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AntiM C > Mechanisms of Action of Antibiotics > Flashcards

Mechanisms of Action of Antibiotics Flashcards

1
Q

What are the 3 different mechanisms antibiotics can use to inhibit or kill bacteria?

A
  1. ) Inhibition of cell wall synthesis (e.g. penicillins & cephalosporins)
  2. ) Inhibition of Protein synthesis (e.g. gentamicin & erythromycin)
  3. ) Inhibition of nucleic acid synthesis (e.g. trimethoprim & ciprofloxacin)
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2
Q

What are the 2 types of beta-lactams?

A

Penicillins and cephalosporins

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3
Q

What do beta-lactams do?

A
  • Disrupt peptidoglycan synthesis by inhibiting the enzymes which are responsible for cross-linking the carbohydrate chains.

INHIBIT CELL WALL SYNTHESIS

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4
Q

What are the enzymes which are involved in cell wall synthesis known as?

A

Penicillin-binding proteins

PBPs

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5
Q

Why are many gram negative organisms resistant to benzyl peniciliin?

A

Due to the relative impermeability of the gram negative cell wall.

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6
Q

What group do penicillins and cephalosporins belong too?

A

Beta-lactams

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7
Q

Why are human cells not disrupted by the action of beta-lactams?

A

They have no cell wall. Beta-lactams disrupt cell wall synthesis.

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8
Q

What are the 2 groups of antibiotics that inhibit cell wall synthesis?

A
  • beta-lactams

- glycopeptides

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9
Q

What are the 2 glycopeptides in clincial use?

A

Vancomycin

Teicoplanin

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10
Q

What do vancomycin and telcoplanin (glycopeptides) do to kill or inhibit bacteria?

A

Inhibit assembly of peptidoglycan precursor

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11
Q

What type of bacteria do vancomycin and teicoplanin (glycopeptides) act on?

A

Gram positive bacteria only.

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12
Q

Why are vancomycin and teicoplanin (glycopeptides) usually only given parenterally?

A

They are not absorbed in the GI tract.

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13
Q

What is one of the negatives of Vancomycin use?

A

It is toxic.

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14
Q

Why must iv Vancomycin be given carefully?

A

If it leaks from the veins it can cause damage to the surrounding tissue.

Must be given enough to be theraputic but not too much as to be toxic.

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15
Q

What are some of the side effects of Vancomycin?

A
  • Skin rash
  • Ototoxicity
  • Nephrotoxicity
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16
Q

What is ototoxicity and nephrotoxicity?

A

ototoxicity - toxic to ears

nephrotoxicity - toxic to the kidneys.

17
Q

What are the antibiotics which are involves in the inhibition of protein synthesis?

A
  • Aminoglycosides
  • Macrolides & Tetracyclines
  • Oxazolidinones
  • Cyclic Lipopeptide
18
Q

What types of bacteria can Aminoglycosides usually work on?

A
  • Gram negative bacteria
  • Most staphylococci

NOT streptococci

19
Q

What is the most common aminoglycoside?

A

Gentamicin

20
Q

What is the negative of gentamicin use?

A

Gentamicin is toxic, so it requires a careful dosing regime and monitoring of levels.

21
Q

What are macrolides useful in?

A

Treatment of gram positive infections in patients that are allergic to penicillin.

22
Q

What is a negative of macrolide use?

A

A signifiant percentage of staph. aureus, strep. ptogenes and strep. pnuemoniae strains are resistant. (This must be determined through testing).

23
Q

What is the name of the common oxazolidinone?

A

Linezoid

24
Q

What is linezoid useful in?

How is it given?

A
  • Treatment of MRSA / serious infections

- Orally

25
Q

What is the common cyclic lipopeptide?

A

Daptomycin

26
Q

What is daptomycin used in?

A

Treating gram positives and MRSA/ serious infections.

27
Q

What are the types of antibiotics which inhibit the synthesis of nucleic acids?

A
  • Trimethoprim & sulphamethoxazole

- Fluoroquinolones

28
Q

What do trimethoprim and sulphamethoxazole do to inhibit nucleic acid synthesis?

A

Inhibit steps in purine synthesis.

29
Q

What are trimethoprim and sulphamethoxazole used in conjuction with?

A

co-trimoxazole

30
Q

Why was the use of co-trimoxazole discouraged previously but is becoming more widely used now?

A
  • Discouraged due to side effects

- Increase in use because it is less likely to cause C. diff infections than other broad spectrum agents.

31
Q

What is Trimethoprim used to treat on its own?

A

UTIs

32
Q

What is a common fluroroquinolones?

A

Ciprofloxacin

33
Q

How does ciprofloxacin work?

How is it taken?

A

Direct inhibition of DNA synthesis

Orally and parenterally

34
Q

What is ciprofloxacin useful against?

A

Gram negative organisms

35
Q

When can ciprofloxacin not be used and why?

A

In treating children, due to the danger it could interfere with cartilage growth.

AntiM C (9 decks)

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