aminoglycoside Flashcards
What is the structure of aminoglycoside antibiotics?
Aminoglycosides contain an aminocyclitol moiety linked to aminosugars.
What is the first aminoglycoside antibiotic discovered?
Streptomycin, discovered in 1939.
List some aminoglycoside antibiotics closely related to streptomycin.
- Kanamycin
- Neomycin
- Paromomycin
- Gentamicin
- Tobramycin
- Netilmicin
- Amikacin
How are aminoglycosides primarily absorbed when administered orally?
They are absorbed very poorly (less than 1%).
What are the main side effects of aminoglycosides?
- Ototoxicity
- Nephrotoxicity
What is the significance of aminocyclitols in aminoglycosides?
They are cyclohexanes with amino and hydroxyl groups that provide high water solubility.
How do aminoglycosides distribute in the body?
They distribute well into most body fluids but not into the CNS, bone, or fatty tissues.
What is the primary mechanism of excretion for aminoglycosides?
They are excreted by glomerular filtration.
What types of infections are aminoglycosides effective against?
- Systemic infections caused by aerobic G(-) bacillus
- Tuberculosis
- Brucellosis
- Tularaemia
- Yersinia infections
True or False: Aminoglycosides are effective against anaerobic bacteria.
False.
What are R factors in microbial resistance to aminoglycosides?
Extrachromosomal R factors are responsible for producing aminoglycoside deactivating enzymes.
Name the types of aminoglycoside deactivating enzymes.
- Aminoacetyltransferases (AAC)
- Phosphotransferases (APH)
- Nucleotidyl transferases (ANT)
What does AAC do to aminoglycosides?
AAC acetylates specific amino groups on the drug.
What does APH do to aminoglycosides?
APH phosphorylates hydroxyl groups on the drug.
What does ANT do to aminoglycosides?
ANT adenylates hydroxyl groups on the drug.
What is Amikacin derived from?
Amikacin is a semisynthetic derivative of kanamycin A.
What is the minor mechanism for microbial resistance to aminoglycosides?
Decreased uptake due to blockade in the active transport process.
What role do bivalent cations play in aminoglycoside resistance?
They compete with aminoglycosides during the uptake process.
What is the significance of ring I in aminoglycosides?
Ring I is necessary for broad-spectrum antibacterial activity.
What happens when the 3-OH and/or 4-OH groups are omitted in kanamycin?
Antibacterial activity remains but increases resistance against AAC.
What is the mechanism of action of aminoglycosides?
They inhibit protein biosynthesis by attaching to the 30s portion of ribosomes.
What is the role of positive charge in aminoglycosides?
It aids absorption through the outer membrane of G(-) bacteria.
What is the therapeutic use of Kanamycin?
Used for treating GI infections and systemic G(-) bacillus infections.
Fill in the blank: The least toxic member of the aminoglycosides in the market is _______.
kanamycin A
