Dr. Zhanel - Protein Synthesis Inhibitors Flashcards
Prokaryotic cells have ___ ribosomes
70S (made up of 50S and 30S subunits)
Eukaryotic cells have ___ ribosomes
80S (made up of 60S and 40S subunits)
Protein synthesis inhibitors are all _______ except aminoglycosides
bacteriostatic
The difference in ribosomal structure accounts for the ____ _____ of antibiotics that affect protein synthesis
selective toxicity
However mitochondrial (important eukaryotic organelles) ribosomes are 70S and similar to that of bacteria. Thus _____ _____ on host cells may occur.
adverse effects
Which antibiotics act on 30S site of bacterial ribosome?
aminoglycosides
tetracyclines
Which antibiotics act on 50S site of bacterial ribosome?
chloramphenicol clindamycin macrolides ketolides oxazolidinones
Describe Gentamycin (Protein synthesis inhibitor)
- bactericidal (because it is an amino glycoside)
- broad spectrum
- toxic (low therapeutic index)
Which class of antibiotics do the following belong to:
- amikacin
- gentamicin
- netilmicin
- streptomycin
- tobramycin
aminoglycosides
Which class of antibiotics do the following belong to:
- erythromycin
- clarithromycin
- azithromycin
- telithromycin
macrolides/ketolides
Which class of antibiotics do the following belong to:
- tetracycline
- doxycycline
- minocycline
- tigecycline
Tetracyclines/glycylcyclines
Which class of antibiotics do the following belong to:
-linezolid
oxazolidinones
Describe macrolides (ex. erythromycin)
- bacteriostatic
- large therapeutic index )safe)
- used for RTI’s
- bind to 50S
- inhibits enzyme peptidyltransferase
Clindamycin - possesses the same mechanism of action as _____
macrolides (binds to the 50S ribosome to inhibit protein synthesis)
Describe tetracycline
- 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
Describe oxazolidinone (ex. linezolid)
- bacteriostatic
- medium therapeutic index
- narrow spectrum - covers staph and strep
Describe chloramphenicol
- bacteriostatic
- safe
- medium toxicity
- binds to 50S
- prevents translocation
MOA for streptomycin
- binds to 30S
- binds to mRNA
- disort message - cause lysis
- bactericidal
Definitely see slide 7
okay man
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)
Aminoglycosides
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)
Macrolides/Ketolides
Mechanisms of Antimicrobial Resistance
________: efflux across the cytoplasmic membrane. Alternation in ribosomal binding sites
Tetracyclines
Mechanisms of Antimicrobial Resistance
________: plasmid or chromosomally encoded enzyme chloramphenicol acetyltransferase (CAT) modifies the antibiotic
Chloramphenicol
Mechanisms of Antimicrobial Resistance
________: linezolid resistance is rare but mutations in 23S rRNA (a 50S ribosomal subunit)
Oxazolidinones
