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. 2019 Feb 15;14(2):e0212510.
doi: 10.1371/journal.pone.0212510. eCollection 2019.

Persistence of antibiotic resistance genes in beef cattle backgrounding environment over two years after cessation of operation

Getahun E Agga  1 , Kimberly L Cook  1 , Annesly M P Netthisinghe  2 , Rebecca A Gilfillen  2 , Paul B Woosley  2 , Karamat R Sistani  1
Affiliations

Persistence of antibiotic resistance genes in beef cattle backgrounding environment over two years after cessation of operation

Getahun E Agga et al. PLoS One. .

Abstract

Confined animal feeding operations can facilitate the spread of genes associated with antibiotic resistance. It is not known how cattle removal from beef cattle backgrounding operation affects the persistence of antibiotic resistance genes (ARGs) in the environment. We investigated the effect of cessation of beef cattle backgrounding operation on the persistence and distribution of ARGs in the beef cattle backgrounding environment. The study was conducted at a pasture-feedlot type beef cattle backgrounding operation which consisted of feeding and grazing areas that were separated by a fence with an access gate. Backgrounding occurred for seven years before cattle were removed from the facility. Soil samples (n = 78) from 26 georeferenced locations were collected at the baseline before cattle were removed, and then one year and two years after cattle were removed. Metagenomic DNA was extracted from the soil samples and total bacterial population (16S rRNA), total Enterococcus species and class 1 integrons (intI1), and erythromycin (ermB and ermF), sulfonamide (sul1 and sul2) and tetracycline (tetO, tetW and tetQ) resistance genes were quantified. Concentrations of total bacteria, Enterococcus spp., class 1 integrons, and ARGs were higher in the feeding area and its immediate vicinity (around the fence and the gate) followed by a gradient decline along the grazing area. Although the concentrations of total bacteria, Enterococcus spp., class 1 integrons and ARGs in the feeding area significantly decreased two years after cattle removal, their concentrations were still higher than that observed in the grazing area. Higher concentrations over two years in the feeding area when compared to the grazing area suggest a lasting effect of confined beef cattle production system on the persistence of bacteria and ARGs in the soil.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Georeferenced soil sampling locations at beef cattle backgrounding environment monitored for the persistence of antibiotic resistance genes for two years after cessation of operation.
The facility was divided into feeding (FD) and grazing (GR) areas separated by a fence.
Fig 2
Fig 2. Spatial distributions of total bacteria, total Enterococcus species and integrase gene of class 1 integrons in beef cattle backgrounding environment over two years period after cattle removal.
Fig 3
Fig 3. Spatial distributions of erythromycin resistance gene (ermB and ermF) concentrations in beef cattle backgrounding environment over a period of two years after cattle removal.
Fig 4
Fig 4. Spatial distributions of two sulfonamide resistance genes (sul1 and sul2) concentrations in beef cattle backgrounding environment over two years after cattle removal.
Fig 5
Fig 5. Spatial distributions of three tetracycline resistance genes (tetO, tetW and tetQ) concentrations in beef cattle backgrounding environment over a two years period after cattle removal.
See this image and copyright information in PMC

References

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