Macrolides (Lec 14)

Question 1

Macrolides are produced by?

3 Macrolide drugs?

Answer 1

actinomycete bacteria, Streptomyces

erythromycin
clarithromycin
azithromycin

Question 2

Macrolide antibiotic mechanism of action?

Answer 2

bind to 50S ribosomal subunits inhibiting protein synthesis

Question 3

Macrolide active against?

Bacteriostatic or cidal?

Answer 3

G+

(U) static

Question 4

Macrolide antibiotic spectrum?

Answer 4

similar to PCN G

Question 5

Resistance to Macrolides develops how?

Answer 5

efflux pumps

Question 6

Macrolide toxicity sxs? (4)

Answer 6

1) GI (erythro = most severe, clari = least)
2) allergy
3) hepatic
4) ototoxicity w/ IV erythro only

Question 7

Erythromycin or Clarithromycin can adversely interact w/ other drugs how?

Answer 7

Inhibits CYP3A4 needed to metabolize other drugs ->

causes higher serum concentrations of those drugs

Question 8

Erythromycin or Clarithromycin given w/ what drugs causes cardiac issues?

Answer 8

cisapride or pimozide

sparfloxacin or grepafloxacin

Question 9

Azithromycin DOC for what bacteria? (2)

Answer 9

legionella (+rifampin)

chlamydia trachomatis

Question 10

Clindamycin mechanism of action?

Answer 10

binds 50S subunit of rRNA -> inhibits protein synth

Question 11

Clindamycin active against?

Answer 11

G+ cocci

G+ and G- anaerobes

Question 12

Clindamycin side-effects? (2)

Answer 12

1) pseudomembranous colitis (c. diff)

2) rash

Question 13

Dalfopristin and Quinupristin method of action?

Administered?

Answer 13

(streptogramins)
bind 50S ribosomal subunits -> inhibit protein synth

Administered together by IV

Question 14

Dalfopristin/Quinupristin is -static or -cidal?

Answer 14

bactericidal

Question 15

Oxazolidinones Prototype drug?

Answer 15

Linezolid

Question 16

Linezolid active against?

Answer 16

G+ aerobes
VRE
MRSA

Question 17

Linezolid should be last choice of tx for?

Answer 17

Multi drug resistant (MDR) strains

Question 18

Clindamycin used to treat? (4)

Answer 18

1) toxic shock synd w/ vancomycin
2) osteomyelitis
3) toxoplasma encephalitis
4) MRSA

Question 19

Dalfopristin and Quinupristin used to treat? (3)

Answer 19

1) vanco-resistant enterococcus faecium
2) Skin infections: MSSA, MRSA
3) PCN-resistant s. pneumoniae, MDR-strep

Question 20

Oxazolidinones mechanism of action?

Answer 20

bind 23S rRNA of 50S subunit* ->
inhibits protein syth

(*unique binding site means no cross-resistance)

Question 21

Linezolid inhibits?

Answer 21

monoamine oxidase (MAO)

Question 22

Linezolid route of administration?

Answer 22

IV, oral

Question 23

Linezolid drug interactions? (4)

Answer 23

1) β-blocker
2) MAO inhib
3) anesthesia
4) antidepressants

Question 24

Erythromycin is prophylactic DOC for?

Answer 24

Pertussis