Macrolides and Fluroquinolones

Question 1

mechanisms of action for macrolides

Answer 1

inhibition of protein synthesis (bacteriostatic effect)

Question 2

main adverse effects for macrolides (2)

Answer 2

-tissue irritation: pain on injection (all macrolides), nausea and vomiting (oral erythromycin)
-potentially fatal colitis in hindgut fermenters

Question 3

first line macrolide

Answer 3

erythromycin

Question 4

second line macrolide

Answer 4

newer macrolides

Question 5

general spectrum for erythromycin

Answer 5

relatively broad

Question 6

PK features for macrolides (4)

Answer 6

-concentrate in lung
-enter cells
-most newer macrolides have long half lives
-erythromycin: inhibits P450 enzymes and stimulates motilin receptors

Question 7

general spectrum for newer macrolides

Answer 7

a mix but mainly gram -ve aerobes

Question 8

MOA for fluoroquinolones

Answer 8

damage DNA; inhibition of DNA gyrases and topoisomerases

bactericidal effect

Question 9

main adverse effects for fluoroquinolones (3)

Answer 9

-cartilage damage (immature animals)
-retinal damage/degeneration (enrofloxacin in cats)
-reduction in seizure threshold (can trigger seizures in epileptics)

Question 10

line of use for fluoroquinolones

Answer 10

second line (ongoing prudent use problems)

Question 11

general spectrum for for fluoroquinolones

Answer 11

similar to gentamicin

-many gram -ve, staph (gram +ve), atypical bacteria

Question 12

PK features for fluoroquinolones

Answer 12

-most have long half lives
-oral absorption 100%
-concentrate in lung

Question 13

what is the safest class of antibacterial drugs

Answer 13

macrolides

Question 14

what do the generic names end in if they are macrolides

Answer 14

osin or mycin

Question 15

is gentamicin a macrolide

Answer 15

no

Question 16

2 important uses of macrolides

Answer 16

1) intracellular pathogens
2) respiratory infections

Question 17

what is the name of a macrolide used for bacterial pnemonia in livestock

Answer 17

tilmicosin, effective against gram -ve aerobic lung pathogens

Question 18

when is tilmicosin fatal

Answer 18

IV injection in cattle
always fatal to swine

Question 19

what is tulathromycin approved for and in what species

Answer 19

in cattle and swine for bacterial pneumonia

Question 20

examples of macrolides

Answer 20

-tilmicosin
-tulathromycin
-gamithromycin

Question 21

what leads to resistance of macrolides

Answer 21

acquisition of plasmid-encoded efflux pump

Question 22

what is an adverse effect of tilmicosin specifically

Answer 22

can cause rapid cardiac fatalities in species other than cattle when administered parenterally

Question 23

Fluoroquinolones are best thought of as _________ drugs to be used for infections resistant to first-line
drugs

Answer 23

second line

Question 24

examples of fluroquinolines (5)

Answer 24

• Enrofloxacin (Baytril®)
• Orbifloxacin (Orbax®)
• Marbofloxacin (Zeniquin®)
• Difloxacin (Dicural®)
• Danofloxacin (A180®)

Question 25

what are all FQs ineffective against

Answer 25

obligate anaerobes

Question 26

what type of drug is banned in food producing animals

Answer 26

chloramphenicol

Question 27

what drugs should be avoided if possible due to human health? (3)

Answer 27

-FQs
-potentiated penicillin
-3rd generation cephalosporins