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

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 ( int I1), and erythromycin ( erm B and erm F), sulfonamide ( sul 1 and sul 2) and tetracycline ( tet O, tet W and tet Q) 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.

Microbial load and antibiotic resistance in raw beef preparations from northwest Spain

“…Along these lines, some years ago it was demonstrated that the use of antibiotics modifies the resistance genes present in bacterial communities (the resistome). The effects on this set of genes persist for years even in the absence of any contact with antibiotics (Agga et al, ; Johnsen et al, ; Sommer & Dantas, ). Smith et al () found that successive exposures to antibiotics create a resistance that is stable over time and that resistant strains can compete with susceptible strains even when there is no selective pressure.…”

Swine liquid manure: a hotspot of mobile genetic elements and antibiotic resistance genes

“…Antibiotic resistance genes (ARGs), as emerging contaminants, play an important role in antibiotic resistance 6 via various mechanisms, including enzymes that degrade or modify the antibiotic, modification of cell components like cell wall and ribosomes, and finally efflux pumps that could confer multiple resistance to bacteria 7 . Numerous studies have demonstrated that ARGs and antibiotic resistant bacteria (ARB) occurred in various farm wastes like animal feces 8 – 10 and livestock wastewater 11 – 13 . Unfortunately, the land fertilization of livestock manure may introduce ARGs and pathogenic bacteria to farmland soil 14 – 16 , groundwater and surface water in the surrounding environment 17 , 18 .…”

Fecal cultivable aerobic microbiota of dairy cows and calves acting as reservoir of clinically relevant antimicrobial resistance genes

“…Some factors can contribute to transmission of antimicrobial-resistant bacteria and ARGs to humans, such as the contact with animals or the food chain [31]. Besides, antimicrobial-resistant bacteria that do not persist in the environment (i.e., soil and water) may transfer ARGs to resident soil bacteria [4,32]. Some of ARGs found have been intrinsically described in Gram-negative and Gram-positive bacteria.…”