page_title: Antibiotic use in livestock
section_title: Mechanisms for the development of resistance
hierarchical_section_title: Antibiotic use in livestock / Antibiotic resistance / Mechanisms for the development of resistance
caption_attribution_description: English: Bacterial cell division depicting daughter cells receiving both a copy of the chromosome and a copy of a plasmid.
context_page_description: Antibiotic use in livestock is the use of antibiotics for any purpose in the husbandry of livestock, which includes treatment when ill, treatment of a group of animals when at least one is diagnosed with clinical infection, and preventative treatment. Antibiotics are an important tool to treat animal as well as human disease, safeguard animal health and welfare, and support food safety. However, used irresponsibly, this may also have impacts on human, animal and environmental health in a One Health context, as up to 90% of the antibiotic parent compounds can be directly excreted and this can lead to antibiotic resistance developing in the environment. While levels of use vary dramatically from country to country, for example some Northern European countries use very low quantities to treat animals compared with humans, worldwide an estimated 73% of antimicrobials are consumed by farm animals. Furthermore, a 2015 study also estimates that global agricultural antibiotic usage will increase by 67% from 2010 to 2030, mainly from increases in use in developing BRIC countries.
context_section_description: Antibiotic resistance - often referred to as antimicrobial resistance (AMR) although this term covers anti-virals, anti-fungals and other products - can occur when antibiotics are present in concentrations too low to inhibit bacterial growth, triggering cellular responses in the bacteria that allow them to survive. These bacteria can then reproduce and spread their antibiotic-resistant genes to other generations, increasing their prevalence and leading to infections that cannot be healed by antibiotics. This is a growing matter of concern as antibiotic resistance is considered to be a serious future threat to human welfare. Infectious diseases are the third leading cause of death in Europe and a future without effective antibiotics would fundamentally change the way modern medicine is practised. 
  Bacteria can alter their genetic inheritance through two main ways, either by mutating their genetic material or acquiring a new one from other bacteria. The latter being the most important for causing antibiotic-resistant bacteria strains in animals and humans. One of the methods bacteria can obtain new genes is through a process called conjugation which deals with transferring genes using plasmids. These conjugative plasmids carry a number of genes that can be assembled and rearranged, which could then enable bacteria to exchange beneficial genes among themselves ensuring their survival against antibiotics and rendering them ineffective to treat dangerous diseases in humans, resulting into multi-drug resistant organisms.
  However, it is important to note that antibiotic resistance also occurs naturally, as it is a bacterium's response to any threat. As a result, antibiotic-resistant bacteria have been found in pristine environments unrelated to human activity such as in the frozen and uncovered remains of woolly mammoths, in the polar ice caps and in isolated caves deep underground.
caption: Bacterial conjugation
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