Therapy for Staph and Strep I

Question 1

Concentration dependent

Answer 1

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

Question 2

Concentration dependent drug examples

Answer 2

Lipopeptides (daptomycin), aminoglycosides, fluoroquinolones

Question 3

Time dependent

Answer 3

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

Question 4

Time dependent drug examples

Answer 4

Beta-lactams, glycopeptides (vancomycin)

Question 5

MIC

Answer 5

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

Question 6

Broth Macrodilution

Answer 6

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

Question 7

E Test

Answer 7

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

Question 8

Bacteriostatic drugs and example

Answer 8

Arrest bacterial growth (linezolid)

Question 9

Bactericidal drugs and example

Answer 9

Kills bacteria (beta lactams, etc).

Question 10

Is vancomycin bacteriostatic or bactericidal?

Answer 10

It depends on the organism!

Question 11

Beta Lactam Antibiotics

Answer 11

Penicillins: Amoxicillin, Ampicillin, Nafcillin, Penicillin

Cefalosporins: Cefazolin (first generation)

Question 12

How do beta lactams work?

Answer 12

Bind to PBPs and inhibit transpeptidases.

Question 13

What is the best orally absorbed penicillin?

Answer 13

Amoxicillin

Question 14

How are penicillins eliminated?

Answer 14

Renally, with the exception of nafcillin.

Question 15

Natural penicillin is drug of choice for…

Answer 15

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

Question 16

Penicillin G vs Penicillin V

Answer 16

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

Question 17

Problem with natural penicillin?

Answer 17

Susceptible to penicillinases especially in Staph aureus.

Question 18

Anti-staphylococcal penicillin

Answer 18

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

Question 19

Does nafcillin work on gram negative organisms?

Answer 19

No.

Question 20

What organisms does natural penicillin work on?

Answer 20

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

Question 21

Extended Spectrum Penicillins (amino-penicillins)

Answer 21

Ampicillin and amoxicillin (both oral).

Question 22

What are amino-penicillins the drug of choice for?

Answer 22

Listeria monocytogenes

Question 23

What organisms do amino-penicillins work on?

Answer 23

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

Question 24

What must organisms have to be affected by beta lactams?

Answer 24

Peptidoglycan wall (mycoplasma is inherently resistant)

Question 25

How is MRSA so drug resistant?

Answer 25

It has an altered PBP that has lower affinity for all beta lactams except ceftaroline.

Question 26

Betalactamase inhibitors

Answer 26

Clavulanic acid, Sulbactam, tazobactam. Abundant in STAPH AUREUS

Question 27

Betalactamase inhibitors combined with beta lactams

Answer 27

Clavulonic acid and amoxicillin = augmentin
Sulbactam and ampicillin

These have increased gram negative activity.

Question 28

Penicillin hypersensitivity

Answer 28

Penicilloic acid can cause IgE mediated hypersensitivity

Question 29

Penicillin rash common in patients with…

Answer 29

EBV

Question 30

Penicillin diarrhea caused by

Answer 30

alterations in the commensal flora of the GI tract. C diff can overgrow

Question 31

Why isn’t methicillin used clinically?

Answer 31

Because it can cause nephritis

Question 32

Cephalosporins

Answer 32

5 generations. Higher generations have increased gram negativity and higher Vd.

Question 33

Cefazolin used for

Answer 33

Gram positive cocci like staph aureus, strep (GAS, GBS, viridans), also some activity against gram negative bacilli (e.coli)

Question 34

What can’t cephalosporins treat?

Answer 34

Enterococci or listeria

Question 35

Is cefazolin penicillinase resistant?

Answer 35

Yes!

Question 36

Adverse reactions of cephalosporins

Answer 36

Hypersensitivity