Equine Antimicrobials

Question 1

How do Beta lactam antibiotics work?

Answer 1

Interfere w/cell wall -> lysis

Question 2

Which class of antimicrobial should be used FIRST LINE in streptococcal infections of the horse?

Answer 2

Beta Lactams

Question 3

Which gram staining bacteria are beta lactams effective against?

Answer 3

Gram +

Question 4

Which antimicrobial class works synergistically with beta lactams?

Answer 4

Aminoglycosides

Question 5

Where do beta lactams not work well?

Answer 5

Abscesses

Question 6

Are beta lactams effective against aerobes or anaerobes?

Answer 6

Anaerobes

Question 7

What is the mechanism of action of cephalosporins?

Answer 7

Interfere w/cell wall -> lysis BUT more resistant to bacterial defences than Beta Lactams

Question 8

How do aminoglycosides work?

Answer 8

30s Ribosomal Subunit -> DNA misread

Question 9

What are the 2 main indictions for aminoglycoside use?

Answer 9

Gram -ve

Pseudomonas

Question 10

What is the major SE of aminoglycosides?

Answer 10

Nephrotoxicity

Question 11

What is the MOA of chloramphenicol?

Answer 11

50s Ribosomal Subunit - inhibit protein synthesis

Question 12

What must be noted when using chloramphenicol in horses and other large animals?

Answer 12

PROHIBITED in food production animals

Question 13

With which antimicrobials can chloramphenicol NOT be prescribed?

Answer 13

Penicillin
Aminoglycosides
Fluoroquinolones
Macrolides

Question 14

What is the MOA of potentiated sulphonamides?

Answer 14

Inhibit DNA synthesis via the folic acid pathway

Question 15

Where are potentiated sulphonamides ineffective?

Answer 15

Pus/necrotic tissue

Anaerobes

Question 16

When can potentiated sulphonamides cause fatal arrhythmias?

Answer 16

when given with Detomidine!!

Question 17

What is the MOA of tetracyclines?

Answer 17

30s ribosomal subunit binding - inhibit protein synthesis

Question 18

Are tetracyclines static or cidal?

Answer 18

Static

Question 19

Are aminoglycosides static or cidal?

Answer 19

Cidal

Question 20

Are fluoroquinolones static or cidal?

Answer 20

cidal

Question 21

Is chloramphenicol static or cidal?

Answer 21

Static

Question 22

Are macrolides static or cidal?

Answer 22

static

Question 23

Apart from infections, when are tetracyclines used?

Answer 23

Chelate Ca at myotendinous jct in foals w/contracted tendons

Inhibit MMPs in keratomalacia

Question 24

What is the spectrum of action for tetracyclines?

Answer 24

Broad!!

Question 25

What is the MOA of fluoroquinolones?

Answer 25

inhibit DNA gyrase - bactericidal

Question 26

What is the spectrum of action for fluoroquinolones?

Answer 26

BROAD

esp good against gram neg

Question 27

What are fluoroquinolones ineffective against?

Answer 27

Anaerobes

Question 28

What may be a side effect of administering fluoroquinolones in foals?

Answer 28

Cartilage esions

Question 29

On which antimicrobials do fluoroquinolones have an antagonistic effect?

Answer 29

Chloramphenicol

Rifampin

Question 30

What is the MOA of macrolides?

Answer 30

50s ribosomal subunit - inhibit protein synthesis.

Question 31

What are macrolides used to treat? (EQ)

Answer 31

R. Equi in foals

Question 32

Why aren’t macrolides used in adult horses?

Answer 32

Colitis risk

Question 33

What is the MOA of rifampin?

Answer 33

Inhibit bacterial RNA polymerase

Question 34

Apart from viruses and fungi, which 3 pathogens is rifampin effective against in horses?

Answer 34

Staph
R. Equi
Mycobacteria

Question 35

What is the MOA of metronidazole?

Answer 35

Broken down into free radicals –> DNA damage