AB - Protein synthesis inhibitors

Question 1

What class of antibiotics are aminoglycosides?

Answer 1

Protein synthesis inhibitors

Question 2

True or False: Aminoglycosides have a post-antibiotic effect

Answer 2

True

They are unique because they are bactericidal protein synthesis inhibitors.

Question 3

What are the two mechanisms of action of aminoglycosides?

Answer 3

1. Prematurely inhibit protein synthesis by adding incorrect amino acids (irreversible)
2. Disrupt bacterial biofilms (especially Gram-negatives)

Question 4

Are aminoglycosides bacteriostatic or bactericidal?

Answer 4

Bactericidal

Unlike other protein synthesis inhibitors because it binds irreversibly.

Question 5

Aminoglycosides are ___________ dependent

Answer 5

Concentration

Question 6

Why do aminoglycosides have a strong post-antibiotic effect?

Answer 6

Because aminoglycosides bind irreversibly to their target, allowing a long dosing interval.

Question 7

Aminoglycosides are a category _______ drug

Answer 7

2

Question 8

Aminoglycosides are not effective against __________

Answer 8

Anaerobes

Question 9

Aminoglycosides are synergistic with which other antibiotic?

Answer 9

Cell-wall disruptors such as the beta-lactams

Beta-lactams shouldn’t be given with bacteriostatic drugs - aminoglycosides are bactericidal.

Question 10

True or False: Aminoglycosides are effective for treating UTIs

Answer 10

False

Their activity is pH dependent and they are inactivated at low pH (ex. in urine).

Question 11

Which factors inactivate aminoglycosides?

Answer 11

• Inactivated if combined in syringe with other drugs (including, importantly, penicillins)
• Inactivated at low pH (urine)
• necrotic/purulent material

Question 12

Why can’t aminoglycosides be given to food animals?

Answer 12

They accumulate in the renal cortex and have violative residues in kidney that can last more than a year after administration!

Question 13

Why can’t aminoglycosides be administered orally?

Answer 13

They are not absorbed from the GI tract so they must be injected or administered topically.

Question 14

What are two main adverse effects of aminoglycosides?

Answer 14

• Nephrotoxic
• Ototoxic

Question 15

What are the two main aminoglycosides?

Answer 15

Gentamicin and Amikacin

Question 16

Aminoglycosides are most effective against what type of bacteria?

Answer 16

Aerobic Gram-negatives and Staphylococcus

Question 17

What conditions are aminoglycosides commonly used to treat?

Answer 17

Equine joint infections and eye and ear infections

Question 18

What are some differences between gentamicin and amikacin?

Answer 18

Amikacin is more effective against Staphylococcus spp. (Amikacin is broader spectrum).

Question 19

What class of antibiotics are macrolides and lincosamides?

Answer 19

Protein synthesis inhibitors

Question 20

True or False: Macrolides and lincosamides can be used together

Answer 20

False

They reduce each other’s efficacy by physically overlapping at their binding sites.

Question 21

Why are macrolides and lincosamides different drug classes when they are so similar?

Answer 21

Although they have the same mechanism of action and are effective against similar bacteria, their structure is very different.

Question 22

Are macrolides and lincosamides bacteriostatic or bactericidal?

Answer 22

Bacteriostatic

Although can be bactericidal depending on the bacteria they are targeting.

Question 23

Macrolides and lincosamides are ___________ dependent

Answer 23

Time

Question 24

When are macrolides and lincosamides often used?

Answer 24

When there is resistance to penicillin.

Question 25

What are macrolides and lincosamides most effective against?

Answer 25

Gram-positive organisms

Question 26

Why don't macrolides and lincosamides cause adverse effects in animals?

Answer 26

They do not bind mammalian ribosomes.

Question 27

Which macrolides are commonly used in production animals?

Answer 27

- Erythromycin - Tulathromycin - Tilmicosin

Question 28

Which macrolides are used in foals and small animals?

