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The global spread of antibiotic resistance genes (ARGs) in the marine environment poses a significant threat to public health and natural ecosystems. This study quantified and analysed the distribution and co-occurrence patterns of ARGs in a wide range of oceans and high seas, including the Atlantic, Arctic and Indian Ocean, the Mediterranean Sea and the Persian Gulf. Focusing on beta-lactamases ( bla OXA-48 , bla CTX-M-1 group , and bla TEM ), sulfonamides ( sul 1) and tetracycline ( tet A), our results showed that sul 1 was ubiquitous, indicating widespread dissemination. Notably, the Mediterranean Sea exhibited higher levels of multiple ARGs in single samples, suggesting significant anthropogenic impact. Interestingly, the Arctic Ocean, particularly around the Svalbard Islands, also showed the presence of multiple ARGs, highlighting the pervasive occurrence of antibiotic resistance in remote areas. We employed two clustering approaches to explore ARG patterns, primarily focusing on identifying geographic trends and differences in ARG abundance. Additionally, we investigated potential sources of contamination, including proximity to wastewater treatment plants, ports, marine traffic, and currents. These findings clearly demonstrate that antibiotic resistance gene contamination is widespread across diverse marine environments, with significant regional variations. This underscores the urgent need for tailored intervention strategies and global collaboration to mitigate the spread of ARGs and manage their complex dynamics in marine ecosystems. • Novel pentaplex digital PCR assay enhances precise detection of multiple ARGs. • Global analysis reveals widespread ARGs in marine environments, including remote regions. • High ARGs contamination found in the Mediterranean Sea and Arctic Ocean near Svalbard • Two clustering methods show 51 % concordance in classifying ARG contamination levels. • Potential contamination hotspots linked to human activities found in marine ecosystems
Ferraro et al. (Thu,) studied this question.