Lecture 15 - Antimicrobial mechanisms and Resistance Flashcards

1
Q

Difference between antibiotics and chemotherapeutic agents

A

Antibiotics are naturally-occurring

Chemotherapeutic agents are synthetic

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2
Q

Goal of semi-synthetic drugs
1)
2)
3)

A

1) Alter kinetics
2) Reduce toxicity
3) Broaden antimicrobial spectrum

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3
Q

When might it be useful for a drug to have a short half life?

A

If excreted by the kidneys, for a UTI

Increases the amount of antimicrobial in the urinary tract

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4
Q

Which type of bacterium is Bordatella?

A

Gram - rod

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5
Q

Bordatella intrinsic resistance

A

Intrinsically resistant to penicillin

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6
Q

Phases of bacterial growth curve
1)
2)
3)

A

1) Lag phase
2) Exponential phase
3) Stationary phase

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7
Q

What qualifies an antimicrobial as bactericidal?

A

Kills 99.9% of bacteria

3-log reduction (log10 scale)

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8
Q

When are bactericidal antimicrobials necessary?

A

In immunocompromised patients

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9
Q

Tetracycline structure

A

Four hexagonal carbon rings

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10
Q

Structural difference between penicillin and cephalosporin beta-lactams

A

Penicillin is a beta-lactam ring attached to a pentagonal structure

Cephalosporins are beta lactam ring attached to a hexagonal structure

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11
Q

Tetracycline pharmacokinetics

A

Very short half-life

Excreted in bile

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12
Q

How are tetracyclines excreted?

A

In bile

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13
Q
Penicillin examples
1)
2)
3)
4)
5)
6)
A

1) Penicillin G
2) Penicillin V
3) Ampicillin
4) Methicillin
5) Flucloxacillin
6) Carbenecillin

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14
Q

Penicillin G oral availability

A

Low

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15
Q

Penicillin V oral availability

A

Good

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16
Q

Organisms susceptible to penicillin G

A

Gram + rods, cocci

Gram - cocci

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17
Q

Organisms susceptible to penicillin V

A

Gram +rods, cocci

Gram - cocci

18
Q

Toxicity of penicillin G and V

19
Q

Organisms susceptible to ampicillin

A

Gram + rods, cocci

Gram - rods, cocci

20
Q

Ampicillin oral availability

21
Q

Ampicillin toxicity

22
Q

Methicillin toxicity

23
Q

Organisms susceptible to methicillin

A

Gram + cocci

Targeted against staphylococci

24
Q

Methicillin oral efficacy

25
Organisms susceptible to flucloxacillin
Gram + cocci | Targeted against staphylococci
26
Flucloxacillin toxicity
Low
27
Flucloxacillin oral availability
Good
28
Carbenecillin oral availability
Poor
29
Organisms susceptible to carbenecillin
Gram - rods | Targeted against pseudomonas
30
Antimicrobials used particularly against gram + cocci, EG: staphylococcus
Methicillin, flucloxacillin
31
Antimicrobial particularly used against G- rods, EG: pseudomonas
Carbenicillin
32
Carbenecillin toxicity
Very low
33
Antimicrobials targeting cell wall 1) 2)
1) Beta lactams | 2) Glycopeptides
34
Antimicrobials targeting cytoplasmic membrane 1) 2)
1) Polymixins (antibacterial) | 2) Polyenes (antifungal)
35
Antimicrobials targeting ribosomes 1) 2)
1) Aminoglycosides | 2) Chloramphenicol
36
Antimicrobials targeting nucleic acids 1) 2)
1) Rifamycins | 2) Quinolone
37
Antimicrobials targeting folic acid synthesis 1) 2)
1) Sulphonamides | 2) Trimethoprim
38
Bacteria innately resistant to sulphanomides
Enterococci Can't synthesise folate
39
Can humans synthesise folate?
No
40
Examples of bacteria to be treated with ampicillin
Salmonella | Haemophilus influenzae
41
Which antimicrobial would salmonella and H. influenzae be treated with?
Ampicillin