anti-biotics: Protein Synthesis Inhibitors

Question 1

protein synthesis inhibitors act on what ribosome subunits?

Answer 1

30s and 50s

Question 2

what are the protein synth. inhibitors?

Answer 2

(AT CELLS)

Aminoglycosides

Tetracyclines

Chloramphenicol

Erythromycin (Macrolide)

Linezolid

Lincosamide (Clindamycin)

Streptogramins

Question 3

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

Answer 3

aminoglycosides

tetracyclines

Question 4

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

Answer 4

Chloramphenicol

Erythromycin (Macrolide)

Linezolid

Lincosamide (Clindamycin)

Streptogramins

Question 5

aminoglycosides will kill bacteria as long as they are what?

Answer 5

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

Question 6

what are the aminoglycoside drugs?

Answer 6

Gentamicin

Neomycin

Amikacin

Tobramycin

Streptomycin

Kanamycin

Netilmicin

Question 7

how do aminoglycosides work?

Answer 7

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

it will inhibit the initiation complex which induces misreading of mRNA

Question 8

how are aminoglycosides administered?

can it be orally?

Answer 8

parentally (intramuscularly and intravenous)

not orally, barely absorbed

Question 9

how can bacterial resistance be acquired to aminoglycoside drugs?

Answer 9

bacterial transferase enzymes inactivate the drug by:

phosphorylation, adenylation, and acetylation

Essentially resistance is acquired by altering the structure of the antibiotic

Question 10

all protein synthesis inhibitors have good activity towards what bacteria?

Answer 10

gram negative aerobic bacilli

Question 11

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

Answer 11

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

Question 12

what bacteria are resistant to aminoglycosides?

Answer 12

anaerobic bacteria and gram + bacteria

Question 13

why cant gram + bacteria be targeted only with aminoglycosides?

what is the work around?

Answer 13

because the cell wall is too thick

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

Question 14

streptomycin is used against what bacteria?

Answer 14

tuberculosis

Question 15

what activity do tetracyclines have?

Answer 15

bacteriostatic activity

Question 16

how do tetracyclines work?

Answer 16

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

Question 17

What are the tetracyclines?

Answer 17

tetracycline

doxycycline

minocycline

demeclocycline

Question 18

how do tetracyclines work?

Answer 18

(STOPS PROTEIN SYNTH.)

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

Question 19

what will demeclocyclin affect in the body?

Answer 19

it will make renal tubules resistant to ADH action

Question 20

for what disease can demeclocycline be used?

Answer 20

to treat small cell carcinoma of the lung

Question 21

how is the spectrum for tetracyclines?

Answer 21

broad

Question 22

tetracyclines will attack what kind of bacteria?

Answer 22

atypical

gram positive and negative, as well as anaerobes

Question 23

give an example of atypical bacteria

Answer 23

Rickettsia

Chlamydea

Mycoplasma

Question 24

what are some side effects that happen with tetracyclines?

Answer 24

• 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)

Question 25

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

Answer 25

- development of efflux pump (encoded by plasmids) • antibacterial goes into the bacteria and by using the pump, it pumps it back out

Question 26

what atypical bacteria will be targeted by tetracyclines?

Answer 26

Ricketsia Chlamydia Mycoplasma

Question 27

how is the spectrum for chloramphenicol?

Answer 27

broad

Question 28

what will chlorampenicol do?

Answer 28

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

Question 29

what are the side effects that come from chloramphenicol?

Answer 29

bone marrow suppression aplastic anemia In pregnancy = gray baby syndrome (cyanosis, vomiting, shock)

Question 30

why is chloramphenicol not used so frequently?

Answer 30

it is highly toxic

Question 31

how do macrolides work?

Answer 31

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

Question 32

for what are macrolides used?

Answer 32

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

Question 33

what are 3 examples of macrolide drugs?

Answer 33

erythromycin azitrhomycin clarithromycin

Question 34

what is the clue to detecting a macrolide antibiotic?

Answer 34

they all end with **-thromycin**

Question 35

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

Answer 35

mehtylation of the 23s subunit in ribosome

Question 36

how do linezolid work?

Answer 36

by binding to 50s subunit in bacterial ribosome

Question 37

when is linezolid used?

Answer 37

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

Question 38

what are the side effects of linezolid?

Answer 38

thrombocytopenia neutropenia

Question 39

what is the antibiotic spectrum of linezolid?

Answer 39

it is narrow

Question 40

what bacteria does linezolid target? give 3 examples

Answer 40

gram + bacteria Staphylococci, Streptococci, Enterococci

Question 41

what is clindamycin mechanism of action?

Answer 41

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

Question 42

when is clindamycin used?

Answer 42

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

Question 43

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

Answer 43

Pseudomembranous colitis\*\*

Question 44

how do you detect Pseudomembranous colitis?

Answer 44

Watery diarrhea, abdominal pain Also known as “Antibiotic-associated diarrhea”

Question 45

why does pseudomembranous colitis occur?

Answer 45

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

Question 46

how do streptogramins work?

Answer 46

they inhibit tRNA synthase

Question 47

when is streptogramins used?

Answer 47

VRSA VRE

Question 48

what is an example of a streptogramin?

Answer 48

Quinupristin-Dalfopristin in combination