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Microbiology Block 2 > anti-biotics: Protein Synthesis Inhibitors > Flashcards

anti-biotics: Protein Synthesis Inhibitors Flashcards

1
Q

protein synthesis inhibitors act on what ribosome subunits?

A

30s and 50s

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2
Q

what are the protein synth. inhibitors?

A

(AT CELLS)

Aminoglycosides

Tetracyclines

Chloramphenicol

Erythromycin (Macrolide)

Linezolid

Lincosamide (Clindamycin)

Streptogramins

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3
Q

what are the protein synthesis inhibitor drugs that act on the 30s ribosomal subunit?

A

aminoglycosides

tetracyclines

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4
Q

what are the protein synthesis inhibitor drugs that act on the 50s subunit?

A

Chloramphenicol

Erythromycin (Macrolide)

Linezolid

Lincosamide (Clindamycin)

Streptogramins

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5
Q

aminoglycosides will kill bacteria as long as they are what?

A

aerobic bacteria or gram negative bacteria, it does nothing to anaerobic

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6
Q

what are the aminoglycoside drugs?

A

Gentamicin

Neomycin

Amikacin

Tobramycin

Streptomycin

Kanamycin

Netilmicin

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7
Q

how do aminoglycosides work?

A

they will bind to the 30s ribosomal subunit and inhibit bacterial protein synthesis

it will inhibit the initiation complex which induces misreading of mRNA

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8
Q

how are aminoglycosides administered?

can it be orally?

A

parentally (intramuscularly and intravenous)

not orally, barely absorbed

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9
Q

how can bacterial resistance be acquired to aminoglycoside drugs?

A

bacterial transferase enzymes inactivate the drug by:

phosphorylation, adenylation, and acetylation

Essentially resistance is acquired by altering the structure of the antibiotic

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10
Q

all protein synthesis inhibitors have good activity towards what bacteria?

A

gram negative aerobic bacilli

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11
Q

why do aminoglycosides need O2 to take effect in the 30s ribosome of bacteria?

A

because O2 is needed for transport across the inner membrane of bacteria (therefore, bacteria must be aerobes)

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12
Q

what bacteria are resistant to aminoglycosides?

A

anaerobic bacteria and gram + bacteria

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13
Q

why cant gram + bacteria be targeted only with aminoglycosides?

what is the work around?

A

because the cell wall is too thick

this is why aminoglycosides are used with ß-lactam or vancomycin drug (cell wall synthesis inhibitor)

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14
Q

streptomycin is used against what bacteria?

A

tuberculosis

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15
Q

what activity do tetracyclines have?

A

bacteriostatic activity

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16
Q

how do tetracyclines work?

A

they will bind to the 30s subunit blocking +RNA from entering the acceptor site

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17
Q

What are the tetracyclines?

A

tetracycline

doxycycline

minocycline

demeclocycline

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18
Q

how do tetracyclines work?

A

(STOPS PROTEIN SYNTH.)

  • it prevents addition of amino acids to growing peptides
  • blocks aminoacyl t-RNA from binding to mRNA-30s ribosome complex*
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19
Q

what will demeclocyclin affect in the body?

A

it will make renal tubules resistant to ADH action

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20
Q

for what disease can demeclocycline be used?

A

to treat small cell carcinoma of the lung

21
Q

how is the spectrum for tetracyclines?

A

broad

22
Q

tetracyclines will attack what kind of bacteria?

A

atypical

gram positive and negative, as well as anaerobes

23
Q

give an example of atypical bacteria

A

Rickettsia

Chlamydea

Mycoplasma

24
Q

what are some side effects that happen with tetracyclines?

A
  • photosensitivity
  • yellowish-brown discoloration of teeth: because they bind to calcium (not given to children or pregnant)
  • skeletal deformity and frowth retardation

(not given to children (14< or pregnant)

25
Q

what is the mechanism of resistance used by bacteria for tetracyclines?

A
  • development of efflux pump (encoded by plasmids)

• antibacterial goes into the bacteria and by using the pump, it pumps it back out

26
Q

what atypical bacteria will be targeted by tetracyclines?

A

Ricketsia

Chlamydia

Mycoplasma

27
Q

how is the spectrum for chloramphenicol?

A

broad

28
Q

what will chlorampenicol do?

A

it will bind to the 50s subunit of bacterial ribosome and blocks peptidyl transferase action (no synthesis of new peptide bonds)

29
Q

what are the side effects that come from chloramphenicol?

A

bone marrow suppression

aplastic anemia

In pregnancy = gray baby syndrome (cyanosis, vomiting, shock)

30
Q

why is chloramphenicol not used so frequently?

A

it is highly toxic

31
Q

how do macrolides work?

A

bind to 23s of the 50s of bacterial ribosomes and block protein synthase as well as translocation

32
Q

for what are macrolides used?

A
  • URTI (upper resp. tract infection)
  • Treatment of community-acquired Atypical pneumonia:(Legionella, Chlamydia pneumoniae, Mycoplasma**)
  • In patients allergic to penicillins
33
Q

what are 3 examples of macrolide drugs?

A

erythromycin

azitrhomycin

clarithromycin

34
Q

what is the clue to detecting a macrolide antibiotic?

A

they all end with -thromycin

35
Q

what is the mechanism for resistance used by bacteria towards macrolides?

A

mehtylation of the 23s subunit in ribosome

36
Q

how do linezolid work?

A

by binding to 50s subunit in bacterial ribosome

37
Q

when is linezolid used?

A

to treat VRE, MRSA, MRSE, penicillin-resistant pneumococci

38
Q

what are the side effects of linezolid?

A

thrombocytopenia

neutropenia

39
Q

what is the antibiotic spectrum of linezolid?

A

it is narrow

40
Q

what bacteria does linezolid target?

give 3 examples

A

gram + bacteria

Staphylococci, Streptococci, Enterococci

41
Q

what is clindamycin mechanism of action?

A

Blocks peptide transfer (translocation) at 50s ribosomal subunit *

42
Q

when is clindamycin used?

A

Mainly Gram-negative Anaerobes ** (eg. Bacteroides fragilis)

43
Q

what is an important side-effect that occurs with Clindamycin?

A

Pseudomembranous colitis**

44
Q

how do you detect Pseudomembranous colitis?

A

Watery diarrhea, abdominal pain

Also known as “Antibiotic-associated diarrhea”

45
Q

why does pseudomembranous colitis occur?

A

Occurs when GI tract flora is suppressed allowing overgrowth of Clostridium difficile

46
Q

how do streptogramins work?

A

they inhibit tRNA synthase

47
Q

when is streptogramins used?

A

VRSA

VRE

48
Q

what is an example of a streptogramin?

A

Quinupristin-Dalfopristin in combination

Microbiology Block 2 (30 decks)

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