Clinical Use of Abx Flashcards

1
Q

Describe why endocarditis is considered to be in a protected local environment. Tx?

A

fibrin/platelet mixture protects from host defense mechs; bactericidal therapy

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2
Q

Describe why intracellular infections are considered to be in a protected local environment. Tx?

A

some bugs thrive intracellularly; need to penetrate these cells eg rifampin, tetracycline, erythromycin

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2
Q

What is a consideration for drugs and the bladder? What drugs should be used?

A
  • some drugs concentrate there, changing susceptibility - quinolones as a group are good EXCEPT moxifloxacin
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3
Q

What does susceptible (S) mean?

A

bacteria will probably respond to the Abx

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3
Q

Describe why abscesses are considered to be in a protected local environment. Tx?

A

drugs can’t penetrate; need surgical drainage

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4
Q

Name 3 susceptibility tests.

A
  1. broth dilution 2. disk diffusion (Kirby-Bauer) 3. E test
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5
Q

What is the MBC?

A

the lowest conc of the Abx that kills 99.9% of the initial inoculum

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5
Q

_____ Abx have MBC concentrations many fold higher than the MIC concentration.

A

Bacteriostatic

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7
Q

What is the MIC?

A

the lowest concentration of Abx that prevents visible bacterial growth

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7
Q

Bacteriostatic Abx have MBC concentrations ____ than the MIC concentration.

A

many fold higher

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8
Q

Describe why meningitis is in a protected local environment. Tx?

A

within the BBB and protected from host defense mechs; bactericidal therapy

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9
Q

What does resistance (R) mean?

A

infection will probably not respond to the Abx

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10
Q

What is the E test?

A

strip containing a gradient of Abx is plated with a bug- clearing makes ellipse shape- where ellipse point meets the strip is the MIC

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11
Q

At ____, the Abx should have a maximal serum conc that exceeds the MIC of the bacteria (Cp>MIC).

A

normal doses

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13
Q

What is the MBC used to determine?

A

bactericidal vs bacteriostatic

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14
Q

Bacteriostatic Abx have _____ many fold higher than the MIC concentration.

A

MBC concentrations

15
Q

What is broth dilution?

A

serial dilutions of Abx in liquid medium that are inoculated with standard #s of bugs- incubated- check growth- look at lowest conc of Abx that prevented growth (MIC)

16
Q

What does MIC stand for?

A

minimum inhibitory concentration

17
Q

Describe why foreign bodies are considered to be in a protected local environment. Tx?

A

they impair host defense mechs and promote attachment/biofilms; remove the foreign body

18
Q

What does MBC stand for?

A

minimum bactericidal concentration

19
Q

At normal doses, the Abx should have a _____ that exceeds the MIC of the bacteria.

A

maximal serum conc

19
Q

How should a chemo pt’s bacterial infection be treated and why?

A

with bactericidals bc they have decreased neutrophils

21
Q

What does intermediate (I) mean?

A

indeterminate or uncertain response given standard dosing

22
Q

Describe why bone infections are considered to be in a protected local environment. Tx?

A

protected from opsonophagocytosis; prolonged therapy with drugs that concentrate in bone eg fluoroquinolones

24
Q

When would you use empiric therapy?

A
  1. life threatening infections 2. outpatient tx
25
Q

What local factor considerations should be made before giving an Abx to a pt?

A
  1. distribution 2. protected local environments 3. the bladder 4. daptomycin and pulmonary surfactant
27
Q

Bactericidal Abx have _____ that are equal to or barely higher than the MIC.

A

MBC concentrations

28
Q

What is the relationship btw daptomycin and S. pneumoniae?

A

does not treat well bc it’s inactivated by pulmonary surfactant

29
Q

At normal doses, the Abx should have a maximal serum conc that exceeds the ____ of the bacteria.

A

MIC

30
Q

What is an antibiogram?

A

a yearly summary of local susceptibility patterns for common pathogens

31
Q

_____ Abx have MBC concentrations that are equal to or barely higher than the MIC.

A

Bactericidal

32
Q

What does Susceptible-dose dependent (SDD) mean?

A

susceptibility depends on dosing regimen (need higher drug exposure)

33
Q

Bactericidal Abx have MBC concentrations that are ______ than the MIC.

A

equal to or barely higher

34
Q

What is the disk diffusion/Kirby-0Bauer test?

A

suspension of bug is plated and Abx disks placed on top- look for diameter of clearing around the disk

35
Q

What 7 host factors need to be considered when giving a drug to a pt?

A
  1. hx of reactions to Abx 2. renal/liver function 3. age (fetus/neonates/young children) 4. genetic/metabolic factors (G6PD, diabetes) 5. pregnancy 6. drug interactions 7. immune status
36
Q

What is empiric therapy?

A

initiation of therapy before a specific diagnosis is made