|WILLIAMS-NGUYEN, JESSICA - University Of Washington|
|SALLACH, BRETT - University Of Nebraska|
|BARTELT-HUNT, SHANNON - University Of Nebraska|
|BOXALL, ALISTAIR - University Of York|
|MCLAIN, JEAN - University Of Arizona|
|SINGER, RANDALL - University Of Minnesota|
|SNOW, DANIEL - University Of Nebraska|
|ZILLES, JULIE - University Of Illinois|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2015
Publication Date: 3/1/2016
Citation: Williams-Nguyen, J., Sallach, B.J., Bartelt-Hunt, S., Boxall, A.B., Durso, L.M., Mclain, J.E., Singer, R.S., Snow, D.D., Zilles, J.L. 2016. Antibiotics and antibiotic resistance in agroecosystems: State of the science. Journal of Environmental Quality. 45(2):394-406.
Interpretive Summary: We propose a model to describe how antibiotic drugs, resistant bacteria, and resistance genes move through farms and the environment, and how they might impact human health. One important part of the model is to examine the relationships between drugs, bacteria, genes, and the natural ecosystem. For each step in the model – from antibiotic use on farm to untreatable human disease in the hospital, the available scientific evidence is examined, and knowledge gaps are highlighted. In general, we lack precise numbers of people who are exposed to environmental bacteria, including a lack of information on precise numbers of people exposed to antibiotic resistant bacteria. Without these numbers, it is difficult to accurately assess the human health effects of environmental resistance. We know that bacteria can share the DNA instructions for antibiotic resistance, but we do not know how often this happens, or the conditions that make it more likely for pathogens to acquire these instructions. Existing research has focused heavily on human health effects, with relatively little known about the effects of antibiotics and antibiotic resistance on natural and agricultural ecosystems. The proposed model is used to highlight gaps in knowledge that must be addressed by the research community and may provide a useful starting point for the design and analysis of future research.
Technical Abstract: We propose a simple causal model depicting relationships involved in dissemination of antibiotics and antibiotic resistance in agroecosystems and potential effects on human health, functioning of natural ecosystems, and agricultural productivity. Available evidence for each causal link is briefly summarized, and key knowledge gaps are highlighted. A lack of quantitative estimates of human exposure to environmental bacteria, in general, and antibiotic-resistant bacteria, specifically, is a significant data gap hindering the assessment of effects on human health. The contribution of horizontal gene transfer to resistance in the environment and conditions that might foster the horizontal transfer of antibiotic resistance genes into human pathogens also need further research. Existing research has focused heavily on human health effects, with relatively little known about the effects of antibiotics and antibiotic resistance on natural and agricultural ecosystems. The proposed causal model is used to elucidate gaps in knowledge that must be addressed by the research community and may provide a useful starting point for the design and analysis of future research efforts.