First evidence of microplastic-associated extended-spectrum beta-lactamase (ESBL)-producing bacteria in the Red River Delta, Vietnam

This study investigated the relationship between MiPs, antibiotic resistance genes (ARGs), and water quality in the Red River Delta. MiPs were collected from water samples at four locations: Hanoi, Ha Nam, Nam Dinh, and Cat Ba Island. Bacteria isolated from MiPs and the surrounding water were analyzed for β-lactamase genes. Polyethylene terephthalate (PET) and polytridecanolactone (PTDL) exhibited notable correlations with coefficients with microbial abundance on MiPs. Aeromonas (99.2 % of all isolates) were the most common bacteria isolated from MiPs, with a fewer Escherichia coli (0.83 %). Of 207 bacterial strains isolated from microplastic, 23 (~11 % of total) were found to carry antibiotic resistance genes, mostly bla_TEM (13/23; 56.5 %), bla_SHV (9/23; 39.1 %) and bla_CTXM-9 (1/23; 4.3 %). All seven environmental factors measured were found to affect the distribution of ARGs and ARBs on MiP surfaces. Chlorophyll-a showed a strong positive correlation with ARB abundance, suggesting a potential link between primary productivity and bacterial colonization. This study is one of the first to report the association of MPs with antibiotic-resistant microbiota and genes. The presence of ARGs on MiPs in areas with high human population highlights the need for effective pollution management strategies to mitigate the risks associated with AMR.