Exploring the Animal Waste Resistome: The Spread of Antimicrobial Resistance Genes Through the Use of Livestock Manure

Abstract

Antibiotic resistance is a public health problem of growing concern. Animal manure application to soil is considered to be a main cause of the propagation and dissemination of antibiotic residues, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in the soil-water system. In recent decades, studies on the impact of antibioticcontaminated manure on soil microbiomes have increased exponentially, in particular for taxonomical diversity and ARGs' diffusion. Antibiotic resistance genes are often located on mobile genetic elements (MGEs). Horizontal transfer of MGEs toward a broad range of bacteria (pathogens and human commensals included) has been identified as the main cause for their persistence and dissemination. Chemical and bio-sanitizing treatments reduce the antibiotic load and ARB. Nevertheless, effects of these treatments on the persistence of resistance genes must be carefully considered. This review analyzed the most recent research on antibiotic and ARG environmental dissemination conveyed by livestock waste. Strategies to control ARG dissemination and antibiotic persistence were reviewed with the aim to identify methods for monitoring DNA transferability and environmental conditions promoting such diffusion.

A Large Spatial Survey of Colistin-Resistant Gene mcr-1-Carrying E. coli in Rivers across Taiwan

“…Following population expansion, such bacteria may be released from the animals and reach and contaminate nearby rivers. Conventional livestock waste treatment processes cannot completely remove antibiotic-resistance genes, and result in contamination of water environments [ 52 , 53 ]. Some studies have reported the transmission of antimicrobial-resistant bacteria from pig manure to the environment [ 54 ], and these antibiotic-resistant bacteria may spread through water [ 55 ].…”

Manure Microbial Communities and Resistance Profiles Reconfigure after Transition to Manure Pits and Differ from Those in Fertilized Field Soil

“…This is especially interesting because we might expect the selective pressures in the mammalian gut that enrich ARGs to be decreased in environmental settings. Lack of ARG depletion suggests that either ARGs are maintained outside the gut, possibly by stable plasmids or by selective pressures from the excreted antimicrobials that are not metabolized, or ARGs are introduced to the manure pits from sources other than the dairy cow gut (18,30,32). Further, we found a reconfiguration in the composition of ARGs, with specific ARGs being enriched in either fresh manure or manure pits and an increase in beta diversity between fresh manure and manure pits.…”

“…However, the introduction of microbiota from the guts of animals may have adverse effects on the microbial composition and functional resistance profiles found in the environment. Past studies suggest that antimicrobial resistance may remain on farms through the acquisition of multidrug resistance and horizontal gene transfer, but it is unclear how much antimicrobial resistance spreads to fields and how that spread influences microbial composition and the total amount and diversity of functional ARGs, known as the resistome of manure and soil (30)(31)(32). Further, most studies focus on known or individual antimicrobial resistance genes of interest, missing less characterized antimicrobial genes that may be of equal concern (7)(8)(9)(10)(11)(12).…”

Taking a lesson from the COVID-19 pandemic: Preventing the future outbreaks of viral zoonoses through a multi-faceted approach

“…Importantly, the risk of the emergence and rapid spread of livestock pathogens (such as the ASF virus) that are a threat to food security is non-existent in the case of cultured meat. Secondly, the production of cultured meat would decrease the excessive use of antibiotics that promote the emergence and spread of antibiotic-resistant bacteria ( Checcucci et al, 2020 ; He et al, 2020 ). Thirdly, the production process is much more predictable and less time-consuming with several weeks needed for the conversion of nutrients and energy instead of the months or years needed in the case of meat originating from livestock ( Bhat et al, 2015 ).…”