Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharm Exam #3 > L27 - O'Keefe - Intro to Antibiotics Part 2 > Flashcards

L27 - O'Keefe - Intro to Antibiotics Part 2 Flashcards

1
Q

How does antibiotic selection differ for empiric vs directed/targeted therapy?

A

For directed therapy, since you know the organism and susceptibility, you can use a drug with a more narrow spectrum

*also, for directed therapy the antibiotic is given for a pre-defined duration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Compare the duration of therapy for the 2 causes of meningitis…

A

Meningitis due to strep pneumoniae = treat for 10-14 days

meningitis due to Niesseria meningitidis = 7 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are two types of therapies that can be employed for the use of antibiotics?

A

Prophylactic therapy and combination therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define prophylactic therapy

A

antibiotics are give to PREVENT the development of infection

choose therapy based on drug of choice for the most probably organism and susceptibility patterns of the region

administer as long as the patient is at risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define Combination therapy (specifically…what are 3 things it can be used to do?)

A
  1. broaden bacterial coverage to all organisms causing infection
  2. decrease the emergence of resistance
  3. take advantage of synergy by using more than 1 antibiotic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are two examples of prophylaxis (prevention) that were discussed in lecture?

A

peri-operative surgical prophylaxis

endocarditis prophylaxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain peri-operative surgical prophylaxis

A

wound infections can be caused by skin flora

during operations, antibiotics are given against skin flora to reduce wound infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

explain endocarditis prophylaxis

A

to prevent endocarditis, antibiotic is given against oral flora for dental procedures

applies if person has a damaged or prosthetic heart valve or previous endocarditis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

For both prophylaxis examples, what is the overall dosing regimen?

A

single dose given only

no benefit from prolonged antibiotic use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 possible effects from combination therapy?

A

synergy
additive
antagonism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define synergy

A

the antimicrobial effect of the two drugs together is greater than the additive activity of each one separately

(A + B) > A + B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define additive

A

the antimicrobial activity of the drugs used together is equal to the sum of each one separately

(A + B) = A + B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define antagonism

A

the antimicrobial activity of the drug combo is less than what you would expect from the addition of each one

(A + B)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give an example of synergy

A

For enterococcal endocarditis:

penicillins don’t kill enterococcus, but if you add gentomyacin (aminoglycoside) you get rapid killing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Compare and contrast bacteriostatic vs bactericidal (definitions)

A

Bacteriostatic = antibiotic INHIBITS bacterial growth, killing depends on host defense mechanisms (to “cure” the infection)

Bactericidal = antibiotic KILLS bacteria, is less dependent on host defense mechanisms

*note: he said to know whether classes are bacteriostatic or bactericidal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are disadvantages of bacteriostatic antibiotics?

A

If host defenses are inadequate, organisms that were only partially inhibited could survive/replicate and give a recurrent infection upon stopping use of the antibiotic (or if serum conc of the antibiotic go below the MIC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Give an example where host defenses won’t be sufficient to get ride of infection

A

Endocarditis = infection on a clot in a valve

because there’s no blood supply to the clot, host defenses don’t reach it

18
Q

What are examples of bacteriostatic antibiotics?

A

macrolides, ketolides, tetracyclines, glycylcylines, sulfonamides, clindamycin, Synercid, and linezolid

*note: he said to know whether classes are bacteriostatic or bactericidal

19
Q

When would you want to use a bactericidal antibiotic (overall)?

A

it’s preferable if the host immune system is compromised or doesn’t function well (ex: neutropenia or immunosuppresion)

*remember: neutropenia = low neutrophil levels

20
Q

Bactericidals are required for the treatment of…? (give 4 examples)

A

meningitis (host defenses aren’t effective in sub-arachnoid space)
endocarditis
osteomyelitis
febrile neutropenia

21
Q

What are examples of bactericidal antibiotics?

A

penicillins, cephalosporins, carbanpenems, aztreonam, fluoroquinolones, aminoglycosides, vancomycin, daptomycin, Bactrim, and metronidazole

*note: he said to know whether classes are bacteriostatic or bactericidal

22
Q

What is plotted for a pk graph? pd graph? pk/pd graph?

