Location: Agroecosystem Management Research
Title: Co-occurrence of antibiotic drugs, resistant bacteria and resistance genes in runoff from cattle feedlots Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 18, 2014
Publication Date: N/A
Interpretive Summary: The use of antibiotics in food animals raises concerns that antibiotic resistance might be transferred from animals to humans. One route by which this is thought to possibly occur is when rain water carries residues from animal manures into surface or ground water supplies. There are few examples from the literature of off-site losses of both antibiotics and antibiotic resistance genes. There are three main parts involved in tracking agricultural antibiotic resistance: the antibiotic drugs, the resistant bacteria, and the DNA instructions inside the bacteria that code for resistance (the resistance genes). Previous studies generally examine either the chemical (antibiotic drug) or biological (resistant bacteria and genes) elements of resistance in the environment. In this investigation, we evaluated the co-occurrence of antibiotic compounds, resistant bacteria, and resistance genes from beef cattle feedlot runoff, applied to vegetative strips of cool-season grasses. Results from this study support the importance of designing irrigation systems for land application of manures that minimize runoff in order to limit environmental release of antibiotics and potential for proliferation of antibiotic resistance.
Technical Abstract: Agricultural uses of antibiotics raises concerns about the development of antibiotic resistance in food animals, and the potential to transmit resistance to human clinical settings via fecal contamination of surface and ground water. Although there is broad agreement that agricultural resistance can be transferred from animals to humans, the ecology of resistance in agroecosystems, and the specific details of transmission remain unclear. In addition, little information is available that links the chemical and biological components of resistance in applied agricultural settings. We determined the co-occurrence of selected antibiotic compounds, resistant fecal bacteria, and resistance genes from beef cattle feedlot runoff, applied to vegetative strips of cool-season grasses. A suite of antibiotics were measured, tetracycline resistant and cefotaxime resistant bacteria were enumerated, and isolates were screened for resistance to twelve antibiotics. The majority of the runoff isolates contained resistance to at least one antibiotic, with some individual isolates demonstrated resistance to multiple antibiotics. These data support the importance of managing feedlot surface run-off, and for designing irrigation systems for land application of manures that minimize runoff to minimize environmental release of antibiotic resistance.