Antibiotics ✅ Flashcards

1
Q

What groups can antibiotics be divided into?

A
  • Beta-lactam agents
  • Macrolides
  • Tetracyclines
  • Aminoglycosides
  • Glycopeptides
  • Fluoroquinolones
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2
Q

What can beta-lactam agents be further divided into?

A
  • Penicillins
  • Cephalosporins
  • Carbapenums
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3
Q

Give 4 examples of penicillins

A
  • Penicillin
  • Flucloxacillin
  • Amoxicillin
  • Piperacillin
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4
Q

Give 2 examples of cephalosporins

A
  • Ceftriaxone

- Cefuroxime

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5
Q

Give 2 examples of carbapenums

A
  • Meropenum

- Imipenum

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6
Q

Give 3 examples of macrolides

A
  • Erythromycin
  • Azithromycin
  • Clarithromycin
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7
Q

Give an example of a tetracycline

A

Doxycycline

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8
Q

Give 2 examples of an aminoglycoside

A
  • Gentamicin

- Amikacin

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9
Q

Give 2 examples of glycopeptides

A
  • Vancomycin

- Teicoplanin

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10
Q

Give an example of a flouroquinolone

A

Ciprofloxacin

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11
Q

What does pharmacokinetics describe?

A

The change in drug and metabolite concentrations in the body over time

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12
Q

What does pharmacodynamics consider?

A

The concentration of a drug at the site of action and the effect it produces on that site, both in terms of clinical effect and adverse effects, at different concentrations

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13
Q

Why is it important to understand pharmacokinetic-pharmacodynamic profiles for antimicrobial drugs?

A

It guides dosage and dose frequency

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14
Q

What factors decide dose frequency of antibiotics?

A
  • Half life

- Mechanism of action of antibiotic

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15
Q

Give an example of an antibiotic with a short half life

A

Penicillins

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16
Q

What is the implication of an antibiotic having a short half life?

A

It needs to be given more frequently

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17
Q

Give an example of an antibiotic with a very long half life?

A

Azithromycin

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18
Q

What aspect of a drugs mechanism of action is important when considering dosing intervals?

A

The way the activity of a drug is affected by it’s concentration

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19
Q

In what ways may the activity of a drug be affected by it’s concentration?

A
  • Activity may be related to time drug exceeds the minimum inhibitory concentration (MIC)
  • Activity may be related to the peak antibiotic concentration reached
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20
Q

Give an example of an antibiotic whose activity is related to the time that the concentration exceeds the minimum inhibitory concentration

A

Penicillin

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21
Q

Give an example of an antibiotic whose activity is related to the peak antibiotic concentration

A

Gentamicin

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22
Q

What does the therapeutic index of a drug describe?

A

How likely the drug is to cause toxicity to the host

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23
Q

How is the therapeutic index of a drug calculated?

A

The maximum tolerated dose divided by the minimum effective dose

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24
Q

What is the minimum effective dose of an antibiotic determined by?

A

The lowest dose that will give the required MIC at the site of infection

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25
Q

Give an example of class of antibiotic with a high therapeutic index

A

Beta-lactam agents

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26
Q

What is required for antibiotics with a low therapeutic index?

A

Serum level monitoring and dose adjustment

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27
Q

Give an example of a class of antibiotics with a low therapeutic index

A

Aminoglycosides

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28
Q

What are the ways that antibiotics can exert their antimicrobial effects?

A
  • Disruption of bacterial cell wall
  • Inhibition of protein synthesis
  • Inhibition of DNA replication
  • Interruption of microbial chemical pathways
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29
Q

What classes of antibacterial agents exert their actions by disruption of the bacterial cell wall?

A
  • Beta-lactams

- Glycopeptides

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30
Q

How do beta-lactams and glycopeptide agents disrupt the bacterial cell wall?

A

They prevent cross-linkage of peptidoglycan

31
Q

What is peptidoglycan?

A

A key component of the bacterial cell wall

32
Q

What kind of infections are beta-lactams used to treat?

A

Predominantly gram +ve infections caused by Streptococci

33
Q

Which beta-lactam agents have activity against a broader spectrum?

A

Third-generation cephalosporins

34
Q

Give an example of a third-generation cephalosporin

A

Ceftriaxone

35
Q

Are third generation cephalosporins active against gram -ve or gram +ve organisms?

A

Can be either

36
Q

What organisms does ceftriaxone have poor action against?

A
  • Pseudomonas

- Enterococci

37
Q

What kind of bacteria are glycopeptide antibiotics used to treat?

A

Gram +ve bacteria only

38
Q

Why is the use of glycopeptides limited to use against gram +ve bacteria?