A

PK graph = conc vs time
PD graph = conc vs effect (aka dose response curve)
PK/PD graph = effect vs time

23
Q

What are two important PD parameters for antibiotics?

A

AUC/MIC

Time above MIC

24
Q

What is PAE?

A

Post-antibiotic effect

it’s the time it takes for the bacteria to re-grow once serum conc of antibiotic fall BELOW the MIC (is drug and organism specific!)

ex: sometimes the organism starts to grow immediately but sometimes there’s a gap (the gap is the PAE)

25
Q

What is the benefit of a long PAE?

A

You can safely spread the dose out and allow serum concentrations to fall below MIC

26
Q

Describe the PAE for gram positive bacteria

A

all antibiotics have some PAE

beta-lactams have a PAE of 2 hours

27
Q

Describe the PAE for gram negative bacteria

A

prolonged PAEs seen with: protein or nucleic acid synthesis inhibitors (ex: aminoglycosides or fluoroquinolones)

28
Q

Define concentration dependent killing

A

Get more rapid and extensive killing with higher serum concentrations…the higher the level of drug in serum, the more rapid the killing

Prolonged persistent effects (post-antibiotic)

29
Q

Give an example of concentration dependent killing

A

Once daily aminoglycosides

give a high “once a day” dose and avoid toxicity

30
Q

Define time dependent killing

A

killing depends on time of exposure above MIC (not higher serum concentrations)

seen with highly resistant organisms

31
Q

How would dosing differ for time dependent killing?

A

can extend dosing (ex: infuse for 4 hours instead of 1) so the drug stays in the patient for a longer period of time even if the peak level is lower

*you’re increasing exposure of patient to a concentration of drug that’s effective against the organism

32
Q

what is the general approach to the selection of an antimicrobial? (give 5 “steps”)

A
  1. confirm presence of infection
  2. select empiric therapy (start therapy before you know what the organism is)
  3. identify the pathogen
  4. modify/streamline the antibiotic therapy
  5. monitor therapeutic response
33
Q

What are the 3 infection-specific parameters to consider when choosing an antibiotic?

A
  1. severity of infection
  2. site of infection
  3. infecting organism

(ex: don’t give orally for sepsis)

34
Q

What are 6 host-specific factors to consider when choosing an antibiotic and why?

A
  1. allergies (and degree of cross-reactivity)
  2. age (elderly have dec renal function and thus maintain antibiotics for longer)
  3. pregnancy or nursing (potential effect on fetus and there’s also increased in Vd as well as renal clearance)
  4. rental and hepatic function
  5. concomitant drug therapy
  6. underlying disease states
35
Q

Why is renal/hepatic function important for choosing antibiotics?

A

Diminished function may lead to drug accumulation and undue toxicity so you have to adjust doses

36
Q

What antibiotics are primarily eliminated by the kidneys? (7)

A 
most beta-lactams
vancomycin
aminoglycosides
some fluoroquinolones
Bactrim
daptomycin
tetracycline
37
Q

What antibiotics are primarily eliminated/metabolized by the liver? (9)

A 
macrolides
Synercid
linezolid
clindamycin
metronidazole
some fluoroquinolones
Bactrim
doxycyline
tigecycline
38
Q

What is one example where you must consider concomitant drug therapy when choosing an antibiotic?

A

azoles for fungal infections inhibit the cyp system

ex: in the case of a kidney transplant, cyclosporins are given and azole would increase the levels of cyclosporins

39
Q

what disease states may predispose patients to infection/pathogens?

A

diabetes and soft tissue infections
burns and skin infections
trauma patients

40
Q

What are the 7 drug factors you must consider when choosing an antibiotic?

A
  1. in-vitro activity and current susceptibilities
  2. established clinical efficacy
  3. drug of choice charts
  4. PK and tissue penetration (MUST get sufficient concentrations at the site of infection)
  5. PD (type of bacterial activity needed for organism and infection type)
  6. side effect profiles
  7. cost
41
Q

Which is more costly…IV or oral antibiotics?

A

IV

42
Q

Monitoring serum concentrations and toxicity can be costly. This is done for which group of antibiotics?

A

Aminoglycosides

Pharm Exam #3 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions