Antimicrobials - Muller

Question 1

What is an antimicrobial?

Answer 1

Any substance of natural, semi-synthetic, or synthetic origin that kills or inhibits growth of microorganisms but causes little damage to the host

1. Antibiotics / antibacterials
2. Antivirals
3. Antifungals
4. Antiparasitics

Question 2

What defines an antibiotic?

Answer 2

Has capacity in dilute solution to selectively inhibit the growth or kill other organisms

1. Old natural molecules
2. Produced by soil-dwelling organisms

Question 3

Give an example of an antibiotic thats MOA is by inhibition of cell wall synthesis

Answer 3

Penicillin

** bacteriocidal action

Question 4

Give an example of an antibiotic thats MOA is inhibition of protein synthesis

Answer 4

Tetracyclines

**bacteriostatic action

Question 5

Give an example of an antibiotic thats MOA is by inhibition of nucleic acid synthesis

Answer 5

Quinolones, rifampin

Question 6

List 4 B-lactams

Answer 6

1. Penicillins
2. Cephalosporins
3. Carbapenems
4. Monobactams

Question 7

Give an example of an antibiotic with a hydrocarbon ring

Answer 7

Tetracyclines

Question 8

When is it preferred to use a bacteriocidal antibiotic?

Answer 8

For more serious or life threatening infections

Or in immunocompromised

Question 9

Why wouldnt you want to use a bacteriostatic antibiotic in an immunosuppressed animal?

Answer 9

Bc bacteriostatic antibiotic inhibits growth but requires immune system to further clear infection

**immunosuppressed wont be able to do this

Question 10

What are examples of bacteriostatic antibiotics?

Answer 10

Tetracyclines, Macrolides, Sulfonamides

Question 11

What are examples of bactericidal antibiotics?

Answer 11

Beta lactams, Fluoroquinolones, Polymyxin

Question 12

Tetracyclines vs Penicillins: which one is broad spectrum?

Answer 12

Tetracycline - broad spectrum

Penicillin - narrow spectrum

Question 13

What 2 methods are used for antimicrobial susceptibility testing in vitro?

Answer 13

1. Diffusion method (Qualitative or Quantitative)
   Ex: Kirby Bauer test
2. Dilution method (Quantitative)
   Ex: Broth dilution test

** E-test combines both

Question 14

What is MIC?

Answer 14

Minimum Inhibitory Concentration

• lowest conc. of an antimicrobial that will inhibit growth

Question 15

What is MBC?

Answer 15

Minimal bactericidal concentration

• lowest conc. of an antimicrobial that will KILL a bacterium

Question 16

What susceptibility test uses both principles from diffusion and dilution?

Answer 16

Concentration gradient diffusion test (E TEST)

** uses a strip on agar plate to determine MIC values

Question 17

What does an intermediate sensitivity mean?

Answer 17

Infecting organism is inhibited with MAX dosage of antibiotic

Question 18

What are the 4 difference MOA for bacteria?

Answer 18

1. Inhibits cell wall synthesis
2. Damages cell membrane function
3. Inhibits nucleic acid synthesis
4. Inhibits protein synthesis
   ** only 1 that is bacteriostatic

** all others are bactericidal

Question 19

what is a kirby bauer test?

Answer 19

DIFFUSION TECHNIQUE

measures the diameter of the zone of inhibition to tell if an antibiotic is susceptible, intermediate, or resistant

Question 20

What is the broth dilution test?

Answer 20

Measures minimum inhibitory conc. (MIC)

** the lowest conc. of an antimicrobial that will INHIBIT visible growth

** the first tube with no growth is the MIC