Statewide Assessment of Iowa Streams Links Landscape Characteristics to Antibiotic Resistance Signatures
U.S. Geological Survey (USGS) scientists conducted the first statewide assessment of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistant genes (ARGs) in streams (water column and bed sediment samples) across Iowa. Results indicated that ARB and ARGs were prevalent, and a combination of watershed characteristics (such as land use, livestock population, and human population) were related to the antibiotic resistance signatures observed.
In the United States, antibiotics and antimicrobial pesticides are commonly used for human health and food production (for example, livestock, row crops, and orchards). It is now realized that the use of these chemicals provides the opportunity to generate antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) that are recognized as environmental contaminants of global concern.
In 2019, U.S. Geological Survey (USGS) researchers, along with scientists from the University of Iowa Center for Health Effects of Environmental Contamination, designed and conducted a stream assessment of water and bed sediment across Iowa to provide the most comprehensive investigation of antibiotics (n =31), ARB (n = 9), and ARGs (n = 24) in agricultural streams to date. Iowa was an ideal study area because 85 percent of its landscape is devoted to crop and livestock agriculture. Significant correlations between various watershed characteristics (such as livestock and human populations) and environmentally relevant ARB (such as methicillin-resistant Staphylococci aureus [MRSA]) were observed.
In addition to providing critical baseline data on ARB, ARGs, and antibiotics, this stream study determined the following: (1) high bacteria concentrations, ARB, and ARGs were prevalent in stream water and bed sediment, (2) ARG detections were more prevalent than antibiotics, and (3) watershed characteristics and hydrodynamics affect antibiotic resistance signatures. These study results indicate the importance of streambed sediment as an environmental reservoir for ARB and ARGs. Thus, the health risk potential for humans, wildlife, and livestock exposed to these streams is underestimated when only stream water is considered.
This research was funded by the USGS, Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology), the University of Iowa Center for Health Effects of Environmental Contamination, and the Chicago Community Foundation at the recommendation of The Builders Initiative.
U.S. Geological Survey (USGS) scientists conducted the first statewide assessment of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistant genes (ARGs) in streams (water column and bed sediment samples) across Iowa. Results indicated that ARB and ARGs were prevalent, and a combination of watershed characteristics (such as land use, livestock population, and human population) were related to the antibiotic resistance signatures observed.
In the United States, antibiotics and antimicrobial pesticides are commonly used for human health and food production (for example, livestock, row crops, and orchards). It is now realized that the use of these chemicals provides the opportunity to generate antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) that are recognized as environmental contaminants of global concern.
In 2019, U.S. Geological Survey (USGS) researchers, along with scientists from the University of Iowa Center for Health Effects of Environmental Contamination, designed and conducted a stream assessment of water and bed sediment across Iowa to provide the most comprehensive investigation of antibiotics (n =31), ARB (n = 9), and ARGs (n = 24) in agricultural streams to date. Iowa was an ideal study area because 85 percent of its landscape is devoted to crop and livestock agriculture. Significant correlations between various watershed characteristics (such as livestock and human populations) and environmentally relevant ARB (such as methicillin-resistant Staphylococci aureus [MRSA]) were observed.
In addition to providing critical baseline data on ARB, ARGs, and antibiotics, this stream study determined the following: (1) high bacteria concentrations, ARB, and ARGs were prevalent in stream water and bed sediment, (2) ARG detections were more prevalent than antibiotics, and (3) watershed characteristics and hydrodynamics affect antibiotic resistance signatures. These study results indicate the importance of streambed sediment as an environmental reservoir for ARB and ARGs. Thus, the health risk potential for humans, wildlife, and livestock exposed to these streams is underestimated when only stream water is considered.
This research was funded by the USGS, Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology), the University of Iowa Center for Health Effects of Environmental Contamination, and the Chicago Community Foundation at the recommendation of The Builders Initiative.