Drug Therapy Flashcards
Define antimicrobial.
-any substance of natural, semi-synthetic or synthetic origin that kills/inhibits growth of microorganisms
-little damage to host
Define antibiotic.
-produced by microorganisms (soil dwelling)
-capacity in dilute solution to selectively inhibit the growth/kill other microorganisms
-communication between microorganisms
-inhibition of potential competitive microorganisms
Describe prophylactic use.
-treatment of healthy herd to prevent infection
Describe metaphylactic use.
-treatment of diseased herd to cure infection in some & prevent infection in others
Describe growth promotion in the US.
-treatment of healthy animals with low (sub-therapeutic) concentrations in feed
-improves growth rate, efficiency of feed utilization & improve reproduction
Describe growth promotion in EU.
-EU banned use of antibiotic growth promoters (AGP)
-elimination of AGP = rise in prescribed vet antimicrobial for preventative use
-to address preventative use of antibiotics, regulators introduced a “yellow card” system
Describe growth promotion in the FDA.
-promote use of imp antimicrobial drugs in food animals
-document to phase out use of antimicrobial for production purposes
enhance growth/improve feed efficiency
Describe what the FDA does to change growth promotion.
-remove use of antimicrobial drugs for production purposes
-when appropriate use treatment, control, or prevention uses
-change marketing status from OTC to veterinary feed directive for drugs administered through feed or to prescription status for drugs administered through water
What are antibiotic alternatives?
- Probiotics
- Prebiotics
- Organic acids
- Phytogenics (essential oils, oleoresins)
- Enzymes
- Hyperimmune IgY
- Antimicrobial peptides
- Others (bacteriophages, clay)
Describe classification of antibacterial agents.
-chemical structure
-origin
-spectrum
-mode of action
-anti-microbial effect
Describe the chemical structure of antibiotics.
- Macrolide (ex. Erythromycin)
- Aminoglycoside (ex. Gentamicin)
- Tetracycline (ex. HCL)
- Beta Lactams
- Sulfonamides & dipyrimidine
Describe the origin of antibiotics.
-natural: produced by fungi & bacteria “true”
-semi-synthetic: chemically altered natural compounds
-synthetic: chemically designed by humans
Describe broad spectrum antimicrobials.
-antimicrobial against gram + & gram - microorganisms
(EX: tetracycline, chloramphenicol, 3rd gen fluoroquinolone, cephalosporin)
Describe narrow-spectrum antimicrobials.
-antimicrobials with limited activity against particular species of microorganisms
(EX. Penicillin, polymyxin)
Describe the antimicrobial spectrum.
-gram pos
-gram neg
-aerobe
-anaerobe
-intracellular
-mycoplasma
-Protozoa
-fungi
Describe cell wall synthesis inhibitors.
(EX: beta-lactam antibiotics like penn, amp, cephalosporin, carbapenem, monobactam)
-promote autolysin activity -> cell lysis
-inhibit peptidoglycan synthesis by binding to PBP’s involved in synthesis
Describe protein synthesis inhibitors.
(EX: aminoglycosides, macrolides, chloramphenicol)
-inhibit 50s or 30s ribosomal chromosome
Describe bactericidal drugs.
-kill microorganisms & reduce total # of viable bacteria
Describe bacteriostatic drugs.
-inhibit growth & multiplication of bacteria
-allows host immune system to complete pathogen elimination
-drugs can be both bactericidal or bacteriostatic depending on:
>drug conc
>presence of other drugs
>bacterial species
Describe antiviral drugs.
-interfere with ability of virus to:
>infiltrate target cell
>target diff stages of replication & synthesis of components
-synthesize antibodies or administer natural antiserum
Describe immune system stimulation.
-interferons, class of proteins that has antiviral effects & modulate functions of immune system
Describe anthelminthics.
Ideally:
-orally effective
-effective in single dose
-inexpensive
-wide safety margin with high toxicity to worms but not host
-no/low tissue residue
[ex: benzimidazoles (mebendazole, albendazole), ivermectin, praziquantel]
Describe vermicide.
Anthelmintics that kill infesting helminths.
Describe vermifuges.
Anthelmintics that expel infesting helminths.
What are the factors affecting drug choice?
- Infection: nature, location, severity, susceptibility of causal pathogen
- Antimicrobial action & effect: variables influencing clinical response
- Experience: of a vet
- Cost: of treatment
- Compliance
- Toxicity: risk of adverse effects, withdrawal period
- Host: species, health, status, age, “value”
- Pharmacokinetic drug: formulation, preparations, route of administration, dosage
Describe the pros & cons of single or combination drug therapy.
Disadvantage of single drugs:
-high dose
-toxicity
-altered cell metabolism
-drug resistance
Advantages of combinatorial drugs:
-require lower dose
-synergistic response
-decrease probability of resistance evolution
-broad spectrum of action
-multiple targets
Describe antimicrobial selection.
- Mixed population of bacteria = one individual may have a gene providing resistance to an antibiotic
- When the antibiotic is administered = all of the susceptible pathogens are killed
- Resistant individuals = freed from resource constraints & multiplies
- After antibiotic course = susceptible individuals return = resistance gene is spread
Describe co-resistance.
Co-existence of multiple genes or mutations encoding resistance to diff drugs within same strain or genetic element.
Describe cross-resistance.
Resistance against one compound = automatically resistant against another compound
>same chemical group
>EX: macrolides, phenicols, lincomycins
Describe co-selection.
Selection of multiple resistance genes when one gene is selected.
-EX: Res A gives resistance to antibiotic A
Describe the hotspots for antimicrobial selection.
-antibiotic pollution coupled w contamination by heavy metals & other chemicals
-promote development of resistance mechanisms (co-selection)
What are the 3 types of AMR in vet med?
