Antimicrobial Resistance: Answers to Commonly Asked Questions
What are "antibiotics" and "antimicrobial agents"?
- Antibiotic and antimicrobial are terms often used interchangeably, although there is a difference.
- Antibiotics are a type of antimicrobial agent produced from a mold or bacterium designed to kill, or slow the growth of bacteria.
- Antimicrobial agents (antimicrobials) are natural or synthetic substances that kill or inhibit the growth of microorganisms but cause little or no toxicity when administered to the animal. They capture a broad category of drugs, chemicals and other substances which include antibiotic drugs, antiviral agents, antifungal agents and antiparasitic drugs.
Why are antimicrobials used in animal agriculture?
- Antimicrobials have been used in animal agriculture since the early 1950's to prevent and treat disease and improve feed efficiency.
- Antimicrobials serve an important role in reducing the incidence of infectious bacterial disease which in turn assures the health and well-being of the animal.
- Our plentiful, reliable and affordable source of meat, fish, milk, eggs and honey is largely a result of the high health status of animals on Canadian farms.
What is antimicrobial resistance?
- Antimicrobial resistance is the ability of certain bacteria, which are normally destroyed by a particular antimicrobial, to survive exposure to that antimicrobial.
How can antimicrobial resistance occur?
Antimicrobial resistance can occur in 2 ways:
- Intrinsic Resistance occurs when a bacterium has an innate or naturally occurring resistance to certain antimicrobials.
- Acquired Resistance is where a susceptible bacterium acquires resistance either through genetic mutation or acquisition of resistance genes from another bacterium.
Why do producers use antimicrobials?
The use of antimicrobials in animal agriculture serves three purposes:
- Treatment of Disease – this typically involves the therapeutic treatment of individual animals, herds and/or flocks. Doses are for short periods of time to treat an active infection.
- Prevention of Illness – antimicrobials may be administered in low doses (sometimes called sub-therapeutic) at stressful periods of time in an animal’s production cycle to prevent and control disease.
- Production Enhancement (sometimes called growth promotion) - certain antimicrobials have been shown to prevent bacterial disease and improve feed efficiency. The World Health Organization has agreed with reports indicating that the use of antibiotics to improve nutritional efficiency results in reduced waste product output. These antibiotics have been proven to create a more favorable condition in the animal’s gut (intestine) for the digestion of feed allowing additional nutrient absorption. Another benefit is that they offer the animal a greater resistance to intestinal disease. Producers use these products judiciously and only at specific times in the production cycle.
What is the difference between therapeutic and subtherapeutic use?
- Veterinarians and food animal producers use therapeutic doses of antimicrobials for short periods of time to treat an active infection.
- Certain antimicrobials may be used at sub-therapeutic or low levels to prevent and control disease. Others may be used to enhance production through improved feed efficiency.
- All antimicrobials must meet Health Canada’s strict requirements for animal and human safety. Producers must document all antimicrobial use and follow strict withdrawal procedures as part of their on-farm food safety program.
What is the animal pharmaceutical industry doing about the issue of antimicrobial resistance in farm animals?
- Any licensed product sold to veterinarians / farmers by the pharmaceutical industry must meet Health Canada’s strict requirements for human and animal safety. A major component of Health Canada’s risk assessment for antimicrobials involves examining their likelihood to develop resistance.
- Manufacturers and sponsors of antimicrobials must conduct numerous studies on a product demonstrating its safety prior to being issued a license to sell the product. Major components of the studies address the potential for development of resistance. If resistance patterns are seen in the product development stage, it is not even submitted for regulatory approval.
- CAHI shares antimicrobial use data with Health Canada’s Canadian Integrated Program on Antimicrobial Resistance Surveillance (CIPARS) which monitors bacteria and resistance patterns on-farm, at processing and in retail establishments. We are committed to ensuring that only the safest, most efficacious products are sold by CAHI members.
What are farmers and veterinarians doing about the issue of antimicrobial resistance in farm animals?
- Farmers participate in HACCP-based (Hazard Analysis Critical Control Point) Quality Assurance programs, which promote proper and effective use of all animal health products, including antimicrobials.
