AM- Mechanisms of Resistance and Issues Flashcards

1
Q

What are the types of resistance?

A

Inherent or intrinsic

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2
Q

What may all strains of a given species be?

Examples?

A

Naturally resistant to an antibiotic

  • Streptococci always resistant to ahminoglycosides
  • Gram negative always resistant to Vancomycin (due to the inability of the drug to penetrate the bacterial cell wall to exert its action)
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3
Q

What may be present in some strains of a species but not in others?

A
  • Acquired resistance.

- Labaratory sensitivity testing is required to establish the sensitivity of any bacteria isolate from a patient

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4
Q

How can resistance be acquired? (2 ways)

A
  • Spontaneous mutation

- Spread of resistance

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5
Q

How does spontaneous mutation give acquired resistance?

A

Change in structure or function which no longer allows the antibiotic to act

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6
Q

How does spread of resistance give acquired resistance?

A

The gene/s that code for resistance can spread from organism to organism or from species to species

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7
Q

What are current issues in antibiotic resistance?

A

B-lactamase production

- Bacterial enzymes which cleave the B-lactam ring of the antibiotic and renders it inactive

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8
Q

How are B-lactamase produced (2 ways)

A
  • Most hospital strains of Staphylococcus aureus produce B-lactamase.
  • B-lactamases are also common in Gram-Negative bacilli
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9
Q

What are 2 ways to combat B-lactamase?

A
  • Co-amoxiclav

- Flucloxacillin

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10
Q

What is the second issue related to antibiotic resistance?

A
  • Carbapenemase Producing Enterobacteriaceae (CPE) or Carbapenem Resistant Enterobacteriaciae (CRE)
  • extremely resistant gram-negative organisms to the carbapanems
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11
Q

What are highly effective antibiotic agents?

A

Carbapanems which are used for the treatment of severe or high risk bacterial infections

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12
Q

What are all the issues related to antibiotic resistance?

A
  • B-lactamase production
  • Carbapenemase Producing Enterobacteriaceae (CPE) or Carbapenem Resistant Enterobacteriaciae (CRE)
  • Alteration of penicillin binding protein (PBP) target site
  • Glycopeptide resistance
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13
Q

How is the alteration of penicillin binding protein (PBP) target site an issue in antibiotic resistance?

A
  • Micro-organisms develop resistance to B-lactams by changing the structure of their PBP
  • Mutations in PBPs gene result in a modified target site to which B-lactams will no longer bind
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14
Q

Where is alteration of penicillin binding protein found?

A

Any strain of S.aureus that has developed through horizontal gene transfer and natural selection

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15
Q

How is glycopeptide resistance an issu in antibiotic resistance?

A
  • Vancomycin
  • Vancomyin resistant enterococci have emerged
  • In Vancomycin resistant enterococci , the peptidoglycan precursor to which vancomycin normally binds to has an altered structure
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16
Q

What can occur in vancomycin resistant enterococci?

A

This mechanism of resistance might spread from enterococci to S.aureus producing vancomycin resistant S.aureus