Plastisphere as a global hotspot for antimicrobial resistance: Systematic review and quantitative synthesis.

Plastic debris provides colonizable surfaces for microbial biofilms, the plastisphere, which is now recognized as a hotspot for antimicrobial resistance (AMR) amplification and dissemination. This PRISMA 2020-compliant synthesis covers 53 studies. Random-effects meta-analysis of 30 conjugation datasets showed enhanced horizontal gene transfer: pooled log response ratio (lnRR) = 1.93 (95% CI: 1.63-2.23), 6.9-fold (95% CI: 5.1-9.3-fold); heterogeneity was high (I2 = 85.0%; τ2 = 0.573; Q = 187.6, df = 29) and the 95% prediction interval spanned 1.5-31.3-fold. Polyvinyl chloride (PVC) biofilms showed the largest sub-group effect (lnRR = 2.72; 95% CI: 1.84-3.60; 15.2-fold), and polymer type was significant as a categorical moderator (QM = 12.3, P = 0.006; R2 = 29%) but not as a continuous ordinal score (P = 0.15). Antibiotic resistance gene (ARG) concentrations exceeded paired controls by one to three orders of magnitude (median log10 enrichment 1.98; 95-fold). Ampicillin resistance in plastisphere-associated Vibrio spp. reached 68.4% (Wilson 95% CI: 57.3-77.8%), with 32.9% multidrug-resistant. A conceptual five-stage genetic reactor lifecycle model is proposed as a heuristic, not a validated framework, identifying dispersal as the least-evidenced stage. A polymer risk hierarchy (PVC > polyethylene (PE) > polystyrene (PS), with polyethylene terephthalate (PET) lowest for ARG enrichment), an exposure-response framework and four Tier-1 knowledge gaps are established. The evidence base is geographically skewed (38% of studies from Chinese systems), and these estimates describe environmental enrichment, not realized clinical risk. They nonetheless justify incorporating polymer-additive regulation and plastisphere resistome surveillance into One Health strategies and the UN Plastics Treaty.