- These programs stress the importance of a strong working relationship between producers and their veterinarians. They teach efficient management practices and emphasize proper drug use as a way of improving the safety of the food supply.
- Veterinarians play a crucial role in the judicious use of animal health products, including antimicrobials. They keep detailed records on the animals and herds they treat. This patient history helps them choose effective and safe therapies.
- Farmers and veterinarians participate in the Canadian Integrated Program on Antimicrobial Resistance Surveillance (CIPARS) which monitors bacteria and resistance patterns on-farm, at processing and retail. This surveillance will assist the Public Health Agency of Canada at detecting patterns of resistance and potentially lead to a better understanding of the cause of resistance.
- Farmers implement disease preventative strategies such as biosecurity, appropriate animal husbandry (such as ventilation), hygiene and routine health monitoring (including vaccination programs) to help decrease the need for antimicrobials.
- In some cases, antimicrobials are also used as a tool to help farmers manage disease. Medications are expensive, and should not be used to replace good management.
- The processing, retail and food service industries are also implementing programs to help eliminate harmful bacteria.
What are antimicrobial residues and how are they monitored?
- Residues are trace amounts of an antimicrobial or its break-down products (called metabolites) remaining in meat, fish, milk, eggs or honey produced from treated animals.
- Health Canada has established levels of residues that are considered safe and may legally be found in food. Provincial regulators monitor the milk supply and any producer found in violation is fined and the milk is destroyed. The Canadian Food Inspection Agency randomly tests meat at processing facilities to ensure all meat is free of harmful residues.
Do antimicrobial residues increase the risk of developing antimicrobial resistance?
- No. Antimicrobial residues and antimicrobial resistance are often confused but they are not related.
- When talking about the transfer of antimicrobial resistance from animals to humans (or vice-versa), scientists and others are referring to the transfer of resistant bacteria, not trace levels of antimicrobials.
What is being done by industry to reduce the risk of food-borne bacterial illness?
- Everyone in the food chain is working towards reducing the presence of bacteria on food.
- Livestock Producers are involved in on-farm Quality Assurance Programs based on the HACCP (Hazards Analysis Critical Control Point) program. Once enrolled in the program, they must meet a set of national standards. Just some of these include establishing and following protocols for barn sanitation, feed mixing, medication use and injection techniques as well as keeping specific records on feeds and medications used on-farm.
- Processors are also heavily involved in minimizing the risk of food-borne bacterial illness through HACCP-based programs. In all federal processing plants, veterinarians employed by the Canadian Food Inspection Agency are responsible for examining all carcasses for any signs of disease or abnormality. Random testing for residues is also a component of the processing industry’s quality assurance program. Extreme care is taken to avoid any bacterial contamination of meat in the processing plant.
- Retailers and the Food Service industry are the final links in the food chain’s strategy to minimize the risk of food-borne bacterial illness. Every effort is taken to avoid bacterial contamination in the retail meat case and in restaurants. They too work with producers and processors to ensure that every precaution is taken to minimize the risk of bacterial contamination.
What can I do to reduce the risk of food-borne bacterial illness?
- There are plenty of steps that consumers can take to reduce the risk of food-borne bacterial illness. Because bacteria are naturally present in food, it is important to carefully prepare, handle and store food.
- Thorough cooking can eliminate the presence of bacteria in food. Prompt refrigeration can prevent bacteria from contaminating leftovers and washing hands before and after handling raw meat products can halt the spread of bacteria to other foods. (Additional safe food handling tips can be found on the website of the Canadian Partnership for Consumer Food Safety Education www.canfightbac.org )
Is there anything that people can do when taking human medications to decrease the risk of developing antimicrobial resistance?
- Yes. It is important to finish taking all medications prescribed by physicians. Many times, people stop taking medication when they start to feel well, thinking that it is no longer needed. That is a mistake. Failure to complete all medications prescribed can allow more stubborn bacteria to survive, grow stronger and possibly develop resistance. Do not use unfinished prescriptions to "treat" future illnesses. Not all antimicrobials treat all diseases.
The following issues of Inforum also deal with antimicrobial resistance:
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