Lecture 4: Drug/Antimicrobial Use in Food-Producing animals Flashcards
What drugs are used in animals?
Hormones
Antimicrobials
Anti-inflammatories
Analgesics (reduce pain)
Anthelmintics (drug used to treat parasites)
Vaccines
Fluid/electrolytes
What classes of drugs for veterinary use exist and how does regulation occur?
3 classes of drugs for vet use:
1. Over-the-counter (OTC)
2. Prescription (Rx)
3. Medicated feed which also now need to be prescribed
Regulation occurs at different levels:
Provincial: Practice of Vet Medicine Regulation of OTC drugs
National: Vet Drugs Directorate Health Canada Licensing and Labelling
What is Extra-label drug use (ELDU)? Are all drugs allowed to use ELDU?
Any use of a drug not specifically listed on the label. EX changes in dose, route, frequency, indication, amount injected per site, withdrawal time.
No, some drugs and families of drugs are PROHIBITED for extra-label drug use
TRUE OR FALSE: Antimicrobial (AM) and Antibiotic are the same thing.
FALSE
Antimicrobial: kills or inhibits microorganisms (ex bacteria, viruses, protozoa)
Antibiotic: Kills or inhibits bacteria (subset of antimicrobial).
BOTH: Kills or inhibits microbial growth yet results in minimal or no damage to the host.
Why do we use AM in food animal production?
Health, welfare, production, food safety.
To prevent disease (prophylactically): during times of stress ie weaning after transport
To treat disease: outbreak in populations or illness in individual animals
To control disease: reduce disease spread after initial infection of some animals in herd/flock
To promote growth: Removal as of Dec 2018 of production enhancement or growth promotion claims.
What is the Antimicrobial Classification System?
4 categories of drugs that consider importance based on human medicine. 1-3 are Medically Important Antimicrobials (MIA).
1 very high importance
2 high importance
3 medium importance
4 low importance (over the counter w/o prescription)
What is the rationale for the Antimicrobial Classification System?
How the classification is made on the antimicrobials that involve the following:
-Spectrum of activity of antimicrobials
-mode of action
-Mechanism of resistance
-Availability of alternative antimicrobial therapy (save for important uses if only 1 option and low availability)
-Potential for transfer of resistance
What is antimicrobial resistance (AMR)? What is an example?
Established when normally susceptible bacteria grow in the presence of medication given at levels intended to kill them or inhibit growth. (usually pathogens but our class use bacteria as ex)
Any population of bacteria have ones that carry genes of resistance. Given an antimicrobial that kills the non-resistant bacteria. But bacteria resistant to A and A, B still remain. Therefore they are left to grow and divide. After being exposed to another antimicrobial B the resistant to A die but now the A and B survive and divide. Killing all the non-resistant and leaving the resistant. Exposure to antimicrobials changes bacteria population structure and can result in populations of drug resistant bacteria. But does not induce resistance directly in individual bacteria
How do bacteria develop a resistance to antimicrobials?
- Develop genes for resistance through mutation (randomly, provide all different mutations some advantageous others disadvantageous)
- Picking-up genes for resistance from other bacteria (genes responsible for resistance may cluster together and move between bacteria as a unit) think about it as swapping genes
How are Antimicrobial resistance and food safety connected? Animals —> Humans
Creates a potential for movement of bacteria containing resistance genes/elements from animals into food.
Implies: Contamination of food at abattoir AND failure of cooking or hygiene with consumer
Potential exchange of resistance genes from animal commensal bacteria to human pathogenic bacteria in human gut (ex bacteria with AMR that got from previous section (animal commensal bacteria) is now giving resistant properties to your bacteria (human pathogenic bacteria).
NOT CONSUMPTION OF DRUG (antimicrobial) RESIDUES BY HUMANS
How are Antimicrobial resistance and food safety connected? Humans —> Humans
Antimicrobial use in people (person-person). Can be:
-Community-acquired
-Hospital-based (nosocomial)
What are some Human and Animal Health Consequences of the future in regards to antimicrobial resistance?
-Few (no) new antimicrobials are being developed (has been declining since 1980’s)
-Increased morbidity and mortality due to AMR (more people are sick longer and die to to AMR)
-Multi-drug resistance = can’t effectively treat diseases
-Alternative antimicrobials INCREASE toxicity, DECREASE efficacy, INCREASE cost
-Increasing public concern internationally
For preventing AMR: Prudent Use what is the 5-R Approach to Antimicrobial Stewardship?
*Responsibility: Use the right drug, on the high animal, against the right condition, at the right dose, at the right time (usually on the label)
*Reduce: Reduce antimicrobial use by establishing good management protocols to reduce disease risk (good production practice)
*Replace: Replace antimicrobial use with other medications when possible, or use vaccines to prevent disease (relates to label, ex AM for viruses won’t work)
*Review: Review medication usage periodically to identify areas for improvement
*Refinement: Refine use by selecting the most appropriate medication (using one targeted to the deal with the one your worried about)
How do you prevent AMR using the multi-pronged approach to disease prevention and control?
-Biosecurity
-Assessment and monitoring
-Diagnostics and vaccinations
-Nutrition
-Good stockmen-ship
-Facility improvements
How do you prevent AMR using surveillance & research?
CIPARS (Canadian Integrated Program for Antimicrobial Resistance Surveillance) nominal integrated surveillance program that:
-collects data about AM use in animals and plants
-collects data about AMR in humans and animals
-Brings all these different pieces of info together to better understand the ecology of AMR across Canada
