Antibiotics 4 - Aminoglycosides Flashcards Preview

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Flashcards in Antibiotics 4 - Aminoglycosides Deck (27):
1

Core structures of Aminoglycoside (three ex.)

1,3 diaminocyclitol structures

  • Streptidine
  • 2-deoxystreptamine
  • Spectinamine

2

7 Clinically important Aminoglycosides

  • Tobra
  • Strepto
  • Spectino
  • Kana-A
  • Amikacin A
  • Neo-B
  • Genta-C2

TSS-KANG

3

Aminoglycoside MOA (general and specific)

Bind 30S subunit - inhibit protein synthesis

Bind to the 16S rRNA forming the A site = interferes with formation of the initiation complex, blocks translation, and elicits premature termination

4

Aminoglycosides also cause impairment of ______

proofreading functions of the ribosome

(resulting in nonsense protein)

 

**nonsense proteins affect cell wall function

5

What effect do the "nonsense" proteins have on the cell?

They impair the function of the cell wall

 

(causes membrane destabilization, allowing more Aminoglycoside to enter the cell and completely halt protein synthesis)

6

Ultimately, Aminoglycosides cause _______ and ______ resulting in cell death

leakage of ions and disruption of the cell membrane

7

How does the Aminoglycoside get into the cell

Displacement of Mg++ and Ca++ ions that form salt bridges with Phosphate groups (on phospholipids) makes the membrane more permeable.

8

Passage of Aminoglycosides through the cytoplasmic membrane occurs...

via active transport

9

How do bacteria inactivate Aminoglycosides?

acetylation

adenylation

phosphorylation

10

The genes responsible for enzymatic metabolism of Aminoglycosides can be...

 

Many of these enzymes...

...transferred to other bacteria

 

Many enzymes have cross-resistance specificity

11

Aminoglycosides are not metabolized by...

humans

They are largely excreted unchanged via the urine.

12

Three mechanisms for Aminoglycoside resistance in bacteria

  1. Metabolism (acylation, adenylation, and phosphorylation)
  2. Altered ribisomes (16S altered by point mutations)
  3. Altered Aminoglycoside uptake (reverts after drug removal)

13

All Aminoglycosides are ____ and _____

ototoxic (irrev.) and nephrotoxic (rev.)

14

3 Risk factors for ototoxicity of Aminoglycoside use

  1. Other ototoxic drugs (loop diuretics, vancomycin)
  2. Compromised renal function
  3. Genetic vulnerability

15

Aminoglycoside + loop diuretics =

potentiated nephortoxicity of both.

 

Monitor creatinine clearance, discontinue if evidence of ototoxicity appears (dizzy, vertigo, tinnitus)

16

Less common Aminoglycoside effect

Curare-like effects

(requires high dose)

17

Respiratory paralysis can be reversed by ___ or ____

Neostigmine or calcium gluconate

18

Aminoglycoside toxicity is more likely if Tx involves... (4)

  • > than 5 days duration
  • elderly
  • renal impairment
  • high dose

19

Spectrum and use of Aminoglycoside

broad spec (+/-)

but mainly used for Gram -

20

Aminoglycosides are often used in combo with ____

Penicillins

 

but must be administered in different compartments to avoid rxn!

21

Penicillin/Aminoglycoside combo used to treat...

Bacterial endocarditis

22

Streptomycin used to treat...

TB

23

Gentamicin is used for....(4)

UTI

Burns

Some PNAs

Joint/bone infections (caused by susceptible Gram-)

24

Aminoglycoside-resistant bacteria common in...

hospitals.

 

25

Amikacin has retained activity against ____.

 

It's used to treat ____.

Aminoglycoside-resistant strains in hospital.

 

Nosocomial infections.

26

Most aminoglycosides are based on _______

2-deoxstreptamine structure

27

High risk patients should be assed by ______ during aminoglycoside course

serial audiograms