Whole-Genome Sequencing Analysis of Antimicrobial Resistance, Virulence Factors, and Genetic Diversity of Salmonella Isolated from Wenzhou, China

Salmonella species are important foodborne pathogens worldwide. Salmonella pathogenicity is associated with multiple virulence factors and enhanced antimicrobial resistance. To determine the molecular characteristics and genetic correlations of Salmonella, 24 strains of Salmonella isolated from different sources (raw poultry, human stool, and food) in the Wenzhou area were investigated to determine the distribution of antimicrobial resistance and virulence determinants using whole-genome sequencing (WGS). Aminoglycoside-resistance genes were detected in all samples. Over half of the samples found antimicrobial resistance genes (ARGs) and point mutations for several clinically frequently used antibiotic, β-lactamases, tetracyclines, and fluoroquinolones. Of these strains, 62.5% were predicted to be multidrug-resistant (MDR). The quinolone-modifying enzyme gene aac(6)-Ib-cr, detected in five samples (S1–S4 and S10), were located on integrons. Analysis of Salmonella pathogenicity island (SPI) profiles suggests that serotypes with close genetic relationships share the same distribution of virulence factors, revealing a link between genotype and SPI profiles. CgMLST analysis indicated that five isolates S14–S18 were closely related to strains originating from the UK, suggesting that they may have been introduced from the UK. Data from this study may enrich the molecular traceability database for Salmonella and provide a basis for effective public health policies.