Virulence Factors and Resistance Genes of Salmonella: A Comprehensive Review

Abstract

Salmonella is a major foodborne pathogen with clinical manifestations ranging from self-limited gastroenteritis to systemic typhoid disease. Its pathogenicity reflects coordinated virulence mechanisms that support adhesion, invasion, intracellular survival, immune modulation and persistence in diverse host environments. This review synthesises the principal virulence determinants of Salmonella, including Salmonella Pathogenicity Islands, type III secretion systems, effector proteins, adhesins, fimbriae, toxins, iron-acquisition systems, lipopolysaccharide modifications, outer membrane proteins, two-component regulatory systems and biofilm formation. It also summarises key antimicrobial resistance mechanisms and resistance gene families, including beta-lactamases, carbapenemases, plasmid-mediated quinolone resistance determinants, aminoglycoside-modifying enzymes, tetracycline resistance genes, chloramphenicol resistance determinants, sulfonamide and trimethoprim resistance genes, mcr-associated colistin resistance and mobile genetic elements such as plasmids, integrons and genomic islands. The review highlights the relevance of co-existing virulence and resistance traits in clinical, environmental and food-chain isolates and emphasises the importance of interpreting these traits within a One Health framework. Overall, the manuscript indicates that improved genomic surveillance, antimicrobial stewardship and the development of targeted therapeutic or anti-virulence approaches are needed to address the combined challenge of Salmonella pathogenicity and antimicrobial resistance.