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ID > Inhibition of the 50S subunit > Flashcards

Inhibition of the 50S subunit Flashcards

1
Q

macrolides

A
  • erythromycin
  • clarithromycin
  • azithromycin
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2
Q

lincosamides

A
  • clindamycin
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3
Q

streptogramins

A
  • quinupristin

- dalfopristin

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4
Q

oxalidones

A
  • Linezolid

- tedizolid

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5
Q
  • protein synthesis inhibitors that “buy” aka bind, to the 30S subunit
A
  • aminoglycosides

- tetracyclines

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6
Q
  • protein synthesis inhibitor that “sells” at th50S ribosomes
A
  • Streptogarmins
  • Erythromycin
  • lincosamides
  • Linezolide
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7
Q
  • broad spectrum protein synthesis inhibitors spectrum coverage
A
  • Macrolides (50s)
  • Chloramphenicol (50s)
  • Tetracyclines (30s)
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8
Q
  • narrow spectrum protein synthesis inhibitors coverage
A
  • aminoglycosides (30s) (-)
  • lincosamide/clindamycin (50s) (+)
  • streptogarmins (50s) (+)
  • oxazolidones/linezolid (50s) (+)
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9
Q
  • biochem and catalysis subunit of protein
A

50S

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10
Q
  • recognition and binding subunit protein
A

30S

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11
Q
  • core structure coantains a 14-membered or 15-membered lactone ring (cyclic ester) as well as 2 sugar units
A

macrolides

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12
Q
  • how does clarithromycin differ from erythromycin?
A
  • methylation of one OH group
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13
Q
  • how does Azihtromycin differ from other macrolides?
A
  • removal of upper ketone group and addition of a methyl substituted nitrogen into the lactone ring
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14
Q
  • Macrolide unstable in acidic pH due to acid-catalyzed intramolecular cyclization involving the C6 OH and the C9 ketone leading to anhydroerythromycin (GI irritant)
A

erythromycin

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15
Q
  • why do clarithromycin and azithromycin have better acid stability?
A
  • structural modification of C60H group and ketone group
    these modifications improve penetration into host cells, increase passage via porins and generally broaden the spectrum of aactivity
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16
Q
  • act by blocking tunnel pore by which growing peptides exit ribosome by binding to proximal part of the exit tunnel
  • backlog develops near P site and then extends to A site
  • bottom line, they inhibit A and P sight functions
  • Do NOT directly block peptidyl transferase activity, peptide bond can still be formed!!!
A
  • Macrolides
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17
Q
  • macrolide with higher activity against intracellular pathogens such as Chlamydia, Legionella, Moraxella, species and Helicobacter pylori compared to erythromycin
A

Clarithromycin

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18
Q
  • macrolide, with the best activity against respiratory infections such as H. Influenzae and Moraxella catarrhalis, S. pnuemoniae
A

Azithromycin

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19
Q

preferred therapeutics for chlamydial infections

A
  • Azithromycin

- Doxycycline

20
Q

used to eliminate corynebacterium diphtheria

A
  • Erythromycin or penicillin
21
Q

used against legionellosis

A
  • fluroquinolones or azithromycin
22
Q

used against mycoplasma pneumonia aka atypicals

A
  • azithromycin or Doxycycline
23
Q

used against mycobacterium avium

- MAC infections

A
  • azithromycin in combo w rifampin and ethambutol
24
Q

macrolides are highly active against….

A
  • CAP
  • STD
  • H. species
25
Q

what do macrolides treat?

***think CALM

A
  • Campylobacter
  • Atypical
  • Legionella
  • Moraxella
26
Q
  • macrolide, only oral doses in the US
  • can take w food
  • eliminated by both renal and hepatic mechanisms
  • half life of 3-8 hours
  • CYP 3A4 inhibition
A

Clarithromycin

27
Q
  • macrolide used for once daily dosing oral and IV formulations
  • tissue concentration exceeds serum concentration by 10 to 100 fold, large Vd
  • eliminated mainly by hepatic systems and minimal CYP 3A4
A

Azithromycin

28
Q

Adverse rxns of macrolides

- think TACO

A
  • Torsade
  • Allergy
  • Cramp
  • Ototoxicity
29
Q
  • structure is 5 membered heterocyclic nitrogen containing ring joined via an amide link to a sugar reside
  • binds 50S residue to inhibit protein synthesis
  • overlaps macrolide binding site
  • affects A to P translocation secondarily via backlog that develops
A
  • LIncosamide…aka Clindamycin
30
Q
  • clindaymycin good coverage

- think CAP

A
  • Cocci
  • Amaerobes
  • Parasites
31
Q
  • no coverage of clindamycin

- think CENA

A
  • C. diff
  • Enterococci
  • Negative gram aerobes
  • Atypicals
32
Q
  • clindamycin metabolism
A

liver, no renal dose adjustments

33
Q
  • streptogarmins coverage

- think MME

A
  • gram positives
  • MRSA/MSSA
  • VRE
34
Q
  • IV admin
  • 1 hours half life
  • P450 inhihition of 3A4
A

streptogarmins

35
Q
  • true inhibitor of peptide bond formation
  • very dangerous side effects, covers gram negs, pos, anaerobes and atypicals
  • inhibited by hepatic metab, so no good for liver issues
  • bone marrow toxicity
  • grey baby syndrome
A

chlorophenicols

36
Q
  • interfere w formation of the 70S fet-tRNA initiation complex
  • no cross resistance w other drugs
  • oral or IV
  • wide distribution including CSF
  • 4-6 hr half life
  • caution in hepatic diseases, doesn’t effect renal issues
  • weak inhibitor of MAO
A
  • Oxazolidones (Linezolidones) (Tedizolid)
37
Q

Oxazolidones coverage

A
  • Aerobic gram pos
  • Staphylococci
  • Enterococci
  • Streptococci
  • NOT used clically against aerobic gram neg bacteria
38
Q

side effects of Linezolid

A
  • serotonin syndrome

- cheese reaction

39
Q

difference in streptogarmins vs. linezolid

A
  • streptogarmins only covers E. Faecium including VRE faecium but NOT E. faecalis, linezolid covers both
40
Q

50S inhibitor MRSA coverage

A
  • Clindamycin
  • Streptogarmins
  • Linezolid
41
Q
  • only 2 50S inhibitors NOT metabolized only by the liver
A
  • Linezolid

- Clarithromycin

42
Q
  • A to P translocation/ejection of already formed peptide

- block peptide exit tunnel at 50S ribosome

A
  • macrolides

- clindamycin

43
Q
  • peptide chain elongation
  • amino acid incorporation
  • block amino acyl tRNA to A site
A
  • streptogarmins (50S)

- tetracyclines (30S)

44
Q
  • formation of initiation complex

- interfering w the formation of 70S fMet-tRNA initiation complex

A
  • Linezolid (50S)
45
Q
  • peptide bond formation

- inhibit peptidyl transferace

A
  • chloramphenicol (50S)
46
Q

trple effect

- initiation, premature termination and incorporationof incorrect amino acid

A
  • aminoglycosides (30S)

ID (14 decks)

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