L25: Aminoglycosides Flashcards
(40 cards)
Which five drugs are aminoglycosides (hint: ST GAP)?
S - Streptomycin
T - Tobramycin
G - Gentamycin
A - Amikacin
P - Plazomicin
The bacteria 70S ribosomes (composed of 2 main subunits: 30S and 16S RNA subunit + 21 proteins) is targeted by which two drug classes?
1) Tetracyclines
2) Aminoglycosides
Aminoglycosides bind irreversibly to ___S to block protein synthesis. They are also ____, especially in combination
A. 30S, bacteristatic
B. 50S, bactericidal
C. 30S, bactericidal
D. 50S, bacteristatic
C. 30S, bactericidal
To enter into the bacterial cell, aminoglycosides diffuse through the porin channels in the outer membrane
of gram __ bacteria. Also
cross the plasma membrane of the bacteria by an
___-dependent, active transport process
A. Gram (-) ; O2 dependent
B. Gram (+) ; O2 dependent
C. Gram (+) ; CO2 dependent
A. Gram (-) ; O2 dependent
This active transport by which aminoglycosides crosses the plasma membrane of the bacteria is inhibited by __ pH and by
____ conditions
low ; anaerobic
True or False: Aminoglycosides are not effective against anaerobic
bacteria or in the acidic pH of an abscess
True
Antibiotics that inhibit bacterial cell wall synthesis ___
the transport of aminoglycosides into the bacteria
A. diminish
B. enhance
B. enhance
What type of effect is seen with an aminoglycoside + beta-lactam?
A. Additive
B. Synergistic
C. Antagonistic
D. Nihilistic
A. Synergistic
Aminoglycosides have best activity against?
A. Gram (-) Aerobic
B. Gram (-) Anaerobic
C. Gram (+) Aerobic
D. Gram (+) Anaerobic
A. Gram (-) Aerobic
Although Gentamicin and Tobramycin have some activity against S. aureus/ S.epidermidis, you should not use ____ alone for serious
Staph
aminoglycosides
Aminoglycosides are often used with a ____ antibiotic
for better coverage against gram (+)
beta-lactam
True or False: Gentamicin/
Streptomycin are used with a beta-lactam
(Penicillin G) to get a synergistic effect against Entercocci spp
True
Aminoglycosides are combined with β-lactams or vancomycin for ____
Gram-positive
endocarditis
What are the 5 clinical uses of aminoglycosides?
- Gram (-) Enteric Infections
- Tb
- P. aeru
- Opthalamic - ocular bacterial infections, conjunctivitis, corneal ulcers
True or False: Aminoglycosides are effective for abscesses or anaerobes
False - ineffective for abscesses or anaerobes
Aminoglycosides are very polar – therefore: found in high concentrations in
___ but not so much other tissues
kidney
True or False: Ceftriaxone preferred for meningitis
True
True or False: Aminoglycosides use concentration-dependent killing
True
____: ~3 hr period after drug below MIC
where effect still present – allows for less frequent dosing
with no lapse in killing + higher efficacy with less toxicity
(as seen in aminoglycosides)
Postantibiotic effect
For aminoglycosides, high [drug] in renal cortex and inner ear – leads to ____ and ____
nephrotoxicity and ototoxicity
Why is nephrotoxicity so common with aminoglycoside use?
- PCT selectively take up
drug via megalin
Decreased renal function is so common
with aminoglycosides that oral dosing regimens take this into account by doing what?
Lower the dose to compensate
for lowered drug elimination
Ototoxicity is an irreversible side effect of ____ use
aminoglycoside