Answer 28

- Azithromycin - Clarithromycin

Question 29

Which lincosamide is commonly used in swine and poultry?

Answer 29

Lincomycin

Question 30

Which lincosamide is commonly used in small animals?

Answer 30

Clindamycin

Question 31

True or False: Lincosamides can be used in all production animals

Answer 31

False ## Footnote They are contraindicated in hindgut fermenters and ruminants.

Question 32

What are tulathromycin and tilmicosin commonly used to treat?

Answer 32

Gram-negative respiratory pathogens ## Footnote Tilmicosin is used for BRDC.

Question 33

Why are macrolides commonly used to treat respiratory infections?

Answer 33

Because they penetrate well into the lung tissue.

Question 34

What conditions are azithromycin used to treat in foals?

Answer 34

Rhodococcus equi infections

Question 35

What are the adverse effects of tilmicosin?

Answer 35

Tilmicosin is cardiotoxic!! ## Footnote Horses, goats, swine, companion animals, and humans may DIE after administration!

Question 36

Which drugs are contraindicated in hindgut fermenters due to the adverse effects on their GI flora?

Answer 36

Lincosamides (lincomycin and clindamycin)

Question 37

Clindamycin has better activity against ____________

Answer 37

Anaerobes

Question 38

What is clindamycin commonly used to treat in small animals?

Answer 38

Pyoderma and dental infections

Question 39

What class of antibiotic are phenicols?

Answer 39

Protein synthesis inhibitors

Question 40

What are the two classes of phenols?

Answer 40

Chloramphenicol and florfenicol

Question 41

What is unique about the mechanism of action of chloramphenicol?

Answer 41

It inhibits mammalian as well as bacterial protein synthesis (particularly mitochondrial protein synthesis).

Question 42

Are phenicols bacteriostatic or bactericidal?

Answer 42

Bacteriostatic

Question 43

Phenicols are ________ dependent

Answer 43

Time

Question 44

Phenols are considered a category __________ drug

Answer 44

3

Question 45

Which tissues are phenicols effective at penetrating?

Answer 45

All tissues (it even crosses placenta and enters the CNS).

Question 46

What are the adverse effects of chloramphenicol?

Answer 46

It can cause fatal aplastic anemia in humans (wear gloves) and bone marrow suppression in cats.

Question 47

What is unique about the administration method of chloramphenicol?

Answer 47

It is one of the few drugs that can be administered orally to horses.

Question 48

Which bacteria are chloramphenicol most effective against?

Answer 48

It is very broad spectrum so it's basically effective against everything.

Question 49

What is the difference between florfenicol and chloramphenicol?

Answer 49

Florfenicol is a safer derivative of chloramphenicol (modified to remove aplastic anemia risk) and is narrower spectrum (mostly effective against Gram-negatives).

Question 50

What is florfenicol commonly used to treat in production animals?

Answer 50

Respiratory infections (not used in horses though).

Question 51

What class of antibiotics are fluoroquinolones?

Answer 51

DNA and RNA disruptors

Question 52

Are fluoroquinolones bacteriostatic or bactericidal?

Answer 52

Bactericidal

Question 53

Fluoroquinolones are ___________ dependent

Answer 53

Concentration

Question 54

Which class of antibiotics are the only ones with good activity against Pseudomonas?

Answer 54

Fluoroquinolones

Question 55

Which tissues do fluoroquinolones penetrate well?

Answer 55

Bone and prostate

Question 56

Fluoroquinolones are a category ___________ drug

Answer 56

1

Question 57

Where do fluoroquinolones accumulate?

Answer 57

Intracellularly

Question 58

What is the most common fluoroquinolone used in veterinary medicine?

Answer 58

Enrofloxacin

Question 59

What conditions is enrofloxacin used to treat in small animals?

Answer 59

Bacterial cystitis, pyelonephritis, prostatitis, and enteritis

Question 60

True or False: Enrofloxacin should not be used extra-label in production animals

Answer 60

True