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United States Department of Agriculture

Agricultural Research Service

Research Project: Efficient Management and Use of Animal Manure to Protect Human Health and Environmental Quality

Location: Food Animal Environmental Systems Research Unit

Title: Detection of pathogens, indicators and antibiotic resistance genes following land application of poultry litter

Authors
item Cook, Kimberly
item Netthisinghe, A -
item Gilfillen, R -

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 22, 2014
Publication Date: July 25, 2014
Citation: Cook, K.L., Netthisinghe, A.M., Gilfillen, R.A. 2014. Detection of pathogens, indicators and antibiotic resistance genes following land application of poultry litter. Journal of Environmental Quality. 43:1546-1558.

Interpretive Summary: Large amounts of poultry litter (PL) are applied to soils each year. This PL is a valuable nutrient source for crop production however land application may be a route of plant, soil or water contamination with manure-associated bacteria. The objective of this study was to characterize the level of naturally occurring populations of pathogens, fecal indicator bacteria (FIB) and antibiotic resistance genes (ARG) following application of PL to soils under conventional or no till management under conditions representative of realistic agricultural practices. PL had high concentrations of total cells, FIB and ARG for sulfonamide, tetracycline and streptomycin and Campylobacter jejuni. Salmonella spp. could not be detected in initial manures, but was enriched periodically from amended soils suggesting that populations were responding to chemical and/or environmental factors. The common fecal indicator organism Escherichia coli only occurred in low concentrations in PL and could not be detected in field soils. These results suggest that enterococci may be better indicators of fecal contamination from field applied PL. Within one to two days of PL application concentrations of ARG for sulfonamide and tetracycline resistance increased two orders of magnitude and remained above background for the duration of the study. These data provide new knowledge about important microbial FIB, pathogens and ARG under realistic field-based conditions.

Technical Abstract: The United States (U.S.) is the world’s largest producer of poultry with over 18,000 kg of poultry litter (PL), a mixture of poultry manure, bedding, feathers, and spilled feed produced as a by-product. This PL is a valuable nutrient source for crop production however; land application of livestock manures without prior treatment and/or in areas with intensive animal production may be a route of plant, soil or water contamination with manure-associated bacteria. The objective of this study was to characterize the level of naturally occurring populations of pathogens, fecal indicator bacteria (FIB) and antibiotic resistance genes (ARG) following application of PL to soils under conventional or no till management. This two year study was conducted in accordance with normal agricultural practices and microbial populations were quantified using a combination of culture and quantitative, real-time (qPCR) analyses. PL had high concentrations of total cells, FIB and ARG for sulfonamide, tetracycline and streptomycin. Initial concentrations of Campylobacter jejuni in poultry litter were 5.4 ±3.2 X 10e6 cells per gram, while enterococci averaged 5.7 ±0.7 X 10e6 cells per gram. Salmonella spp. could not be detected in initial manures, but was enriched periodically from amended soils suggesting that populations were responding to chemical and/or environmental factors. The common fecal indicator organism Escherichia coli only occurred in low concentrations in PL and could not be detected in field soils. These results suggest that enterococci may be better indicators of fecal contamination from field applied PL. Within one to two days of PL application concentrations of ARG for sulfonamide and tetracycline resistance increased two orders of magnitude and remained above background for the duration of the study. These data provide new knowledge about important microbial FIB, pathogens and ARG under realistic field-based conditions.

Last Modified: 11/27/2014
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