inhibitors of bacterial protein synthesis

Question 1

what are the 2 binding sites for tRNA in ribosomes?

Answer 1

a p site and an a site

Question 2

what is the p site in the ribosome responsible for?

Answer 2

INITIATION

Question 3

what 2 groups of antibiotics blocks this p site?

Answer 3

aminoglycosides (30s)

linezolid (50s)

Question 4

what group of antibiotics work on the a site

Answer 4

tetracyclines

Question 5

tell me the MOA of aminoglycosides (besides that they work on the 30s subunit of the p site)

Answer 5

cause misreading (shift in reading frame)

Question 6

are aminoglycosides bacteriostatic or cidal

Answer 6

both!

Question 7

what drug

“blocks the 50s at the p site and used to treat VRE and VRSA”

Answer 7

linezolid

Question 8

what is a major SE of linezolid

Answer 8

bone marrow suppression (esp the platelets)

Question 9

what type of bacteria are innately resistant to aminoglycosides? why is this?

Answer 9

anaerobic bacteria because the aminoglycosides get into bacterial cells via an O2 dependent uptake

Question 10

list 4 aminoglycosides

Answer 10

gentamicin
tobramycin
amikacin
streptomycin

Question 11

what type of bacteria do aminoglycosides work against

Answer 11

gram - rods

Question 12

if aminoglycosides are water soluble, how are they excreted?

Answer 12

renal elimination

Question 13

what drug class can cause neuromuscular blockade and decrease Ach (which is kinda like botulism!)

Answer 13

aminoglycosides

Question 14

what is the only aminoglycoside that can be used topically

Answer 14

neomycin which is in neosporin

Question 15

what is the mode of resistance to aminoglycosides

Answer 15

bacteria produce conjugating enzymes that cause aminoglycosides to be conjugated faster and eliminated quickly

Question 16

what drugs:
“bind to sites on 50s ribosomal subunit and prevent interaction with acceptor site. decrease the release of completed polypeptide by blocking its extrusion from the ribosome”

Answer 16

dalfopristin/quinpristin

Question 17

what is the combo dalfopristin/quinpristin used to treat

Answer 17

VRSA and VRE

Question 18

what is the MOA of tetracyclines

Answer 18

prevent elongation of protein synthesis by preventing protein interaction with the a site

Question 19

overall the tetracyclines have been replaced by macrolides for a lot of diff bacteria, BUT tetracycline is still deff used for…

Answer 19

H pylori

Question 20

what are 3 tetracyclines

Answer 20

doxycycline
minocycline
demeclocycline (used for SIADH, not as an antibiotic)

Question 21

which of the 3 tetracyclines is so water soluble that it isn’t really used that much anymore except in densitry

Answer 21

minocycline

Question 22

the tetracyclines are excreted in the kidney except for..

Answer 22

doxycycline

Question 23

why do tetracyclines affect the bones and teeth

Answer 23

because they are chelators that bind Ca and Mg

Question 24

what are the 3 drugs that are known for phototoxicity?

Answer 24

tetracyclines
sulfonamides
quinolones

Question 25

what is the mode of resistance for bacteria against tetracyclines

Answer 25

bacteria produce pumps to push the drugs out of the cell

Question 26

what is the MOA for chloramphenicol

Answer 26

works in the 50S to block the formation of the peptide bond (inhibits the activity of peptidyltransferase)

Question 27

chloramphenicol has ‘PHEN’ in it. what does that mean?

Answer 27

that is lipid soluble! and that it is excreted via the liver and also can get into the BBB

Question 28

whats another important thing about the pharmacokinetics of chloramphenicol

Answer 28

that it inhibits p450

Question 29

what drug do you see “gray baby” syndrome in?

Answer 29

chloramphenicol because it is metabolized by the liver and neonates don’t have a mature liver

Question 30

how do macrolids and clindamycin work?

Answer 30

work in the 50s by blocking translocation

Question 31

what are 3 macrolids?

Answer 31

“-thromycin”

erythromycin
azithromycin
clarithromycin

Question 32

what are macrolids used against

Answer 32

gram positive cocci (staph & strep but OBVIII not mrsa)

Question 33

what drug class classically treats legionella

Answer 33

macrolids

Question 34

which one of the macrolids is NOT a p450 inhibitor (because the rest of them are)

Answer 34

azithromycin because its more water soluble

Question 35

if azithromycin is water soluble, what is it also good for

Answer 35

prego women because it wont cross da placenta

Question 36

which drug group can stimulate motilin receptors?

Answer 36

macrolids

Question 37

what macrolid is active against macrolid resistant S pneumonia?

Answer 37

telithromycin

Question 38

what is the mode of resistance of macrolids & clindomycin?

Answer 38

bacteria make methyltransferase and make the macrolid binding site undetetable

Question 39

what is clindomycin used against

Answer 39

gram + (staph aureus in osteomyelitis) and anaerobic flora

Question 40

oh, so clindomycin is good for osteomyelitis? great because i have a sickle cell patient with osteomylitis, lets give them clindomycin right now

Answer 40

hell no! what are you crazy?

sickle cell osteomyelitis-salmonella
salmonella is gram - and clindomycin only works on gram +

Question 41

What is tigecycline used for?

Answer 41

broad spectrum but NOT pseudomonas

can be used for carbapenem resistant enterobacteria