inhibitors of bacterial protein synthesis Flashcards
what are the 2 binding sites for tRNA in ribosomes?
a p site and an a site
what is the p site in the ribosome responsible for?
INITIATION
what 2 groups of antibiotics blocks this p site?
aminoglycosides (30s)
linezolid (50s)
what group of antibiotics work on the a site
tetracyclines
tell me the MOA of aminoglycosides (besides that they work on the 30s subunit of the p site)
cause misreading (shift in reading frame)
are aminoglycosides bacteriostatic or cidal
both!
what drug
“blocks the 50s at the p site and used to treat VRE and VRSA”
linezolid
what is a major SE of linezolid
bone marrow suppression (esp the platelets)
what type of bacteria are innately resistant to aminoglycosides? why is this?
anaerobic bacteria because the aminoglycosides get into bacterial cells via an O2 dependent uptake
list 4 aminoglycosides
gentamicin
tobramycin
amikacin
streptomycin
what type of bacteria do aminoglycosides work against
gram - rods
if aminoglycosides are water soluble, how are they excreted?
renal elimination
what drug class can cause neuromuscular blockade and decrease Ach (which is kinda like botulism!)
aminoglycosides
what is the only aminoglycoside that can be used topically
neomycin which is in neosporin
what is the mode of resistance to aminoglycosides
bacteria produce conjugating enzymes that cause aminoglycosides to be conjugated faster and eliminated quickly
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”
dalfopristin/quinpristin
what is the combo dalfopristin/quinpristin used to treat
VRSA and VRE
what is the MOA of tetracyclines
prevent elongation of protein synthesis by preventing protein interaction with the a site
overall the tetracyclines have been replaced by macrolides for a lot of diff bacteria, BUT tetracycline is still deff used for…
H pylori
what are 3 tetracyclines
doxycycline
minocycline
demeclocycline (used for SIADH, not as an antibiotic)
which of the 3 tetracyclines is so water soluble that it isn’t really used that much anymore except in densitry
minocycline
the tetracyclines are excreted in the kidney except for..
doxycycline
why do tetracyclines affect the bones and teeth
because they are chelators that bind Ca and Mg
what are the 3 drugs that are known for phototoxicity?
tetracyclines
sulfonamides
quinolones
what is the mode of resistance for bacteria against tetracyclines
bacteria produce pumps to push the drugs out of the cell
what is the MOA for chloramphenicol
works in the 50S to block the formation of the peptide bond (inhibits the activity of peptidyltransferase)
chloramphenicol has ‘PHEN’ in it. what does that mean?
that is lipid soluble! and that it is excreted via the liver and also can get into the BBB
whats another important thing about the pharmacokinetics of chloramphenicol
that it inhibits p450
what drug do you see “gray baby” syndrome in?
chloramphenicol because it is metabolized by the liver and neonates don’t have a mature liver
how do macrolids and clindamycin work?
work in the 50s by blocking translocation
what are 3 macrolids?
“-thromycin”
erythromycin
azithromycin
clarithromycin
what are macrolids used against
gram positive cocci (staph & strep but OBVIII not mrsa)
what drug class classically treats legionella
macrolids
which one of the macrolids is NOT a p450 inhibitor (because the rest of them are)
azithromycin because its more water soluble
if azithromycin is water soluble, what is it also good for
prego women because it wont cross da placenta
which drug group can stimulate motilin receptors?
macrolids
what macrolid is active against macrolid resistant S pneumonia?
telithromycin
what is the mode of resistance of macrolids & clindomycin?
bacteria make methyltransferase and make the macrolid binding site undetetable
what is clindomycin used against
gram + (staph aureus in osteomyelitis) and anaerobic flora
oh, so clindomycin is good for osteomyelitis? great because i have a sickle cell patient with osteomylitis, lets give them clindomycin right now
hell no! what are you crazy?
sickle cell osteomyelitis-salmonella
salmonella is gram - and clindomycin only works on gram +
What is tigecycline used for?
broad spectrum but NOT pseudomonas
can be used for carbapenem resistant enterobacteria
