Aminoglycosides Flashcards
describe the active transport of aminoglycosides into cells and why this limits their effectiveness under anaerobic conditions
- aminoglycosides are highly polar compounds
- require entry into the cell via an energy-dependent active bacterial transport mechanism that requires oxygen and an active proton motive force
- aminoglycosides work poorly in anaerobic and acidic environments such as abscesses
describe why administration of beta lactams or vanocmycin can enhance effectiveness of aminoglycosides
- aminoglycosides depend on uptake past the cell wall
- uptake of aminoglycosides is enhanced by antibiotics that inhibit bacterial cell wall synthesis
three types of drug effects on protein synthesis
- blocks initiation of protein synthesis
- blocks further translation and elicits premature termination
- incorporation of incorrect amino acid
- binds to 30S ribosome
three mechanisms of resistance
- decreased accumulation via efflux pumps
- bacterial enzymes modify the drug and prevent it from binding to ribosomes
- mutation of the bacterial ribosome in such a way that aminoglycosides can no longer bind
indication for spectinomycin
- alternative treatment for drug-resistant gonorrhea in penicillin-allergic patients
class of microbes which aminoglycosides act against and 4 diseases caused by this class
- gram negative aerobic bacteria
- diseases include pneumonia, UTIs, septicemia, CNS infections
microbe that is susceptible to tobramycin
- pseudomonas aeruginosa
where are aminoglycosides accumulated and their side effects
- accumulate in renal cortex and endolymph and perilymph of the inner ear
- cause oto and nephrotoxicity
symptoms of cochlear damage
- tinnitis and hearing loss, dizziness
symptoms of nephrotoxicity
- increased BUN and creatinine
3 aminoglycosides used for pseudomonas
- amikacin, gentamycin, tobramycin
two topical uses for neomycin
- minor skin infections
- ophthalmic preparations
