Antibiotic Measurement and Recovery in Manure and Impacts on Antimicrobial Resistance in Agricultural Settings

Antimicrobial resistance (AMR) has been exacerbated through anthropogenic sources of antibiotics, with antibiotics use in animal production being a possible contributor to AMR. On dairy and beef cattle operations, different classes of antibiotics are administered in response to an infection, or as a prophylactic to prevent infection. The connection between cattle antibiotic use and AMR development in human pathogens is uncertain. To better understand this possible connection (and associated risks), we need improved knowledge of the fate and transport of antibiotics in livestock manure. This necessitates quantification of antibiotics in complex organic matrices. The challenges in measuring antibiotics in animal husbandry result from the heterogeneity of manure with varying manure treatment and handling systems. Typically, antibiotic extraction procedures focus on a single class of antibiotic; however, the goal of this study was to optimize one extraction method for multiple classes of antibiotics in cattle manure. Four classes of antibiotics were targeted: tetracyclines, macrolides, sulfonamides, and beta-lactams. The beta-lactams, penicillin G, ampicillin, ceftiofur, and two lactam metabolites were of specific interest because of their prevalent use for treatment and prevention of mastitis in dairy cows and difficulty to detect in manure extracts. Two manure preservation methods were considered: frozen and freeze-dried. Tested extraction methods included: accelerated solvent extraction, liquid-liquid extraction, solid phase extraction, and salting out. None of the direct extraction procedures produced sufficient recoveries for the beta-lactams. A derivatization method that hydrolyzed the beta-lactam group with piperidine prior to extraction improved recoveries. Antibiotic extraction efficiencies from cattle manure, determined using reverse phase HPLC tandem MS-MS analyses after preservation and extraction, will be presented in full.



Andrea Yarberry, Beltsville Agricultural Research Center, ORISE Participant, United States Department of Agriculture,

Rice, Clifford (Agricultural Research Center, Sustainable Agricultural Systems Laboratory, United States Department of Agriculture, Beltsville, MD, USA); Poindexter, Carlton (Department of Environmental Science and Technology, University of Maryland, College Park, MD, USA); Lansing, Stephanie (Department of Environmental Science and Technology, University of Maryland, College Park, MD, USA)


This research was supported in part by an appointment to the Agricultural Research Service (ARS) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA). ORISE is managed by ORAU under DOE contract number DE-SC0014664. All opinions expressed in this paper are the author’s and do not necessarily reflect the policies and views of USDA, ARS, DOE, or ORAU/ORISE.


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