# An Exploratory Review of Microplastic Pollution, Associated Microbiomes and Pathogens in Water
## 3 Results and Discussion
### Most Common Microplastic-Associated Taxa and Their Relevance
A particularly substantial body of data originates from East Asia (notably China), where rapid industrial development and extensive antibiotic usage contribute to significant environmental contamination. For instance, in the Yangtze River estuary, numerous plastic samples were collected, revealing biofilms enriched with diverse ARGs; the average ARG abundances on these microplastics exceeded those found in the surrounding seawater and sediments [103]. Marine aquaculture regions, such as maritime ponds in China, are also characterized by high concentrations of ARGs on microplastics, attributed to frequent antibiotic application. One study from such an area identified up to 174 subtypes of resistance genes in the collected samples [105]. In Europe, the problem is also recognized: microplastics from the Mediterranean and Baltic Seas, as well as rivers, have been studied, with ARGs from similar classes (tetracyclines, sulphonamides, beta-lactams) detected, although typically at lower concentrations, likely due to reduced antibiotic pollution pressure [107, 108, 109]. The highest ARG concentrations are usually recorded where microplastics come into contact with intense sources of contamination: near municipal and hospital wastewater outfalls, river mouths, or fish and shrimp farms, where antibacterial agents enter the water [107, 109]. These geographic hotspots--often found along the coasts of Southeast Asia and densely populated river deltas--show the greatest diversity and density of ARGs carried by microplastics [109]. In contrast, remote waters far from pollution sources (e.g., central ocean regions, mountain lakes) also contain microplastics, but generally with a much lower ARG abundance. Nonetheless, even in these areas, the plastisphere may act as a reservoir of ARG-bearing microbes, transported over long distances by water currents [110]. Recent studies have confirmed that microplastics also act as hotspots for antibiotic resistance genes (ARGs), harbouring sulphonamide (sul1, sul2), tetracycline (tetA, tetW), macrolide (ermF), chloramphenicol (cat), aminoglycososide (aad, aac), trimethoprim (dfr), fluoroquinoline (qnr), and clinically relevant \(\beta\)-lactamase genes (blaCTX-M, blaTEM, blaSHV) [109, 111, 112, 113]. Notably, plastic types like PE, PP, PS, PET, and PVC exhibit differential ARG enrichment due to surface chemistry and ageing [113, 114]. A recent study by [PERSON] et al. [109] demonstrated that MPs incubated in Oder River water led to a significantly increased pathogen abundance and ARG prevalence in both water and sediment samples, confirming MPs as vectors for antimicrobial resistance in situ. Advances in nanoplastics research are revealing that particles <1 \(\upmu\)m can cross cell membranes, generate reactive oxygen species, and enhance horizontal gene transfer (HGT) within biofilms. For example, a review in 2024 documented increased ARG carriage on aged MPs due to enhanced surface roughness and chemical reactivity [115, 116]. In soil-based microcosms, the increased diversity of micro-/nanoplastics correlated with elevated ARG and mobile genetic element (MGE) abundance--highlighting emerging eco-toxicological pathways [117, 118, 119]. Although our work does not focus on nanoplastics or extreme settings, these recent developments--especially the spread of ARGs in remote or highly polluted environments--underscore the urgent need for integrated studies that combine MP characterization, ARG monitoring, and the evaluation of environmental risk in diverse ecosystems.