Dr. Zhanel - Protein Synthesis Inhibitors

Question 1

Prokaryotic cells have ___ ribosomes

Answer 1

70S (made up of 50S and 30S subunits)

Question 2

Eukaryotic cells have ___ ribosomes

Answer 2

80S (made up of 60S and 40S subunits)

Question 3

Protein synthesis inhibitors are all _______ except aminoglycosides

Answer 3

bacteriostatic

Question 4

The difference in ribosomal structure accounts for the ____ _____ of antibiotics that affect protein synthesis

Answer 4

selective toxicity

Question 5

However mitochondrial (important eukaryotic organelles) ribosomes are 70S and similar to that of bacteria. Thus _____ _____ on host cells may occur.

Answer 5

adverse effects

Question 6

Which antibiotics act on 30S site of bacterial ribosome?

Answer 6

aminoglycosides

tetracyclines

Question 7

Which antibiotics act on 50S site of bacterial ribosome?

Answer 7

chloramphenicol
clindamycin
macrolides
ketolides
oxazolidinones

Question 8

Describe Gentamycin (Protein synthesis inhibitor)

Answer 8

• bactericidal (because it is an amino glycoside)
• broad spectrum
• toxic (low therapeutic index)

Question 9

Which class of antibiotics do the following belong to:

• amikacin
• gentamicin
• netilmicin
• streptomycin
• tobramycin

Answer 9

aminoglycosides

Question 10

Which class of antibiotics do the following belong to:

• erythromycin
• clarithromycin
• azithromycin
• telithromycin

Answer 10

macrolides/ketolides

Question 11

Which class of antibiotics do the following belong to:

• tetracycline
• doxycycline
• minocycline
• tigecycline

Answer 11

Tetracyclines/glycylcyclines

Question 12

Which class of antibiotics do the following belong to:

-linezolid

Answer 12

oxazolidinones

Question 13

Describe macrolides (ex. erythromycin)

Answer 13

• bacteriostatic
• large therapeutic index )safe)
• used for RTI’s
• bind to 50S
• inhibits enzyme peptidyltransferase

Question 14

Clindamycin - possesses the same mechanism of action as _____

Answer 14

macrolides (binds to the 50S ribosome to inhibit protein synthesis)

Question 15

Describe tetracycline

Answer 15

• bacteriostatic
• generally safe
• broad spectrum
• used for acne
• may be used for RTI’s
• medium toxicity
• bind to 30S ribosome to A site
• prevents amino acid from coming in and binding to the A site
• inhibits protein synthesis
• inhibits growth

Question 16

Describe oxazolidinone (ex. linezolid)

Answer 16

• bacteriostatic
• medium therapeutic index
• narrow spectrum - covers staph and strep

Question 17

Describe chloramphenicol

Answer 17

• bacteriostatic
• safe
• medium toxicity
• binds to 50S
• prevents translocation

Question 18

MOA for streptomycin

Answer 18

• binds to 30S
• binds to mRNA
• disort message - cause lysis
• bactericidal

Question 19

Definitely see slide 7

Answer 19

okay man

Question 20

Mechanisms of Antimicrobial Resistance

_________: plasmid and chromosomal encoded inactivating enzymes (ex. phosphorus, acetyl, and adenylyl transferases) which modify the antibiotic, such that it no longer binds to ribosomal sites (ribosomal mutations)

Answer 20

Aminoglycosides

Question 21

Mechanisms of Antimicrobial Resistance

__________: plasmid mediated mono or di-methylation of adenine #2058 of the 23S rRNA (ermB gene confers cross-resistance to macrolides, clindamycin and streptogramins which results in reduced affinity between antibiotic and the ribosome) (efflux)

Answer 21

Macrolides/Ketolides

Question 22

Mechanisms of Antimicrobial Resistance

________: efflux across the cytoplasmic membrane. Alternation in ribosomal binding sites

Answer 22

Tetracyclines

Question 23

Mechanisms of Antimicrobial Resistance

________: plasmid or chromosomally encoded enzyme chloramphenicol acetyltransferase (CAT) modifies the antibiotic

Answer 23

Chloramphenicol

Question 24

Mechanisms of Antimicrobial Resistance

________: linezolid resistance is rare but mutations in 23S rRNA (a 50S ribosomal subunit)

Answer 24

Oxazolidinones