Antibiotics

Question 1

What are bacteriostatic drugs?

Answer 1

Slows growth - bacteria cant reproduce

Will start to grow again when drug is removed
Rely on working immune system to clear the rest of

Question 2

What are bactericidal drugs?

Answer 2

Kills bacteria

Question 3

What are the two different types of bacteriocidal drugs?

Answer 3

Time dependent drugs

Concentration dependent drugs

Question 4

What is does a time dependent drug mean?

Answer 4

Drug needs to stay at effective concentrations within the body for as long as possible
Peak conc doesnt matter

Question 5

What does concentration dependent drug mean?

Answer 5

Peak conc determines effectiveness of drug

Big dose better - quicker

Question 6

What are inhibitors of peptidoglycan cell wall synthesis?

Answer 6

Beta lactams - penicillins and cephalosporins

Question 7

What are beta lactams more effective against?

Answer 7

Gram positive bacteria

Question 8

What can cause beta lactam resistance?

Answer 8

Beta lactamase produced by bacteria to break down the drug

Question 9

What can be used to inhibit beta lactamases so reduce beta lactam resistance?

Answer 9

Clavulanic acid - given alongside beta lactams

Question 10

Which is the best beta lactam drug?

Answer 10

Amoxicillin

Question 11

How are penicillins distributed?

Answer 11

Widely - dont cross blood brain barrier

Question 12

How are beta lactams eliminated?

Answer 12

By the kidney

Question 13

What is the therapeutic ratio of beta lactams?

Answer 13

Wide - mammalian cells dont have a cell wall

Question 14

What adverse reactions are a risk from beta lactams?

Answer 14

Hypersensitivity reactions

GI superinfection - death of gut flora

Question 15

What antibiotics inhibit bacterial protein synthesis?

Answer 15

Aminoglycosides
Macrolides
Tetracyclines
Chloramphenicol

Question 16

What effect do aminoglycosides have on bacterial protein synthesis?

Answer 16

Cause misreading of translation - wrong tRNA binds

Question 17

What type of bacteria do aminoglycosides affect?

Answer 17

Mostly gram negative

More effective against aerobic bacteria - energy dependent to cross outer membrane

Question 18

Are aminoglycosides bacteriostatic or bacteriocidal?

Answer 18

Bacteriocidal - concentration dependent

Question 19

Are beta lactams bacteriostatic or bacteriocidal?

Answer 19

Bacteriocidal - time dependent

Question 20

What are the adverse reactions of aminoglycosides?

Answer 20

Nephrotoxicity - bind to proximal tubule cells

Ear damage

Question 21

How are aminoglycosides administered?

Answer 21

IV, SC injections

Question 22

How do macrolides prevent bacteril protein synthesis?

Answer 22

They bind to the P side in the ribosome to prevent translocation of the mRNA

Question 23

What is an example of a macrolide antibiotic?

Answer 23

Erythromycin

Question 24

What type of bacteria do macrolides affect?

Answer 24

Gram positive bacteria (not at all gram negative)

Question 25

Are macrolides bacteriostatic or bacteriocidal?

Answer 25

Bacteriostatic | Erythromycin bacteriocidal at high doses

Question 26

How do tetracyclines affect bacterial protein synthesis?

Answer 26

Bind to the A site on the ribosome - prevents tRNA binding

Question 27

What bacteria does tetracyclines affect?

Answer 27

Wide spectrum - everything | But due to this they are prone to resistance

Question 28

What impairs tetracycline absorption?

Answer 28

Calcium/milk products

Question 29

What is tetracycline distribution?

Answer 29

Wide - including CNS

Question 30

Why do tetracyclines not affect mammalian cells?

Answer 30

Dont have the carrier protein to cross cell membrane

Question 31

What is the main resistance mechanism of bacteria against tetracyclines?

Answer 31

Efflux pump

Question 32

What adverse reactions can you get to tetracyclines?

Answer 32

GI disturbances Dont give orally to ruminants Chelate calcium - affects enamel on teeth

Question 33

How do chloramphenicols prevent bacterial protein synthesis?

Answer 33

Inhibit peptide bond formation

Question 34

Are chloramphenicols bacteriostatic or bacteriocidal?

Answer 34

Bacteriostatic

Question 35

What adverse reactions can chloramphenicols cause?

Answer 35

Anaemia by suppression of bone marrow

Question 36

How are chloramphenicols administered?

Answer 36

Orally

Question 37

What type of bacteria do chloramphenicols affect?

Answer 37

Best against obligate anaerobes but also affects all other types

Question 38

What do antibiotic drugs affecting bacterial DNA synthesis target?

Answer 38

Folate synthesis

Question 39

What antibiotics affect folate synthesis?

Answer 39

Sulphonamides | Trimethoprim

Question 40

How do sulphonamides affect bacterial DNA synthesis?

Answer 40

Competitive inhibitor of DHPS enzyme which is used to produce folate

Question 41

What bacteria types do sulphonamides affect?

Answer 41

Wide spectrum - both gram positive and negative

Question 42

Are sulphonamides bacteriostatic or bacteriosidal?

Answer 42

Bacteriostatic

Question 43

What adverse reactions can sulphonamides cause?

Answer 43

Hypersensitivity reactions

Question 44

How does trimethoprim affect bacterial DNA synthesis?

Answer 44

Inhibits DHFR enzyme

Question 45

What can trimethoprim be combined with and why?

Answer 45

Sulphonamides Combination is bacteriocidal Also effecting against protozoal infections

Question 46

What is a problem with trimethoprim and sulphonamides combination?

Answer 46

Resistance is a big problem

Question 47

How do fluoroquinolones affect bacteria?

Answer 47

They interfere with the packaging of the chromosome within the bacteria - interfere with DNA gyrase

Question 48

What bacteria do fluoroquinolones affect?

Answer 48

Wide spectrum - except obligate anaerobes

Question 49

Are fluoroquinolones bacteriostatic or bactericidal?

Answer 49

Bactericidal

Question 50

What adverse reactions do fluoroquinolones cause?

Answer 50

Rare - very popular due to this so shouldnt use as first line treatment (resistance)

Question 51

How does metronidazole affect bacteria?

Answer 51

Causes DNA fragmentaton

Question 52

What bacteria does metronidazole affect?

Answer 52

Obligate anaerobes only

Question 53

How is metronidazole excreted?

Answer 53

Renal and hepatic excretion

Question 54

What adverse reactions does metronidazole cause?

Answer 54

Rare, usually mild | Cats may salivate a lot