and S. London are the predominant serotypes in market-sold raw livestock meats in Shaoxing City. The PFGE band types of the Salmonella isolates show polymorphism distribution, and MLST are mainly ST469 and ST155. The isolates have high levels of resistance to tetracycline and ampicillin, manifesting multidrug resistance.
