The Plastisphere Resistome: A Systematic Review of Antibiotic Resistance Genes and Resistant Bacteria on Microplastics

This systematic review will synthesize evidence on whether microplastic-associated biofilms (“plastisphere”) harbor higher levels and diversity of antimicrobial resistance (AMR) determinants than appropriate environmental comparators (e.g., surrounding bulk water/sediment/soil or non-plastic surfaces). We will include original peer-reviewed studies (field, mesocosm, or laboratory) that explicitly compare microplastics (or microplastic-associated biofilms) with a predefined comparator sampled/processed under comparable conditions. Primary outcomes will include antibiotic resistance genes (ARGs), antibiotic-resistant bacteria (ARB), and related mobile genetic elements (e.g., integrons) and/or indicators of horizontal gene transfer when reported. Searches will be conducted in PubMed/MEDLINE, Scopus, and Europe PMC. Preprints will be excluded. Two reviewers will independently screen records and extract data using a predefined extraction form, disagreements will be resolved by consensus or a third reviewer. We will perform a brief quality appraisal using a short checklist focusing on sampling/comparator adequacy, replication/statistics, contamination control, measurement transparency, and completeness of reporting. Evidence will be synthesized primarily using structured narrative synthesis, stratified by environment, polymer type, and methodological approach, with optional quantitative synthesis if sufficient methodological homogeneity is present. The review will be reported in accordance with PRISMA 2020.