Genomic islands associated with the dissemination of multidrug resistance in clinically important pathogenic bacteria

OBJECTIVES: To elucidate the role of genomic islands (GIs) as key vehicles of horizontal gene transfer in disseminating antibiotic-resistance genes (ARGs) across bacterial species and in fostering multidrug-resistant (MDR) strain emergence, and to provide a comprehensive overview of current knowledge. METHODS: We integrated recent literature on mobile genomic islands (GIs), summarized their basic architecture and functional features, systematically catalogued the types/subtypes of resistance islands identified in major epidemic pathogens (Salmonella, Proteus mirabilis, Staphylococcus aureus, Acinetobacter baumannii, etc.), and delineated their horizontal transfer mechanisms. RESULTS: (1) GIs can integrate into host chromosomes, excise under specific cues, and transfer to new recipients, thereby facilitating the spread of clinically important ARGs. (2) Diverse novel multidrug-resistant genomic islands have been characterized in the above pathogens. CONCLUSIONS: GIs are one of the key vehicles that facilitate the dissemination of ARGs and the evolution of bacterial multidrug resistance. A systematic understanding of their structure, transfer mechanisms and core functions offers a reference framework for future surveillance of multidrug-resistant genomic islands and for developing countermeasures against antimicrobial resistance.