Soil Microbial Communities and Antibiotic Resistance in Cattle Farms in the United States: The Importance of Soils in Protecting Environmental Health
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Date
2021-04
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Abstract
Cattle farming is a large and evolving industry in the United States (US) with potential health effects in workers, consumers, and individuals living in areas surrounding these operations. Because cattle farming inherently generates a large amount of manure, it is considered a major contributor to antibiotic resistant (AR) genes and bacteria in nearby environments. This study sought to quantify AR genes and pathogens in cattle-associated soils, as well as describe the associated microbial communities. Microbial communities and AR genes were compared in soils within and outside of cattle pens. Soil was sampled from seven cattle farms from different states in the United States. From each farm, one soil sample was taken from within the cattle pens and one sample was taken from outside of the pens. Following DNA extraction, bacterial communities were analyzed via 16S rRNA sequencing. Droplet Digital PCR and real-time PCR were used to quantify three enteric pathogens, three AR genes, and three host-specific microbial source tracking (MST) markers, which were used to identify sources of fecal pollution. The family Peptostreptococcaceae was more abundant in pen soils, and Rhodanobacteraceae was more abundant in non-pen soils. The marker for ruminant fecal contamination (Rum2Bac) was abundant both in pen and non-pen soils, with no significant difference. However, the concentration of the human fecal contamination marker (HF183) was lower in pen soils than non-pen soils. Soils from within cattle pens had higher levels of the pathogens Campylobacter and Salmonella (p<0.05). Cattle pen soils also had higher concentrations of two AR genes (p<0.05), Klebsiella pneumonia Carbapenemase (KPC) and sul1, which offers resistance to sulfonamide antibiotics. This is the first study identifying KPC in livestock-associated soils in the US, an AR gene of concern because it is clinically relevant and spreads easily between bacteria. This study supports increased hazard associated with livestock soils for animal and human health, as well as environmental quality.
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Poster Division: Food, Agricultural, and Environmental Sciences (FAES): 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
soil microbial community, cattle farm, microbial source tracking, carbapenem resistance, soil reservoir