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PR3124 CA1 > Lecture 2- bacterial protein synthesis inhibitors > Flashcards

Lecture 2- bacterial protein synthesis inhibitors Flashcards

1
Q

what are the types of 30S protein synthesis inhibitors? (3)

A
  1. tetracyclins
  2. glycylcycline
  3. aminoglycosides
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2
Q

types of 50s protein synthesis inhi (3)

A
  1. macrolides
  2. clindamycin
  3. linezolid
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3
Q

tetracycline MOA

A

enter organism via passive diffusion and transport protein mech (energy dep)
concentrate intracellularly in susceptible org
drug binds reversibly to 30s subunti of bacterial ribosome–> prevent binding of tRNA to A site of complex–> inhibit bacterial protein synthesis

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4
Q

tetracycline absorption? ROA

A

good bioavail
best on empty stomach
oral

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5
Q

what decreases tetracycline absorption? (2)

A
  • dairy prod

- containing divalent and trivalent cations

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6
Q

properties of tetracycline (3)

A
  • bacteriostatic ab
  • activity against broad spectrum of gram pos, gram neg and atypical bacteria and spirochete bac
  • inadequate activity against ps. aeruginosa and proteus
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7
Q

types of tetracycline (3)

A
  1. tetracycline
  2. doxycycline
  3. minocycline
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8
Q

tetracycline elimination

A

by kkdney

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9
Q

doxycycline elim

A

largerly excreted unchanged in bile and urine

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10
Q

minocycline elim

A

extensively met by liver before excretion

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11
Q

type of glycylcycline (1)

A

tigecycline

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12
Q

benefits of glycylcycline over tetra (2)

A
  • expanded spectrum of act

- decreased susceptibility to dev of resistance

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13
Q

what are the mechs of tetracyline resistance glycylcycline is designed to overcome? (2)

A
  • resistance mediated by acquired efflux pump

- ribosomal protection

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14
Q

tigecycline MOA

A

bind to bac 30s ribosome–> block entry to tRNA (similar to minocycline)

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15
Q

why does tigecycline have lower sus to resistance?

A

it has good binding affinity to ribosomes so its less likely to be dislodged by TET O and TET M proteins

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16
Q

ROA of tigecycline

A

IV- poor oral bioavail

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17
Q

tigecycline distribution?

A
  • penetrates well into tissue but low plasma conc

- poor option for bloodstream infection

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18
Q

tigecycline elim?

A

biliary/fecal

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19
Q

what is the spectrum of tigecycline

A
  • MRSA
  • multidrug resistant streptococci
  • vancomycin resistant enterococci
  • extended spectrum beta lactamase gram neg bac
  • community acquired pneumonia
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20
Q

tigecycline and tetra SE (4)

A
  • gastric discomfort
  • effects of calcified tissues- discolouration of teeth eg. grey, temporary stunting of growth
  • hepatotoxicity
  • ## phototoxicity
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21
Q

tigecycline and tetra CI (2)

A
  • pregnant

- < 8yo- may cause permanent teeth discolouration

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22
Q

types of aminoglycosides (5)

A
  • gentamicin
  • streptomycin
  • tobramycin
  • amikacin
  • neomycin
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23
Q

aminoglycosides MOA

A

distort structure of ribosom by binding to them and blocking formation of initiation complex, cause misreading of codons, inihibit translocation

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24
Q

aminoglycosides absorption and ROA

A

poor oral bioavail– parenteral

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25
Q

aminoglycosides clearance

A

renal, need dose adjustt

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26
Q

which drug has post antibiotic effect (PAE)?

A

aminoglycosides

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27
Q

what is PAE

A

even tho drug conc has dropped below MEC, can still see effect mainly coz drug has doen something to bacteria and this bacteria needs to recover

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28
Q

antimicrobial spectrum of aminoglycosides

A
  • broad spectrum

- primarily effective against aerobic gram neg and mycobacteria

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29
Q

wat is aminoglycosides used in combi with

why?

