L25: Aminoglycosides Flashcards
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
What is the most important mechanism for drug resistance?
A. Enzymatic inactivation of drug
B. Impaired drug influx
C. Loss or mutation of ribosomal target protein
(streptomycin)
A. Enzymatic inactivation of drug
- Phosphorylation
(aminoglycoside kinases)
-Adenylation acetylation
(mediated by transferases)”
____ is most resistant to these enzymes used to inactivate drugs in aminoglycosides
Amikacin
Permanent vertigo/loss of balance is common with use of which drug?
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentomycin
C. Streptomycin
___ is second line drug for Tb and use in pregnancy can lead to fetus that is deaf
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
C. Streptomycin
____ is a mix of C1, C1a, C2 and is used to treat resistant streptococci/enterococci via: combo
with cell wall agents
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
D. Gentamycin
True or False: While gentamycin given IV can be used to treat meningitis, the condition is usually treated with 3rd gen cephs
True
Which of the following
can treat gram (-) hospital-acquired UTIs and P. aeruginosa sepsis?
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
D. Gentamycin
____: Similar spectrum to gentamycin; cross-resistance
possible but not guaranteed
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
A. Tobramycin
Tobramycin a little better for _____
____ resistant to tobramycin
P. aeruginosa
E. faecium
Which is more nephrotoxic: gentamicin or tobramycin?
gentamicin
Which of the following is inhaled in fixed dose for P.aeruginosa in cystic fibrosis??
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
A. Tobramycin
____: Kanamycin derivative, less toxic but
may be cross-resistance to kanamycin.
Generally used for bugs resistant to gentamicin/tobramycin
A. Tobramycin
B. Staphylomycin
C. Streptomycin
D. Gentamycin
E. Amikacin
E. Amikacin
Amikacin treats Gram (-) microbes, such as…
Pseudomonas
____ is composed of A, B, C, and small proportion of others; ____ is neomycin E
In both cases, hypersensitivity is common
Neomycin; Paromomycin
True or False:
Neomycin is NOT used
parenterally but Paromomycin can be used parenterally/
topically (parasitic infections)
True
_____ is the newest aminoglycoside to be approved. It is resistant to inactivating enzymes and used to treat complicated UTI’s.
