4. Antimicrobials Flashcards

1
Q

What are 4 common target of antibiotics?

A

Cell wall synthesis
Protein synthesis
Cell membrane function
Nucleic acid function

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2
Q

What antibiotics target cell wall synthesis?

A

Glycopeptides

Beta-lactams

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3
Q

What antibiotics target cell membrane function?

A

Polymixins

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4
Q

What antibiotics target protein synthesis?

A

Tetracyclines
Aminoglycosides
Macrolides

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5
Q

What antibiotics target nucleic acid synthesis?

A

Quinolones
Trimethoprim
Rifampicin

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6
Q

What is MOA of penicillin?

A

Binds to penicillin binding protein, preventing cross-linking of peptidoglycan in cell wall.

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7
Q

What is an example of a glycopeptide antibiotic?

A

Vancomycin

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8
Q

What is the MOA of vancomycin?

A

Attaches to side chains of amino acids and prevents them being cross-linked in the cell wall.

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9
Q

What is an example of a quinolone?

A

Fluoroquinolones - Cyprofloxacin

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10
Q

What is the MOA is cyprofloxacin?

A

Inhibits topoiosomerase, causing supercoiling and strand breakage of DNA.

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11
Q

What are 3 types of resistance?

A

Intrinsic
Aquired
Adaptive

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12
Q

What is intrinsic resistance?

A

There is no target or access for the drug, usually permanent.
E.g penicillin won’t work again pseudonomas

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13
Q

What is acquired resistance?

A

Bacterial resistance as a result of acquisition of new genetic material or mutation which aids resistance.
Usually permanent

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14
Q

What is adaptive resistance?

A

Organism responding to stress such as sub-inhibitory level of antibiotics
Usually reversible

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15
Q

What are 3 mechanisms of resistance?

A
  1. Drug-inactivating enzymes
  2. Altered target
  3. Altered uptake
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16
Q

What is an example of drug inactivating enzymes leading to resistance?

A

B-lactamase enzymes produced by organisms which inactivate beta lactam antibiotics.

17
Q

How can altered target lead to antibiotic resistance?

A

If the target enzyme has lowered affinity for an antibacterial drug.

18
Q

What is an example of resistance as a result of an altered target?

A

MRSA - PBP2a

19
Q

How can altered uptake of an antimicrobial lead to antibiotic resistance?

A

Increased efflux via P-glycopeoteins decreases intracellular concentration to sub-inhibitory.

20
Q

What are the 3 mechanisms of horizonal gene transfer of extrachromosomal plasmids in bacteria?

A

Transformation
Transduction
Conjugation

21
Q

How can you measure antibiotic sensitivity?

A

Disc sensitivity testing

22
Q

What is minimum inhibitory conc?

A

The lowest concentration of antibiotic that leads to no antibacterial growth.

23
Q

Which penicillin antibiotic is mainly active against streptococci?

A

Penicillin

24
Q

Which penicillin antibiotic is has activity against gram -ve as well as gram +ve bacteria?

A

Amoxicillin

25
What bacteria is flucloxacillin active against?
Staphylococci and streptococci
26
What antibiotic can be given to overcome beta-lactamase enzyme resistance?
B-lactamase inhibitor + Beta lactam antibioitic | - Co-amoxiclav
27
Why are cephalosporins often used instead of penicillins?
Better at withstanding beta lactamase enzymes
28
What is an example of a cephalosporin?
Cefriaxone -meningitis treatment as enters CSF
29
What must be considered when prescribing vancomycin?
Narrow therapeutic window - therapeutic drug monitoring needed
30
What is the MOA of trimethoprim?
Inhibits folic acid synthesis
31
What is trimethoprim used to treat?
UTI
32
What anti-viral drug is commonly used?
Acyclovir
33
What is the MOA of acyclovir?
Inhibits viral DNA polymerase
34
What is antimicrobial stewardship?
Interventions to improve and measure approprite use of antimicrobials
35
What 4 things does antimicrobial stewardship promote?
- Selection of optimal antimicrobial drug regimen - Appropriate dose - Duration of therapy - Route of administration
36
What is the aim of antimicrobial stewardship?
Achieve optimal clinical outcomes Minimise toxicity and adverse effects Reduce costs of infections Limit the selection for resistant strains
37
What are 3 ways of stewardship intervention?
1. Persuasive - education, reminders, feedback 2. Restrictive - prior authorisation, automatic stop orders 3. Structural - computerised records, rapid lab tests, quality monitoring