A

beta lactams for therpay of proven or suspected bacterial infections

  • expand spectrum of activity of antimic
  • provide synergistic bacterial killing
  • prevent emergence of resistance to indv agents
30
Q

gentamycin indicatiosn

A
  • for serious gram neg bac infection
  • more active against gram POS cocci than others when used with betalactam
  • combi therapy with penicillin/ceftriaxone to treat enterobacteriaceae
31
Q

tobramycin indication

A
  • pseudomonas aeruginosa
32
Q

amikacin indication

A
  • WIDEST spcetrum

- ineffective against majority gram POS

33
Q

neomycin ROA

A

oral, topical

34
Q

neomycni indication

A
  • toxic
  • topcial against skin infections
  • oral for bowel prep for surgery
35
Q

aminoglycosides adverse effects

A
  • ototoxicity- hearing
  • nephrotox- retention of aminoglycosides by proximal tubular cells
  • neuromuscular paralysis
  • hypersen
36
Q

6 NOs of aminoglycosides

A
  1. no to protein synthesis- inhibit 30s
  2. mainly aerobic gram Neg Org
  3. No to use during pregnancy
  4. No to CSF penetration
  5. Nephro and Oto toxicity
  6. No to oral admin
37
Q

factors that predispose nephro and oto toxicity

A
  • dose
  • duration
  • concomitant use of nephrotoxic drugs
  • elderly
38
Q

resistance to aminoglycosides

A
  • increase efflux pumps reduce effective intracellular conc
  • gram neg bacteria produce aminoglycosides inactivating enzymes
  • some bacteria alter 30s rib subunit
  • low level resistance may result from inhibition of aminoglycosides uptake by bacteria
39
Q

types of macrolides (3)

A
  • erythromycin
  • clarithromycin
  • azi
40
Q

classes of 50s inhibitors (3)

A
  1. macrolides
  2. clindamycin
  3. linelozoid
41
Q

macrolides MOA

A

inihibit protein synthesis by reversibly binding to 50s subunut
inhibit translocation

42
Q

benefits of clari and azi over erythro

A
  • imrpoved acid stability, tissue penetration, braoden spectrum of activity
43
Q

macrolides ROA

A

oral and parenteal

good oral bioavail

44
Q

macrolides indications

A

ATYPICAL microbes

45
Q

macrolides SE (3)

A
  • gastric distress and motility
  • hepato
  • oto
  • prolong QT interval
46
Q

erythromycin ROA

A

oral, IV

47
Q

erythromycin indication

A

against gram pos and neg
treat comm acquired pneumonia
effective against atypical

48
Q

clarithromycin ROA

A

oral

49
Q

clarithromycin indication

A

most active against both pos and neg

higher activity against atypical bac

50
Q

benefit of clarithromycin

A

modified for better GI tolerance compaed to ery

- clari and azi stable in stomach acid and are readily absorbed

51
Q

azithromycin ROA

A

oral, IV

52
Q

azithromycin indication

A

most avtive against resp infections

53
Q

macrolide elim

A

metabolised hepatically

54
Q

disad of macrolides

A

poor CSF penetration, not good for CNS infection

55
Q

macrolides CI

A

hepatic dysfunction

56
Q

macrolides resistance- how is it acquired (2)

A
  • acquire oen of a erm gene resulting in ribosomal methylation, reduced binding of macrolides to 50s rib subunit
  • increased expression of efflux pump
57
Q

what class does clindamycin belong in

A

lincosamide

58
Q

clindamycin indication

A

anaerobic infection

59
Q

clindamycin moA

A

bind exclusively to 50s subunit of bacterial ribosome and inhibit peptide synthesis

60
Q

clindamycin indications

A
  • trat infection caused by gram pos including MRSA and streptococcus and penicillin resistance anaerobic bac
  • good spectrum of activity agaisnt oral pathogens
61
Q

what cant clindamycin be used against

A

CDAD

coz it has high risk for CDAD

62
Q

clindamycin ROA

A

IV, oral

good oral bioavail

63
Q

clindamycin distribution

A

well into fluids

poor entry into CSF

64
Q

clindamycin metabolism

A

hepatic

65
Q

clindamycin adverse effects

A

takew ith full glass of water to reduce esophageal irritaiton. do not lie down immediately
skin rash
CDAD

66
Q

linezolid MOA

A

bidn to bac 23s ribosomal RNA of 50s subunit–> prevent formation of func 70s initiation complex

67
Q

antimicrobial activity of linezolid

A

bactericidal
- against gram pos
- NOT FOR gram neg
wide coverage due to uniqe MOA eg. covers penicillin resistant strains…

68
Q

linezolid ROA

A

IV, oral

69
Q

linezolid distribution

A

widely distri to body

good penetration into CSF and brain tissue

70
Q

pro (2) and cons (2) of linezolid

A

pros

  1. useful agaisnt many multidrug resistant strains
  2. can give oral and IV, outpt

cons

  1. need give over longer period
  2. need to monitor and take blood count
71
Q

linezolid adverse

A
  • GI eg. nausea
  • bone marrow suppression- monitor blood count
  • serotonin syndrome if given with selective serotonicn reuptake inhibitors

PR3124 CA1 (5 decks)

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