Antimicrobials

Question 1

Describe antimicrobials VS antibiotics.

Answer 1

1. Antimicrobial
   -natural, semi synthetic or synthetic origin that kills or inhibits growth of microorganisms but causes little/no damage to host
2. Antibiotic
   -chem substance made by microorganism that has capacity in dilute solution to selectively inhibit the growth or kill other microorganisms
   >made by soil dwelling organisms
   >old natural molecule
   >communicate between diff microorganisms
   >inhibit potential competitive microorganisms

Question 2

Describe the ideal qualities of an antibiotic.

Answer 2

1. Kill/inhibit growth of microorganism
2. Little/no damage to host
3. No allergic reaction to host
4. Remain in specific bod tissue in host long enough to be effective
5. Stable when stored in solid or liquid form
6. Target pathogen before they mutate or become resistant to it

Question 3

Describe antibiotic development pipeline.

Answer 3

Question 4

Describe the chemical structure of antibacterial agents.

Answer 4

1. B Lactams
   -beta Lactam ring
2. Aminoglycosides
   -amino sugar substructure
3. Tetracyclines
   -4 adjacent cyclic hydrocarbon ring
4. Macrolides
   -14, 15, or 15-membered macrolide ring
5. Sulfonamide
   -sulfonamide group
6. (Fluoro)Quinolones
   -fused aromatic rings w carboxylic acid group

Question 5

Describe the mode of action.

Answer 5

Question 6

Describe the antimicrobial effect.

Answer 6

1. Bactericidal = death & disruption of bacterial cell
   -reduce # of viable cells
   -preferred for serious infections or immunocompromised
   -act on cell wall syn, cell membrane, DNA syn
2. Bacteriostatic = inhibit growth & multiplication of bacteria
   -require IS to further clear infection
   -inhibit protein syn & pathways
   *some drugs can be either depending on:
   ~drug conc, presence of other drugs, bacterial species

Question 7

Describe how we can reach the desired antimicrobial effect in the body of host at infection site.

Answer 7

-ADME principle of drug delivery
-solubility of drug at target site
>chemical & physiological processing in the bod
>chem properties of drug
-host factors
-combination therapy of drugs
>inc efficacy & spectrum
>synergic effect
*bacteriostatic drugs need growth to stop & bactericidal drugs need growth to act = antagonism

Question 8

Describe pharmacokinetic/pharmacodynamic (PK-D) model.

Question 9

Describe spectrum of activity.

Answer 9

Question 10

Describe antibiotic selection.

Answer 10

AMR

Question 11

Describe rational antimicrobial use.

Answer 11

-actions that prevent/min development of resistance in strain causing infection in patient commensal microbiota w/o impacting clinical efficacy
1. (Systemic) antimicrobial
-reduce overall antimicrobial consumption
2. Choice of drug
-prudent use of 2nd line, imp antimicrobials
3. Culture
-improve use of diagnostic testing
4. Which drug dosage
-optimize dose regime

Question 12

Describe antimicrobial stewardship.

Answer 12

-coordinated interventions/program to improve & measure use of antimicrobials by promoting selection of optimal antimicrobial drug regimen, dose, duration of therapy, route of administration

Question 13

Describe the traffic light antimicrobial principle.

Answer 13

Ranks antimicrobials according to OIE & WHO:
1. Red
-antimicrobial in vet med of high imp
-most appropriate
-culture & sensitivity testing
2. Yellow
-antimicrobial of diff class or special features
-human therapy
-not used where efficacy is in doubt
3. Green
-recommended against known susceptible organisms
-not used where efficacy is in doubt
-known actions, 1st choice

Question 14

Describe the use of antimicrobials of skin infections & otitis in dogs.

Answer 14

Antimicrobial?
-surface pyoderma = NO
-superficial pyoderma = only if topical treatment fails or not possible
-deep pyoderma = YES
-otitis = if evidence of ruptured tympanic membrane or otitis media (not tumor, or hair, etc)

Question 15

Describe cultures for skin infections & otitis in dogs.

Answer 15

Recommended:
-no response to therapy
-prev antibiotic treatment
-relapse or reinfection
-immunocompromised
-life threatening infection
-risk of MDR
-high AMR
-long treatment

Question 16

Describe the limitations of cultures.

Answer 16

-interfere w commensal bacteria
-invasive
-high risk of contamination
-unculturable pathogen
-mixed cultured in otitis, wound infections
>target all strains cultured -> unnecessary use of broad spec antimicrobial
>target primary pathogen (most reasonable)