Antibiotic Resistance Genes in Interconnected Surface Waters as Affected by Agricultural Activities

• Published in: Biomolecules (Basel, Switzerland) Vol. 13; no. 2; p. 231
• Main Authors: Zhao, Beilun, van Bodegom, Peter M., Trimbos, Krijn B.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24.01.2023; MDPI
• Subjects: agricultural area; Agricultural products; Agriculture; Anti-Bacterial Agents - pharmacology; Antibiotic resistance; antibiotic resistance genes; Antibiotics; Bacteria; co-occurrence; Dissolved oxygen; Drug resistance; Drug resistance in microorganisms; Drug Resistance, Microbial; Environmental aspects; environmental pollution; Food sources; Gene transfer; Genes; Genes, Bacterial; Genetic aspects; greenhouse; Greenhouses; Health risk assessment; Health risks; Horizontal transfer; Horticulture; Humans; Livestock; Microbial genetics; Microbiological research; Microorganisms; Pasture; Pastures; Physiological aspects; Public health; Sediments; Sulfonamides; Sulfonamides - pharmacology; Netherlands; Europe; agricultural area; intl1 gene; co-occurrence; environmental pollution; greenhouse; antibiotic resistance genes; pasture
• DOI: 10.3390/biom13020231
• ISSN: 2218-273X

Pastures have become one of the most important sources of antibiotic resistance genes (ARGs) pollution, bringing risks to human health through the environment and the food that is grown there. Another significant source of food production is greenhouse horticulture, which is typically located near pastures. Through waterways, pasture-originated ARGs may transfer to the food in greenhouses. However, how these pasture-originated ARGs spread to nearby waterways and greenhouses has been much less investigated, while this may pose risks to humans through agricultural products. We analyzed 29 ARGs related to the most used antibiotics in livestock in the Netherlands at 16 locations in an agricultural area, representing pastures, greenhouses and lakes. We found that ARGs were prevalent in all surface waters surrounding pastures and greenhouses and showed a similar composition, with sulfonamide ARGs being dominant. This indicates that both pastures and greenhouses cause antibiotic resistance pressures on neighboring waters. However, lower pressures were found in relatively larger and isolated lakes, suggesting that a larger water body or a non-agricultural green buffer zone could help reducing ARG impacts from agricultural areas. We also observed a positive relationship between the concentrations of the class 1 integron (intl1 gene)—used as a proxy for horizontal gene transfer—and ARG concentration and composition. This supports that horizontal gene transfer might play a role in dispersing ARGs through landscapes. In contrast, none of the measured four abiotic factors (phosphate, nitrate, pH and dissolved oxygen) showed any impact on ARG concentrations. ARGs from different classes co-occurred, suggesting simultaneous use of different antibiotics. Our findings help to understand the spatial patterns of ARGs, specifically the impacts of ARGs from pastures and greenhouses on each other and on nearby waterways. In this way, this study guides management aiming at reducing ARGs′ risk to human health from agricultural products.