Protein synthesis inhibitors Flashcards
Name oxazolidinones
Linezolid
Mechanism of linezolid
Bacteriostatic
Binds 50S subunit and prevents formation of initiation complex
Spectrum of linezolid
Gram+, MRSA, Vanco-resistant enterococci
Side effects of linezolid
Bone marrow suppression, inhibits monoamine oxidase leading to serotonin syndrome (Don’t treat w/ SSRI)
Resistance to linezolid
Alteration of 23S rRNA of 50S subunit to prevent binding
Name Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Mechanism of Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Bactericidal, prevents formation of initiation complex, causes misreading of mRNA, induces early termination
Spectrum of Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Extended spectrum
Side effects of Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Tubular necrosis: ototoxicity and nephrotoxicity
Resistance to Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Intrinsic: failure of antibiotic to enter cell (needs facilitated transport)
Acquired: acquisition of enzyme to inactivate the drug (amikacin is less suscetible to enzyme)
Notes on Aminoglycosides
Gentamicin, Amikacin, Tobramycin
Poor absorption in GI, usually administered IV, does not cross BBB. REQUIRES ENERGY TO ENTER CELL- TREAT W/ ANTIBIOTIC TO DESTROY CELL MEMBRANE
Name tetracyclines
Tetracyclin, doxycycline, minocycline
Mechanism of tetracyclines
Tetracyclin, doxycycline, minocycline
Bacteriostatic- binds to 30S subunit preventing attachment of aminoacyl-tRNA
spectrum of tetracyclines
Tetracyclin, doxycycline, minocycline
Broad: B. burgdorfei, H. pylori, Mycoplasma, Chlamydia
Side effects of tetracyclines
Tetracyclin, doxycycline, minocycline
Chelates metal ions (Calcium), GI irritation, photosensitivity, discoleration of teet, inhibits bone growth. Don’t prescribe during pregnancy.
Resistance to tetracyclines
Tetracyclin, doxycycline, minocycline
Increased efflux, ribosomal protection proteins protect A site from drug
Notes on tetracyclines
Tetracyclin, doxycycline, minocycline
don’t treat during pregnancy
Mechanism of Chloramphenicol
Bacteriostatic- binds 50S preventing peptide bond formation- kills peptidyltransferase reaction
Spectrum of Chloramphenicol
Extended spectrum- but limited due to toxicity
Chloramphenicol side effects
Toxic, bone marrow depression, aplastic anemia, grey baby syndrome
Resistance to chloramphenicol
Reduces membrane permeability, acetyltransferase modifies drug
Notes on chloramphenicol
don’t use on newborn babies because of immature liver- high likelihood of toxicity
Name macrolides
erythromycin, azithromycin, clarithromycin
Macrolide mechanism
erythromycin, azithromycin, clarithromycin
Bacteriostatic- inhibits translocation by binding to 23S rRNA of 50S subunit
Macrolide spectrum
erythromycin, azithromycin, clarithromycin
Broad- coverage of respiratory pathogens, pharyngitis, pneumonia, otitis media, Chlamydia (single dose)
Macrolide side effects
erythromycin, azithromycin, clarithromycin
GI discomfort, inhibitor of CYP3A4 (except azithromycin), Clarithromycin not safe during pregnancy, Azithro can cause pyloric stenosis in infants
Resistance to macrolides
erythromycin, azithromycin, clarithromycin
Methylation of 23S rRNA site, increased efflux, hydrolysis of macrolides by esterases
Name lincosamide
Clindamycin
Clindamycin mechanism
Bacteriostatic- blocks translocation of 50S ribosomal subunit
Clindamycin spectrum
Gram+, including anaerobic bacteria, skin and soft tissue infections, Acne vulgaris
Clindamycin side effects
Diarrhea, abdominal pain, mucus and blood in stool, superinfection with C. diff
Resistance to clindamycin
Mutation in ribosome methylation of rRNA, cross resistance to macrolides and streptogrammins, enzymes can inactivate the drug
Name Streptogrammins
Quinipristin, Dalfopristin
Streptogrammins mechanism
Quinipristin, Dalfopristin
Combined bactericidal for some organisms, bind 50S to inhibit translocation
Streptogrammins spectrum
Quinipristin, Dalfopristin
Multiple drug-resistant Gram+
Streptogrammins side effects
Quinipristin, Dalfopristin
High incidence of arthalgias, inhibits CYP3A4 and likely has significant drug interactions
Resistance to streptogrammins
Quinipristin, Dalfopristin
Ribosomal methylase inhibits binding of drug, Enzymes inactivate drug, efflux, cross resistance with macrocodes and clindamycin
Notes on streptogrammins
Quinipristin, Dalfopristin
Always treat together.