Microplastic-Mediated Dissemination of Antibiotic Resistance Genes in Marine Environments: Mechanisms, Environmental Modulators, and Emerging Risks

The convergence of global plastic pollution and antimicrobial resistance crises has intensified concerns about the role of microplastics (MPs) in disseminating antibiotic resistance genes (ARGs) in marine environments. This review synthesizes the mechanistic pathways through which MPs act as vectors for ARG propagation, supported by a bibliometric analysis of 144 studies retrieved from Scopus. MPs possess distinct physicochemical properties such as nanoplastic formation, polymer-specific sorption, weathering-induced oxidation, and additive leachate release that facilitate microbial colonization and biofilm formation. These plastisphere biofilms, enriched with mobile genetic elements including integrons, transposons, and plasmids, promote ARG transfer via conjugation, transformation, and transduction. Environmental modulators like salinity, oxygen, nutrients, pH, UV exposure, and reactive oxygen species further accelerate horizontal gene transfer, while co-selection pressures from heavy metals and antibiotics amplify resistance dissemination. Bibliometric mapping reveals a sharp rise in publications since 2018, with China leading contributions and major research themes centered on horizontal gene transfer, metagenomics, nanoplastics, and biofilm-mediated resistome evolution. Overall, marine MPs substantially intensify ARG spread through complex microbe–plastic–pollutant interactions, posing significant ecological and public health risks. Addressing current gaps, such as limited field validation, underexplored nanoplastic mechanisms, geographic bias, and lack of standardized monitoring, requires harmonized surveillance, omics integration, pollutant mixture modeling, and One Health-based risk assessment to inform global policy interventions.