drugs affecting 30S
aminoglycosides and tetracylcines
drugs affecting 50S
macrolides and some others
amikacin, neomycin, gentamicin, streptomycin, tobramycin
IM, IV only!; bind to 30S and interfere with protein synthesis
adenylating, acetylation or phosphorylation of aminoglycosides
aminoglycosides side effects
WORST! renal toxicity; vestibular ototoxicity; neuromuscular jxn - force Ca out and can cause problems (myasthenia gravis or hypocalcemia); **post-antibotic effects and [ ] dependent killers!!!** = decrease side effects by dosing high once and then decreasing doses
tx gram - infections
TOXIC, only used in cream
doxycycline, tetracycline, tigecycline
broad spectrums; over-used and now fxnlly narrow spectrum; all equally effective (doxy = longest 1/2 life!)
bind to 30S; affects eukaryotic, but prokaryotic much better
bacterial gain efflux pumps by conjugation
used for rocky mountain spotted fever and for spirochetal infections - lympe and relapsing fever
tetracyclines adverse effects
discolorations of teeth and bone; phototoxicity; block absorption - don't take with food; decay over time - DO NOT use expired!!
azithromycin** (not prescribed as an antibiotic, now for for GI stim), clarithromycin, erythromycin, telithromycin (ketolide), clindamycin (lincosamide)
block fxn of 50S ribosomal subunit; block peptidyl transferase and translocation step; nice broad spectrum; LEAST side effects!!
increased drug transport out of bacteria (efflux); mutations in the 50S that decrease binding of drug
prolonged QT; are potent inhibitors of P450s!!
SERIOUS side effects - life threatening; readily crosses BBB; tx for meningitis!! use in 3rd world countries
blocks 50S; blocks peptidyl transferase
idiosyncratic aplastic anemia
gray baby syndrome
quinupristin/dalfopristin; inhibit protein synthesis; used for VRE; prescribed together; $$
bind to P site on 50S; for Gram +
VRE, nosocominal pneumonia, complicated skin infections
MOA inhibitors - be careful!