Flashcards in Antimicorbial: protein synthesis inhibitors Deck (56)
What is selective toxicity?
the drug blocks a reaction that is vital to both
the microbe and host but has greater impact on the microbe
do humans hav e a 70s ribosome?
What is the one drugs that attaches tRNA synthetas?
What protein subunit doe each of the following drugs affect?
What is the selective toxicity of tetracyclines? static or cidal?
1. 70s mitoch. ribosomes, not cytoplasmic ribosomes
How is resistance incurred against tetracyclines?
1. decreased intracellular levels
a. decreased influx
b. increased efflux
2. enzymatic inactivation of drug
3. expression of proteins that
protect ribosomes from drug
What are key points about tetracyclines absorption?
oral is variable
-decreased by divalent and trivalent cations found in dairy and iron supplements
- decreased when gastric pH is elevated
Is the distribution of tetracyclines wide or narrow?
Very wide- accumulation in spleen, bone marrow, bone, dentine, enamel of teeth, crosses BBB and placenta
Where is excretion of most tetracyclines? what are the two exceptions
1. most through kidneys with some bile/reabsorbed
2. a. doxycycline- inactive chelate/conjugate in feces
b. minocycline-metab. by liver and passed in feces.
What are the two most common things treated with tetracyclines?
Who should tetracyclines absolutely not be given to?
pregnant women and children under 8--->discoloration of teeth
What type of superinfection is common with the use of tetracyclines?
Tetracyclines especially effects which drugs?
bactericidal antibiotics (penicillins)
- digoxin, oral anticoagulants, oral hypoglycemics do to effects on liver and kidney
Tigecycline is especially effective against what>
-strains that are get-resistant
-hershey isolate of MRSA
What gourd of drugs should we think if we see it end with acin or micin or mycin? are they static or tidal? irreversible or reversible binding to 30S?
T-F- aminoglycosides have concentration dependent killing with significant PAE?
What accumulates when using amino glycosides?
streptomycin monosomes-->blocks further translation of messages
What spectrum of bacteria are aminoglucosides? combination with what?
1. Gm- aerobes
2. penicillin or vancomycin
How is resistance incurred with amino glycosides?
1. mutant bacterial ribosome
2. decreased uptake or efflux
3. enzymatic inactivation of the drug
How are aminglycosides administered? why? clearance?
1. IM or IV
2. highly polar and poorly absorbed through GI
3. renal clearance
What is distribution like for the amino glycosides?
not well distributed to most cells, eye or CNS
High concentration only in inner ear and renal cortex--> toxicities (reversible)
What limits the use of streptomycin?
When is gentamicin used topically? how is resistance conferred against gentamicin? is the vestibular ototoxicity reversible?
1. burns, wounds, skin lesions
2. poor drug uptake
What is slightly more active against pseudomonas than gentamycin? What else is it often used for?
2. P. aeruginosa RTI w/ cystic fibrosis
What is the semisynthetic derivative of kanamycin and has reduced toxicity? what does it treat?
2. Bugs resistant to gentamicin, treats M. tuberculosis
Widespread use of what during bowel surgeries led to resistance and enter colitis outbreaks? what does this mean>
2. limited to topical and oral use
Is spectinomycin an aminoglycoside? how do we administer?
1. NO!!! aminocyclitol
What type of antibiotics should we think when we see romycin or domycin?
Are macrocodes static or cidal? because of proximity of their sites of action, they competitively inhibit what? G+ or G- more?
2. ribosome binding of