A groundbreaking study published in Science of The Total Environmenthttps://www.sciencedirect.com/science/article/pii/S0048969725023666 investigates the presence and distribution of antimicrobial resistance genes (ARGs) in sea surface aerosols across the Atlantic Ocean, shedding light on the ocean’s potential role as a reservoir for antibiotic resistance. Conducted during a 22-day transatlantic cruise from Brest, France, to Woods Hole, USA, in December 2021, the research analyzed aerosol samples collected from a sailing vessel to assess bacterial loads, microbial diversity, and ARGs.
The study utilized two sampling methods: 24-hour integrative sampling to capture broad trends and one-hour spot sampling to detect short-term variations. Using quantitative PCR (qPCR), researchers monitored 21 ARG subtypes representing major antibiotic resistance families, alongside bacterial diversity assessed through 16S rRNA gene sequencing. Air mass origins were traced using atmospheric dynamics models to understand their influence on ARG distribution.
Findings revealed significant variability in ARG concentrations, ranging from a few copies to over 105 copies per cubic meter of air. Near coastal areas, macrolide and tetracycline resistance genes dominated, likely reflecting terrestrial influences such as agricultural or human-related activities. Further offshore, sulfonamide resistance genes were prevalent, while transposase and ?-lactamase genes appeared sporadically. Notably, quinolone resistance genes, particularly qepA, were widespread over the open ocean, suggesting marine surfaces as a significant source of ARGs. This was supported by correlations between ARGs and marine microorganisms, including cyanobacteria, indicating the ocean’s role in disseminating resistance through aerosols.
The study also highlighted the influence of continental air masses, with soil-derived microorganisms detected in aerosols, pointing to long-distance transport of ARGs from land. The interplay of marine and terrestrial sources underscores the complexity of ARG spread, with marine surfaces potentially acting as both reservoirs and vectors for global dissemination via atmospheric pathways. These findings emphasize the need for further research to distinguish source contributions and address the environmental and health implications of airborne ARGs, particularly in the context of global antibiotic resistance.
