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Sem 1
Protein inhibitors
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Emily cheung
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Cards (29)
What are protein synthesis inhibitors?
They are substances that interfere with the process of protein synthesis in
bacteria
.
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What is the distinct action of beta-lactams compared to polymyxins?
Beta-lactams inhibit
cell wall synthesis
, while polymyxins disrupt the
bacterial cell membrane
.
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How do antibiotics selectively target bacteria during protein synthesis?
They interrupt processes and enzyme functions that differ between bacterial and
eukaryotic
protein synthesis.
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What is the mechanism of action of aminoglycosides?
Aminoglycosides bind to the
bacterial
ribosome and distort it, preventing
protein synthesis
initiation.
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Name three examples of aminoglycosides.
Gentamicin
, amikacin, and tobramycin.
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Why is serum concentration monitored for aminoglycosides?
To prevent overdose toxicity, which could lead to
hearing loss
.
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What is streptomycin used for?
It is an antibiotic used for the treatment of
tuberculosis
(TB).
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What is the spectrum of activity for aminoglycosides?
Aminoglycosides are active against
Gram-negative
bacteria and
staphylococci
but inactive against
streptococci
and
anaerobes
.
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What are the clinical applications of aminoglycosides?
They are used for life-threatening
Gram-negative
infections, severe skin infections, complicated urinary tract infections, and
sepsis
.
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Name some organisms that cause conditions treated by aminoglycosides.
coli
,
Pseudomonas
,
Chlamydia
,
TB
,
Streptococcus B
, and
Listeria
.
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How do macrolides function as protein synthesis inhibitors?
Macrolides bind to the
50S ribosomal subunit
and cause dissociation of
peptidyl-tRNA
.
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What types of bacteria are macrolides primarily used to treat?
They are primarily used to treat
Gram-positive
bacteria.
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What are some examples of macrolides?
Erythromycin
,
azithromycin
, and
clarithromycin
.
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What is the mechanism of action of quinolones?
Quinolones bind to
unpaired DNA bases
and interact with
gyrase
, which is essential for DNA replication.
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What are the generations of quinolones and their characteristics?
1st
generation:
nalidixic acid
;
2nd
generation:
ciprofloxacin
;
3rd
generation:
lomefloxacin
;
4th
generation:
trovafloxacin
.
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What properties may each new generation of quinolone introduce?
Wider
spectrum
of activity, better dosing, fewer drug
interactions
, and fewer side effects.
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What is the mechanism of action of metronidazole?
Metronidazole damages bacterial DNA by producing toxic byproducts in
anaerobic
environments.
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Why does metronidazole not damage human DNA?
Human DNA does not respire
anaerobically
and cannot
metabolize
metronidazole.
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How is metronidazole activated in the body?
It is activated in the presence of
pyruvate: ferredoxin oxidoreductase
(
POR
), reducing it to a nitro radical anion.
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What is the role of tetrahydrofolic acid in bacteria and mammals?
Tetrahydrofolic acid is essential for
nucleotide synthesis
in both bacteria and mammals, but synthesized differently.
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How does trimethoprim selectively inhibit bacterial tetrahydrofolic acid synthesis?
Trimethoprim binds to bacterial
dihydrofolate reductase
(DHFR)
50
times more effectively than the mammalian form.
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What is the principle of the broth dilution test in antimicrobial susceptibility testing?
The broth dilution test measures the
minimum inhibitory concentration
(MIC) by determining the lowest concentration that prevents
bacterial growth
.
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What is the disk diffusion method in antibiotic susceptibility testing?
In disk diffusion, antibiotics diffuse into agar, creating a
concentration gradient
that inhibits the growth of sensitive
organisms
.
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What are antibiotic breakpoints?
Antibiotic breakpoints are
empirical
predictions of resistance based on whether the
zone of inhibition
falls above or below a specified diameter.
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Why is a fully-quantitative MIC not possible with the disk-diffusion technique?
Because
antibiotic
diffusion through agar is radial, not linear, making it difficult to
quantify
precisely.
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What are new and emerging methods for ascertaining resistance?
They involve
molecular
and
genetic
methods to identify specific
resistance genes
, negating the need for
phenotypic MIC testing
.
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What is the significance of antimicrobial resistance in healthcare?
Antimicrobial resistance impacts various branches of medicine, including
surgery
, cancer
chemotherapy
, and routine procedures.
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How does the presence of antimicrobial-tolerant strains lead to resistance?
Sustained exposure to
antibiotics
allows tolerant strains to
replicate
, leading to increased resistance over time.
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What is the projected impact of antimicrobial resistance by 2050?
Antimicrobial resistance deaths are projected to surpass current
mortality rates
if no action is taken.
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