Fluoroquinolones

Question 1

What is the mechanism of action of FQs?

Answer 1

Inhibit DNA gyrase and topoisomerase

Question 2

Are FQ bacteriostatic or bactericidal?

Answer 2

Bactericidal (due to inhibition of 2 enzymes)

Question 3

What is the spectrum of the FQs?

Answer 3

Gram (+) and gram (-), but NO ANAEROBES

Question 4

Nalidixic acid is the non-fluorinated precursor that only kills some gram (-). What is added to extend the spectrum of FQs to gram (+)s?

Answer 4

Fluorine

Question 5

What is the most common method of resistance to FQs?

Answer 5

Point mutation in DNA gyrase genes

Question 6

Which bug has the fastest development of resistance against the FQs?

Answer 6

Campylobacter

Question 7

Are FQs time, concentration, or AUC/MIC-dependent?

Answer 7

AUC/MIC-dependent

Question 8

What is the MPC?

Answer 8

Mutation prevention concentration

Question 9

What is the MPC for gram (+)?

Answer 9

x5

Question 10

What is the MPC for gram (-)?

Answer 10

x10

Question 11

In what 3 tissues do the FQs concentrate?

Answer 11

1. WBCs
2. Prostate
3. Brain

Question 12

Are FQs water soluble or lipid soluble?

Answer 12

Lipid soluble (high Vd)

Question 13

True or False: FQs are not absorbed well orally.

Answer 13

FALSE

Question 14

True or False: FQs are excreted mostly unchanged in the urine.

Answer 14

TRUE

Question 15

What toxicities are associated with the use of FQs?

Answer 15

1. Chondrotoxicity in neonates/juveniles
2. Retinopathies in cats
3. Exacerbates seizures in epileptic dogs
4. Herxhimer’s reaction
5. Inhibit p450 enzymes

Question 16

In which animals is the use of FQs banned?

Answer 16

1. Poultry

2. Food animals

Question 17

Which FQ is non-retinotoxic and used in the cat?

Answer 17

Pradofloxacin

Question 18

What is the MOA of novobiocin?

Answer 18

Prevents ATP from binding DNA gyrase

Question 19

Is novobiocin bacteriostatic or bactericidal?

Answer 19

Bacteriostatic

Question 20

Which bacterium is included in the limited spectrum of novobiocin?

Answer 20

Staph aureus

Question 21

What is the MOA of rifampin?

Answer 21

Inhibits RNA polymerase

Question 22

What is the spectrum of rifampin?

Answer 22

1. Mycobacteria

2. Gram (+)

Question 23

With which of the following does resistance develop rapidly, rifampin or novobiocin?

Answer 23

Rifampin

Question 24

What are the 2 side effects of IV rifampin in horses?

Answer 24

1. Sweating

2. Hemolysis

Question 25

What are the 3 toxicity issues associated with rifampin?

Answer 25

1. Orange discoloration of bodily fluids
2. Immune-mediated hepatitis
3. Inducer of microsomal enzymes

Question 26

What is the MOA of glycopeptides?

Answer 26

Cell wall synthesis inhibition

Question 27

Are glycopeptides bacteriostatic or bactericidal?

Answer 27

Bactericidal

Question 28

What is the spectrum of glycopeptides?

Answer 28

Gram (+)

Question 29

Name 3 glycopeptide drugs.

Answer 29

1. Vancomycin
2. Teicoplanin
3. Avoparcin

Question 30

Only use glycopeptides if absolutely necessary. What are 4 things to take into consideration when using this drug?

Answer 30

1. Vomiting likely
2. Nephrotoxic
3. Ionized in the gut (must be injected)
4. Tissue irritant (slow IV drip)

Question 31

Rifampin can be used against Rhodococcus equi in the horse. Combine this drug with what?

Answer 31

Clarithromycin