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Flashcards in Antibiotics 1 Deck (22)
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1
Q

What is virulence?

A

the ability of a bacterial cell to invoke an infection

2
Q

What is antimicrobial pharmacodynamics?

A

the relationship of drug concentration to its anti-microbial effects

3
Q

What is antimicrobial pharmacokinetics?

A
  • drug absorption
  • distribution
  • elimination from the body
4
Q

When are oral drugs appropriate to treat the bacterial infection?

A
  • chosen for infections that are mild and can be treated on an outpatient basis
5
Q

When are IV drugs appropriate to treat a bacterial infection?

A
  • chosen for the most serious infections (vancomycin is poorly absorbed by the intestine)
6
Q

What patient factors must be taken into consideration when choosing an antibiotic?

A
  • immune system (if a patient has a weakened IS, we want to tx more aggressively)
  • renal function(can the kidney excrete it)
  • hepatic function(can the liver metabolize it)
  • poor perfusion (will it reach the target site)
  • age (elderly and young have weakened IS)
  • pregnancy/lactation
7
Q

What is empiric therapy?

A

choosing the antibiotic based on patient symptoms- only suspect that the bacterial infection is present, and we want to treat aggressively

8
Q

What is directed therapy?

A

when we know what the bacteria causing the infection is, we can pick an antibiotic that directly targets the bacteria

9
Q

When would you choose to use empiric therapy to treat an infection?

A
  • in the case of a polymicrobial infection (can pick a broad spectrum Ab)
  • severe headache, rigid neck, sensitivity to bright lights- suspect meningitis so we want to treat aggressively based on those symptoms
  • immunocompromised
  • low levels of neutrophils (neutropenia)
  • hospital infections (hospitals know what kind of infections are going around in the hospital- so practitioners will tx based on this)
  • age (want to treat young and old aggressively)
10
Q

What are 3 cases that we use antimicrobials for?

A
  1. prophylaxis - high risk so we want to dose them anyway
  2. Therapy - want to kill bacteria (most common)
  3. Suppression - do not want to kill all of the bacteria in the patients body, just want to suppress growth. Want to keep the infection localized and from becoming systemic
11
Q

What does bactericidal mean?

A
  • kills bacteria at concentrations achievable in the patient (bacterial number rapidly declines)
12
Q

What does bacteriostatic mean?

A
  • stops the growth and replication of organisms, limiting the spread of the infection (bacterial numbers plateau)
13
Q

What is seen with concentration dependent killing?

A
  • a significant increase in the rate of bacterial killing with higher concentrations of the drug
  • useful property for rapid killing of infective pathogens
14
Q

What is seen with time-dependent killing?

A
  • require time to achieve effective killing
  • higher concentration of the drug do not increase the rate of bacterial killing (increase in time, more bacteria is killed)
15
Q

What do narrow spectrum antimicrobial agents cover? What is an example of this?

A
  • act on a limited group of microorganisms

- isoniazid is an example- acts on mycobacteria

16
Q

What does extended spectrum antimicrobial agents cover? What is an example of this?

A
  • effective against 1 class of organisms as well as a significant number in a different class
  • an example of this is ampicillin
17
Q

What does broad spectrum antimicrobials cover? What is an example of this?

A
  • acts to kill a range of antimicrobial species

- tetracycline is an example, and can be used to treat a polymicrobial infection

18
Q

When would you use an antimicrobial combination?

A
  • for an unknown organism
  • a polymicrobial infection
  • antibiotic synergy
  • for certain patient/population factors
  • used when it is known in the hospital
  • also used in the case of dose related toxicity
19
Q

What are the disadvantages of antimicrobial combinations?

A
  • superinfections
  • eradication of normal microflora
  • resistance (MDR organisms)
  • adverse effects (greater toxicity)
  • patient adherence to therapy
  • increased cost
20
Q

What is synergism?

A

when the effect of 2 drugs in combination is greater than the sum of the effect when 2 drugs are administered independently

21
Q

What is antagonism?

A

when the effect of 2 drugs in combination is less than the sum of the effect when 2 drugs are administered independently

22
Q

Describe the mechanisms of synergy

A
  • one drug enhances uptake of the second
  • one drug enhances the metabolic effect of the other
  • drugs act sequentially in a common pathway
  • drugs inhibit the same target but in different ways
  • 2 or more drugs inhibit targets in different pathways