A

The large molecules are not able to penetrate the outer membrane of gram -ve bacteria

39
Q

What classes of antibiotic exert their actions by inhibiting protein synthesis?

A
  • Macrolides
  • Tetracyclines
  • Aminoglycosides
  • Clindamycin
40
Q

Where do antibiotics act to inhibit protein synthesis?

A

At the level of the ribosome

41
Q

What is the advantage of antibiotics that inhibit protein synthesis?

A

As a group, they are active against a wide range of bacteria

42
Q

What organisms are covered by macrolides?

A

Similar spectrum to penicillin, but also active against Mycoplasma, Mycobacteria, and Chlamydia

43
Q

What kind of organisms do aminoglycosides have very good action against?

A

Gram -ve

44
Q

Which class of antibiotics inhibit DNA replication?

A

Fluroquinolones

45
Q

How do fluroquinolone inhibit DNA replication?

A

They inhibit enzymes involved in coiling and uncoiling of DNA

46
Q

What kind of organisms do fluroquinolones have good activity against?

A

Gram -ve

47
Q

What kind of organisms do fluroquinolones have poor activity against?

A

Gram +ve organisms such as Streptococci and Staphylococci

48
Q

Give an example of an antibiotic which works by interrupting microbial chemical pathways

A

Trimethoprim

49
Q

How does trimethoprim interrupt microbial chemical pathways?

A

It inhibits the conversion of dihydrofolate to tetrahydrofolate

50
Q

What is the result of trimethoprim inhibiting the conversion of dihydrofolate to tetrahydrofolate?

A

It prevents purine and pyrimidine metabolism

51
Q

Why do bacteria produce their own folate?

A

Because they cannot absorb folate from the host

52
Q

What kind of organisms is trimethoprim active against?

A

Gram +ve and gram -ve

53
Q

Why is trimethoprim most commonly used to treat UTIs?

A

Due to its excretion and high concentrations in the urine compared to blood

54
Q

What can antibiotics be considered narrow or broad spectrum based on?

A

The range of bacteria they are active against

55
Q

When should broad spectrum antibiotics be used?

A
  • When a wide range of bacteria may be responsible for an infection
  • When polymicrobial infection may be present
56
Q

What is meant by bactericidal antibiotics?

A

Ones that kill the bacteria they are effective against

57
Q

Give two classes of antibiotics that are bactericidal

A
  • Beta lactams

- Aminoglycosides

58
Q

Who should bactericidal antibiotics be used in?

A
  • Serious infections

- Immunosuppressed patients

59
Q

What is meant by bacteriostatic antibiotics?

A

They inhibit bacterial growth but do not kill them

60
Q

What do bacteriostatic organisms rely on to kill the bacteria?

A

The immune system

61
Q

Give two bacteriostatic antibiotics or classes of antibiotics

A
  • Tetracycles

- Trimethoprim

62
Q

Where does knowledge of likely sensitivities of bacteria come from?

A
  • Laboratory tests

- Epidemiological data

63
Q

What are the principles of antimicrobial stewardship?

A
  • Only use antibiotics when there is clinical evidence of bacterial infection
  • Obtain cultures before initiation
  • Document route, indication, dose, and duration
  • Review clinical diagnosis and need for antibiotics daily
  • Decide whether to stop, change routes, change antibiotics, continue, or use OPAT
64
Q

Is bacterial resistance innate or acquired?

A

Can be either

65
Q

Give an example of a bacterium that has innate resistance

A

Pseudomonas

66
Q

What is pseudomonas innately resistant to?

A

Penicillin

67
Q

How can bacteria acquire immunity?

A

Through a genetic change which results in a survival advantage, which results in the mutated strain of bacteria outgrowing the sensitive population

68
Q

What is the main driver for emergence of resistant bacteria?

A

Inappropriate and overdose of antibiotics

69
Q

Why is inappropriate and overuse of antibiotics the main driver for antibiotic resistance?

A

Antibiotics exert a considerable selection pressure on bacterial population, favouring populations that are able to withstand them

70
Q

Why is it important to reduce resistance caused by inappropriate use of antibiotics?

A

Due to the shortage of new antibiotics, it is essential to maintain the efficacy of current ones

71
Q

How should the inappropriate use of antibiotics be reduced?

A

Follow principles of selection of antibiotics and antimicrobial stewardship

72
Q

What are the main factors when selecting the most appropriate antibiotic?

A
  • Consideration of most likely organisms causing infection
  • Knowledge of likely sensitivities of the suspected or isolated organism(s)
  • Site of infection
  • Illness severity
  • Immune status of the host
73
Q

When is a bacterium considered resistant to an antibiotic?

A

When its growth cannot be inhibited by a concentration of a drug that is achievable in the blood