10 Questions
What is the main mechanism of action of aminoglycosides?
Binding to 30s subunits leading to altered anticodon sequence of tRNA
Why are aminoglycosides not administered orally?
Due to their poor gastrointestinal absorption
What is the primary reason for reserving aminoglycosides for severe systemic infections?
Their high toxicity profile
What is the primary mechanism of resistance to aminoglycosides?
Alteration of 30s subunit binding site
What is a common adverse effect of aminoglycosides?
Nephrotoxicity
At which ribosomal binding site does Clindamycin bind?
50S
What is the effect of Clindamycin on toxin production by GAS and S. aureus?
It inhibits toxin production
What is the activity of Clindamycin against staphylococci and streptococci?
Concentration-dependent bactericidal
What is the class of antibiotics that Clindamycin belongs to?
Lincosamide
What is the activity of Clindamycin against anaerobes?
Concentration-dependent bactericidal
Study Notes
Aminoglycosides
- Bactericidal antibiotics that bind to 30S subunits, altering the anticodon sequence of tRNA
- Mainly effective against Gram-negative bacilli and Staphylococcus species
- Administered systemically, primarily via intramuscular (IM) injection
- Not administered orally (except for neomycin) due to poor gastrointestinal absorption
- May cause ototoxicity, nephrotoxicity, and respiratory depression
- Reserved for severe systemic Gram-negative infections
- Excreted in the urine, requiring dosage adjustment
- Effective in topical ophthalmic use, but only for short-term therapy (5-7 days)
Mechanisms of Resistance
- Alteration of 30S subunit binding site
- Change in cell membrane permeability
- Enzymatic inactivation
Adverse Effects
- Vestibular and auditory dysfunction
- Nephrotoxicity (tubular necrosis)
- Respiratory depression (neuromuscular paralysis)
Clindamycin
- Lincosamide class of antibiotics
- Binds to 50S ribosomal binding site, similar to macrolides
- Inhibits production of toxic-shock and other toxins by GAS and S. aureus at low concentrations
- Exhibits concentration-dependent bactericidal activity against:
- Staphylococci
- Streptococci
- Anaerobes
- H. pylori
- Bacteriostatic agent, but can be bactericidal at high concentrations
This quiz covers the basics of aminoglycosides, a class of antibiotics that bind to 30S subunits, affecting gram-negative bacteria and staphylococci. Learn about their administration, side effects, and uses.
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