Aminoglycosides & Macrolides

Question 1

What medications are considered aminoglycosides?

Answer 1

Tobramycin, Plazomicin, Amikacin A, Gentamicin, Neomycin, Streptomycin

Question 2

What is the mechanism of action of aminoglycosides?

Answer 2

-inhibits protein biosynthesis by binding to the 30S ribosomal subunit via the 16S rRNA (ionic bonding) which interferes with the formation of the initiation complex, blocks further translation
-also forms nonsense proteins
-leads to leakage of ions and disruption of the cytoplasmic membrane resulting in cell death

Question 3

What are the resistance mechanisms of aminoglycosides?

Answer 3

metabolism -acetylation, adenylation, phosphorylation via bacteria
Altered ribosomes via point mutations
Altered aminoglycoside uptake

Question 4

What adverse effects are of concern with aminoglycosides?

Answer 4

ototoxicity, nephrotoxicity
-Curare-like effects (rare) -can be reversed via neostigimine or calcium gluconate

Question 5

What type of organisms do aminoglycosides cover?

Answer 5

gram +/- organisms but mainly used to cover gram negative organisms w/penicillins

Question 6

What are the oral aminoglycosides?

Answer 6

Neomycin B, Paromomycin (treats dysentery, dwarf/beef tapeworm)

Question 7

What is a polyketide?

Answer 7

sequential addition of propionate groups to a growing chain
-results in alternating methyl groups

Question 8

What is the mechanism of action of macrolides?

Answer 8

inhibit bacterial protein synthesis by binding reversibly to the P site on the 50S ribosomal subunit inhibiting translocation of peptidyl-tRNA from the A site to the P site

Question 9

What medications are considered macrolides?

Answer 9

Erythromycin, Clarithromycin, Azithromycin
-gram + activity

Question 10

What resistance mechanisms exist with macrolides?

Answer 10

mutation of adenine to guanine at A2058
efflux pump
lactone ester hydrolase induced to. degrade the macrolides by hydrolysis
drug induced production of an RNA methylase