Chemotherapy and antibiotic resistance Flashcards Preview

Block 6 Week 4 > Chemotherapy and antibiotic resistance > Flashcards

Flashcards in Chemotherapy and antibiotic resistance Deck (221)
Loading flashcards...
1

What is this:
chemical substances produced by various species of microorganisms that are capable of inhibiting, in small amounts, the growth of other microorganisms.

Antibiotics

2

What is an ideal antimicrobial?

-selective toxicity
-bactericidal rather than bacteriostatic
-absence of genetic or phenotypic resistance
-broad vs. narrow spectrum
-non-allergenic
-minimal adverse side effects
-remains active in body
-water soluble
-bactericidal levels can be reached in vivo

3

What are the sites of antibiotic action?

cell wall synthesis
membrane function or synthesis
nucleic acid synthesis
protein synthesis
metabolic pathways

4

What is the mechanism of resistance for antibiotics?

-enzymatic inactivation
-decreased permeability
-efflux
-modification of susceptible molecular target
-fail to convert an inactive precursor to its active form

5

How d you get modification of susceptible molecular target?

-Alteration of antibiotic binding site
-Protection of target site
-Overproduction of target
-Binding-up of antibiotic

6

What are the three components to pharmokinetics?

absorption
distribution
elimination

7

What is pharmacodynamics?

relationship between concentration and pharmacologic or toxi effects
relationship between concentrations and antimicrobial effect

8

When you are looking at concentration versus time in tissue and other body fluids-> what next do you look for?

pharmacologic or toxicological effect

9

When you are lookinat at concentration versus time at site of infection-> what next do you look for?

antimicrobial effect versus time

10

To be effective, an antibiotic needs to do what?

get to the microbe!

11

What are some issues associated with getting the antibiotic to the microbe?

absorption from the site of administration
transfer from plasma to site of infection
elimination from plasma
elimination from site of infection

12

What are the parameters of antimicrobial activity?

minimum inhibitory concentration (MIC)
Minimum bactericical concentration (MBC)
Bactericidal
Bacteriostatic
Synergy

13

What is bactericidal?
Give me some examples of these

kills microbe
beta lactams, vancomycin, fluoroquinolones, metronidazole, aminoglycosides

14

What is bacteriostatic?
Give me some examples of these

inhibit but do not kill the organism, relys on host to clear microbe
ex. tetracycline, clindamycin, macrolides, sulfonamides

15

What is synergy?
Give me an example.

a combination of antibiotics produces a 2-log 10 increase in action relative to each agent alone
Penicilin + gentamycin for treatment of viridans streptococcal meningitis

16

What is the postantibiotic effect?

persistent suppression of growth following exposure to an antimicrobial

17

What is the mechanism behind the postantibiotic effect (PAE)?

slows growth at sub-MIC concentrations
alters morphology

18

What is postantiobiotic leukocyte enhancement (PALE)?

increases susceptibility to phagocytosis
increases susceptibility to phagocytic killing

19

What is Time > MIC and when do you use it?

How long a drug stays above the MIC. Displays TIme-dependent killing. For drugs with minimal to moderate persistent effects

20

What is AUC/MIC and when do you use it?

Ratio of the 24-hour serum concentration curve to MIC.
Show total exposure of micobe to antimicrobial agent. For drugs with prolonged persistent effects.

21

What is Cmax/MIC?

Maximum serum cencentration/ MIC.
Shows concentration- dependent killings. For drugs with prolonged persistent effects.

22

In concentration dependent killing agents, what are the pharmacodynamic predictors of outcome and what drugs are the most effective?

higher drug concentrations have higher rate and extent of bactericidal activity
Cmax/MIC and AUC/MIC are pharmacodynamic predictors of outcome.

23

What are some examples of concentration-dependent kiling agents?

aminoglycosides, fluroquinolones, metronidazole

24

In time-dependent (concentration-independent) killing agents, what is the bactericidal action like? When does saturation of killing occur? What is the pharmacodynamic predictor of outcome?

relatively slow
saturation of killing occurs at low multiples of the MIC
T> MIC is pharmacodynamic predictor of outcome

25

What are some examples of Time-dependent (concentration-independent) kiling agents?

Beta lactams, vancomyocin

26

Why kind of post antibiotic effects (PAE) does bacteriostatic agents cause? what is the pharmacdynamic predictor of outcome for bacteriostatic agents?

prolonged
AUC/MIC

27

What are some examples of bacteriostatic agents?

tetracyclines, clindamycin, macrolides, sulfonamides

28

What group of antibiotics inhibit cell wall synthesis?

beta lactam antibiotics

29

What beta lactam antibiotics inhibit cell wall synthesis?

natural penicillins
penicillin derivatives
(penicillinase resistant, broad spectrum)
cephalosporins
carbapenems
beta lactamase inhibitors

30

What is the spectrum of natural penicillins?

narrow, mostly gram positive