Antimicrobial Therapy 1 Flashcards

1
Q

Antibiotic definition vs. Antimicrobial definition

A

antibiotic- “destructive to life” , a chemical that is produced by one microorganism and tha the ability to harm other microbes

antimicrobial- any agent, natural or synthetic, that has the ability to kill or suppress microorganisms.

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2
Q

Why are antibiotics selectively toxic?

A

If they weren’t the drugs would not only kill the infecting microbes, but also the host cell and therefore have no therapeutic utility.

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3
Q

What is one of the major causes of antibiotic abuse?

A

Overtreatment of acute pharyngitis

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4
Q

What is the only drug that have direct public health consequences for persons other than the one who received the medication?

A

Antibiotics

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5
Q

How do microorganisms become resistant?

A

by alterations in the function or structure

  • spontaneous mutation: random changes in a microbes DNA, usually results in resistance to only one drug
  • Conjugation/plasmid transfer: process by which extrachromosomal DNA (plasmid) is transferred from one bacterium to another. Primarily in gram negative bacteria
  • enzymatic inactivation
  • antibiotic uptake reduction
  • increased antibiotic removal: efflux pumps remove abx from intracellular space
  • alteration of bacterial target sites: the binding site on bacterial cell membrane is altered

**Use of antibiotics promotes the emergence of drug-resistant microbes

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6
Q

What is the role of a beta lactamase?

A

to split the beta lactam ring of penicillin, cephalosporins, carbapenems, monobactams

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7
Q

What are three strategies for delaying emergence of resistant?

A
  1. antimicrobial agents should be used ONLY when actually needed.
  2. narrow-spectrum agents should be be employed whenever possible
  3. Newer antibiotics should be reserved for situations in which older drugs are no longer effective.
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8
Q

What is MIC?

What is breakpoint?

A

MIC- minimum inhibitory concentration, lowest concentration of antimicrobial that inhibits growth of bacteria

Breakpoint- the MIC that is used to designate between susceptible and resistant.

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9
Q

How do you use breakpoint to determine susceptibility?

A

Breakpoint has to be greater than MIC and the greater the difference between them, the more susceptible the organism is to that antibiotic.

ex.
gentamicin: MIC=2, breakpoint=4 —>susceptible
Pip/tazo: MIC=8, breakpoint=32—> susceptible

Pip/tazo is a better choice

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10
Q

What is empiric therapy?

A

assuming what the organism is based on pt history and site in the body.

It is your best guess!

*once the identity and drug sensitivity of the infecting organism has been determined, the patient can be switched to a more selective antibiotic.

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11
Q

To be effective, the antibiotic must be present at the site of infection in a concentration (less/greater) than the MIC.

A

greater

*drug levels 4 to 8 times the MIC are often desirable

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