Therapy for Staph and Strep I Flashcards

1
Q

Concentration dependent

A

Increase the rate of bacterial killing as the antibiotic concentration increases.

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2
Q

Concentration dependent drug examples

A

Lipopeptides (daptomycin), aminoglycosides, fluoroquinolones

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3
Q

Time dependent

A

Killing is predicted by the time that the concentration is above a certain level called the MIC (minimum inhibitory concentration)

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4
Q

Time dependent drug examples

A

Beta-lactams, glycopeptides (vancomycin)

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5
Q

MIC

A

Minimum inhibitory concentration, the lowest concentration of an antibiotic that will inhibit the visible growth of bacteria in vitro.

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6
Q

Broth Macrodilution

A

Put different concentrations of antibiotic into test tubes with bacteria. See which one is the first without cloudiness.

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7
Q

E Test

A

Uses a strip with varying doses of antibiotic. Place on a dish, read the zone of inhibition.

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8
Q

Bacteriostatic drugs and example

A

Arrest bacterial growth (linezolid)

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9
Q

Bactericidal drugs and example

A

Kills bacteria (beta lactams, etc).

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10
Q

Is vancomycin bacteriostatic or bactericidal?

A

It depends on the organism!

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11
Q

Beta Lactam Antibiotics

A

Penicillins: Amoxicillin, Ampicillin, Nafcillin, Penicillin

Cefalosporins: Cefazolin (first generation)

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12
Q

How do beta lactams work?

A

Bind to PBPs and inhibit transpeptidases.

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13
Q

What is the best orally absorbed penicillin?

A

Amoxicillin

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14
Q

How are penicillins eliminated?

A

Renally, with the exception of nafcillin.

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15
Q

Natural penicillin is drug of choice for…

A

S. pyogenes, S. galactiae, treponema pallidum (syphilis).

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16
Q

Penicillin G vs Penicillin V

A

Penicillin G is IV preparation whereas penicillin V is acid stable and can be taken orally.

17
Q

Problem with natural penicillin?

A

Susceptible to penicillinases especially in Staph aureus.

18
Q

Anti-staphylococcal penicillin

A

Nafcillin (IV), resistant to penicillinase. No gram-negative activity.

19
Q

Does nafcillin work on gram negative organisms?

20
Q

What organisms does natural penicillin work on?

A

Gram positive cocci, gram negative cocci, gram positive bacilli, spirochetes.

21
Q

Extended Spectrum Penicillins (amino-penicillins)

A

Ampicillin and amoxicillin (both oral).

22
Q

What are amino-penicillins the drug of choice for?

A

Listeria monocytogenes

23
Q

What organisms do amino-penicillins work on?

A

Gram positive organisms, some gram negative activity, some anaerobic activity, ENTEROCOCCI.

24
Q

What must organisms have to be affected by beta lactams?

A

Peptidoglycan wall (mycoplasma is inherently resistant)

25
How is MRSA so drug resistant?
It has an altered PBP that has lower affinity for all beta lactams except ceftaroline.
26
Betalactamase inhibitors
Clavulanic acid, Sulbactam, tazobactam. Abundant in STAPH AUREUS
27
Betalactamase inhibitors combined with beta lactams
Clavulonic acid and amoxicillin = augmentin Sulbactam and ampicillin These have increased gram negative activity.
28
Penicillin hypersensitivity
Penicilloic acid can cause IgE mediated hypersensitivity
29
Penicillin rash common in patients with...
EBV
30
Penicillin diarrhea caused by
alterations in the commensal flora of the GI tract. C diff can overgrow
31
Why isn't methicillin used clinically?
Because it can cause nephritis
32
Cephalosporins
5 generations. Higher generations have increased gram negativity and higher Vd.
33
Cefazolin used for
Gram positive cocci like staph aureus, strep (GAS, GBS, viridans), also some activity against gram negative bacilli (e.coli)
34
What can't cephalosporins treat?
Enterococci or listeria
35
Is cefazolin penicillinase resistant?
Yes!
36
Adverse reactions of cephalosporins
Hypersensitivity