AM - Antibiotic Action Flashcards

1
Q

What are the 3 ways antibiotics act?

A
  • Inhibiting Cell Wall Synthesis
  • Inhibiting Protein Synthesis
  • Inhibiting Nucleic Acid Synthesis
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2
Q

example of antibiotics that inhibit cell wall synthesis?

A

Penicillins, Cephalosporins & Glycopeptides

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3
Q

Example of antibiotics that inhibit protein synthesis?

A

Aminoglycosides (Gentamicin)
Macrolides (e.g. Erythromicin)
Tetracycline
Oxazolidinones (Linezolid)
Cyclic Lipopeptides (Daptomycin)

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4
Q

Example of antibiotics that inhibit nucleic acid synthesis?

A

Quinolones
E.g. Ciprofloxacin & Nalidixic acid

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5
Q

Why dont cell wall synthesis inhibitors affect human cells?

A

Because they lack cell walls

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6
Q

How do B-lactams work?

A
  • Bind to PBPs
  • Inhibits carb chain cross-linking
  • Peptidoglycans can’t be formed
  • Autolytic enzymes kill the cell
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7
Q

What are PBPs?

A

Penicillin Binding Proteins
Enzymes that synthesize cell wall

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8
Q

What was the first antibiotic discovered?

A

Penicillin G [Benzyl Penicillin]

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9
Q

Why are many gram -ve bacteria resistant to Benzyl Penicillin?

A

Gram -ve bacteria have a relatively impermeable cell wall.

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10
Q

How are cephalosporins generally grouped?

A

By Generations (usually chronological)

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11
Q

How do Glycopeptides inhibit cell wall synthesis?

A

Inhibits assembly of peptidoglycan precursors

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12
Q

On what bacteria do glycopeptides act?

A

Glycopeptides act on Gram +ve bacteria

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13
Q

Examples of Glycopeptides?

A

Vancomycin & Teicoplanin

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14
Q

Why are glycopeptides delivered parenterally?

A

Theyre not absorbed in the gut

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15
Q

Whats the dosage regime for Teicoplanin?

A

Once daily

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16
Q

Compare Vancomycin & Teicoplanin?

A

Teicoplanin is less toxic
Same spectrum of activity

17
Q

Why must an IV vancomycin infusion be carefully monitored?

A

Its extremely toxic and can cause tissue damage if it leaks out the veins.

18
Q

Possible side effects of vancomycin?

A

Ototoxicity
Nepthrotoxicity
Skin Rashes

19
Q

Why do we monitor Vancomycin trough levels?

A

To ensure its level stays within therapeutic range

20
Q

Why don’t protein synthesis inhibitors affect humans?

A

There are differences between the bacterial & mammalian ribosomes

21
Q

What 4 types of protein synthesis inhibitors are there?

A

Aminoglycosides
Macrolides & Tetracyclines
Oxazolidinones
Cyclic Lipopeptide

22
Q

What do aminoglycosides treat?

A

Gram -ve bacteria & sometimes Staphylococci

23
Q

How are aminoglycosides administered?

A

Parenterally rather than orally

24
Q

Whats the most common aminoglycoside?

A

Gentamicin

25
Q

What are the possible side effects of Gentamicin & how do we avoid them?

A

Ototoxicity & Nephrotoxicity
Using a careful dosing regime & serum level monitoring

26
Q

What are common macrolides & what do they treat?

A

Erythromicin & Clarithromicin
Treat gram +ve infections when people are penicillin allergic

27
Q

What bacteria are often resistant to macrolides?

A

Many staphylococci & Streptococci are resistant to macrolides

28
Q

Whats the only common oxazolidinone?

A

Linezolid
Given orally
Treats MRSA

29
Q

Whats the main Cyclic Lipopeptide & what does it treat?

A

Daptomycin
Treats gram +ve bacteria, mainly MRSA

30
Q

In what two ways do antibiotics inhibit nucleic acid synthesis?

A

By interferin directly in the process
By blocking supply of precursors

31
Q

What are the 2 common categories of Nucleic acid syntehsis inhibtors?

A

Co-Trimoxazole
Fluoroquinolones

32
Q

What makes up co-trimoxazole?

A

Trimethoprim & sulphamethoxazole

33
Q

Why is co-trimoxazole used to treat chest infection?

A

Co-trimoxazole is used for chest infections because its less likely than cephalosporins to cause a CDI

34
Q

What is trimethoprim alone used to treat?

A

Urinary Tract Infections

35
Q

Example of a fluoroquinolone?

A

Ciprofloxacin, directly inhibits DNA synthesis.
Most effective against Gram -ve

36
Q

Why cant ciprofloxacin be used in kids?

A

It interferes with cartilage growth

37
Q

How is ciprofloxacin delivered?

A

Orally or Parenterally

38
Q

Example of a newer quinolone?

A

Levofloxacin

39
Q

What is levofloxacin used for?

A

Treating chest infections
Its more effective than older quinolones like ciprofloxacin against gram +ve bacteria.