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United States Department of Agriculture

Agricultural Research Service

Research Project: ENVIRONMENTALLY SOUND MANURE MANAGEMENT FOR REDUCTION OF GAS EMISSIONS, NUTRIENTS, AND PATHOGENS

Location: Agroecosystem Management Research

Title: Fate of antimicrobials and antimicrobial resistance genes in simulated swine manure storage

Authors
item Joy, Stacey -
item Li, Xu -
item Snow, Daniel -
item Gilley, John
item Woodbury, Bryan
item Bartlett-Hunt, Shannon -

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 2014
Publication Date: February 28, 2014
Repository URL: http://handle.nal.usda.gov/10113/58956
Citation: Joy, S.R., Li, X., Snow, D.D., Gilley, J.E., Woodbury, B.L., Bartlett-Hunt, S.L. 2014. Fate of antimicrobials and antimicrobial resistance genes in simulated swine manure storage. Science of the Total Environment. 481:69-74. Available: http://dx.doi.org/10.1016/j.scitotenv.2014.02.027.

Interpretive Summary: The behavior of three antibiotics (bacitracin, chlortetracycline, and tylosin) and two classes of antibiotic resistance genes (tet and erm) were monitored in swine manure slurry under laboratory conditions. Half-lives ranged from 1 day for chlortetracycline to 10 days for tylosin. Antibiotic resistance genes were monitored in the swine manure slurry, and losses of 1 to 3 orders of magnitude were observed. Tylosin was degraded to approximately 10% of the starting concentration by day 40; however, the relative abundance of the antibiotic resistance genes remained at 50-60% of the initial relative abundance. These results indicate that tet resistance genes respond primarily to tetracycline antimicrobials, and may be lost when the parent tetracycline compound is degraded. In contrast, erm antibiotic resistance genes may respond to a range of antimicrobials in animal manure, and may persist despite losses of tylosin.

Technical Abstract: The behavior of three antibiotics (bacitracin, chlortetracycline, and tylosin) and two classes of antibiotic resistance genes (ARGs), tet and erm, were monitored in swine manure slurry under anaerobic conditions. First-order decay rates were determined for each antibiotic with half-lives ranging from 1 day (chlortetracycline) to 10 days (tylosin). ARGs were monitored in the swine manure slurry, and losses of 1 to 3 orders of magnitude were observed during the 40 day storage period. First-order degradation profiles were observed for chlortetracycline and its corresponding resistance genes, tet(X) and tet(Q). Tylosin was degraded to approximately 10% of the starting concentration by day 40; however, the relative abundance of the erm(B) remained at 50-60% of the initial relative abundance. These results indicate that tet resistance genes respond primarily to tetracycline antimicrobials, and may be lost when the parent tetracycline compound is degraded. In contrast, erm ARGs may respond to a range of antimicrobials in animal manure, and may persist despite losses of tylosin.

Last Modified: 10/30/2014
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