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What is Antimicrobial Resistance (AMR)?

What are antimicrobials?

Antimicrobials are drugs used to treat infections in humans and animals. Antimicrobials work by killing micro-organisms (bacteria, fungi, viruses, etc.) or stopping the growth of micro-organisms that cause infections. Antimicrobials include medicines such as antibiotics, antifungals and antivirals which are essential in protecting human and animal health, as well as animal welfare. 

What is antimicrobial resistance (AMR)?           

Antimicrobial resistance (AMR) occurs when micro-organisms that cause infections adapt and prevent an antimicrobial from working against it. As a result the antimicrobials used to treat infections are no longer effective, limiting the treatment options available and therefore making the most common infections more difficult to treat.

The terms antimicrobials and antibiotics are used interchangeably but generally when talking about AMR we are referring to bacterial resistance to antibiotics. 

The term antibiotic residue should not be confused with AMR. Antibiotic residue in food means that there are traces of antibiotics remaining in meat and milk derived from animals that have been treated with antibiotics. If a farmer adheres to the required withdrawal period for an antibiotic then no antibiotic residues will exist in these products. However, adhering to the withdrawal period does not prevent the development of antimicrobial resistance. The use of antibiotics over time will inevitably lead to bacteria becoming resistant and antibiotics becoming less effective. However the misuse and overuse of antimicrobials is accelerating this process.

More information on antimicrobial resistance can be found here.

Why is antimicrobial resistance (AMR) an issue?

It is unlikely that there will be any new classes of antibiotics available for many years. This poses a serious threat to disease control throughout the world. This is not only a global public health concern but it will also have consequences for animal health, food security and the environment. 

The discovery of antibiotics has revolutionised health care and prolonged life expectancy across the globe. Antibiotics have substantially reduced mortality from infectious diseases and have provided protection against infectious complications for many modern medical practices including surgery, neonatal care and cancer treatment. 

Antibiotics are also widely used in animal health. The availability and use of antibiotics is of vital importance in protecting animal health and welfare, productivity and facilitating the production of safe, nutritious food. If antibiotics lose their efficacy there will be a lack of suitable medicines that farmers can avail of to protect animal health and welfare. This will impact on farm productivity and profitability.

How does antimicrobial resistance (AMR) develop and spread?

The development of resistance is a natural phenomenon that will inevitably occur when antibiotics are used to treat infection. Every time antibiotics are used, bacteria are offered the opportunity to develop resistance.

Resistant bacteria can be transmitted between animals, humans and the environment so AMR is a problem for both animals and, more importantly, humans. 

In farming, animals treated with antibiotics can become potential sources of AMR. Resistant bacteria and antibiotic residues can be transmitted from these animals through animal manure spread across the land as fertiliser. This animal manure can be absorbed by food crops, thereby spreading resistant bacteria and antibiotic residues to humans through food. Large quantities of bacteria and antibiotic residues can also enter soil and groundwater from excreted animal urine and manure. Resistant bacteria can also be spread to humans through direct contact with animals. 

More information on how anti-microbial resistance spreads and develops can be found here.

What factors increase the development and spread of AMR?

The problem at present is that the continued use, particularly the inappropriate use of antibiotics in humans, animals and in other situations is leading to significant increases in the development and spread of AMR. 

The misuse of antibiotics may lead to the development and spread of AMR, for example:

  • Overuse of antibiotics
  • Under-dosing with antibiotics
  • Not finishing the treatment course
  • Incorrect disposal of antibiotics
  • Use of last resort antibiotics as first line therapy
  • Blanket use of antibiotics in an untargeted manner
  • Treatment of bacteria that are not susceptible to the particular antibiotic
  • Treatment of diseases caused by viruses or other germs not susceptible to antibiotics

What can be done at farm level to prevent AMR?

When it comes to animal health, prevention is better than cure. The first step farmers can take to prevent the development of AMR is to improve the overall health status of the animals on the farm. This will not only reduce antibiotic use on farm but it will also maximise farm productivity. This can be achieved through disease prevention strategies such as good biosecurity measures, adequate housing, optimal stocking densities, vaccination and parasite control. Under no circumstances should antibiotics be used to compensate for poor farm management practices. 

Antibiotics should be used to maintain animal health and welfare where necessary, in other words they should be used prudently. To use antibiotics prudently is to use them correctly. The six R’s should be followed when using antibiotics:

  1. Right Veterinary Diagnosis
  2. Right Animal
  3. Right Antibiotic
  4. Right Dose
  5. Right Duration
  6. Right Storage and Duration

More information regarding the prudent use of antibiotics can be found at the Code of Good Practice Regarding the Responsible Prescribing and Use of Antibiotics in Farm Animals.

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