Clinical Use of Abx

Question 1

Describe why endocarditis is considered to be in a protected local environment. Tx?

Answer 1

fibrin/platelet mixture protects from host defense mechs; bactericidal therapy

Question 2

Describe why intracellular infections are considered to be in a protected local environment. Tx?

Answer 2

some bugs thrive intracellularly; need to penetrate these cells eg rifampin, tetracycline, erythromycin

Question 2

What is a consideration for drugs and the bladder? What drugs should be used?

Answer 2

• some drugs concentrate there, changing susceptibility - quinolones as a group are good EXCEPT moxifloxacin

Question 3

What does susceptible (S) mean?

Answer 3

bacteria will probably respond to the Abx

Question 3

Describe why abscesses are considered to be in a protected local environment. Tx?

Answer 3

drugs can’t penetrate; need surgical drainage

Question 4

Name 3 susceptibility tests.

Answer 4

1. broth dilution 2. disk diffusion (Kirby-Bauer) 3. E test

Question 5

What is the MBC?

Answer 5

the lowest conc of the Abx that kills 99.9% of the initial inoculum

Question 5

_____ Abx have MBC concentrations many fold higher than the MIC concentration.

Answer 5

Bacteriostatic

Question 7

What is the MIC?

Answer 7

the lowest concentration of Abx that prevents visible bacterial growth

Question 7

Bacteriostatic Abx have MBC concentrations ____ than the MIC concentration.

Answer 7

many fold higher

Question 8

Describe why meningitis is in a protected local environment. Tx?

Answer 8

within the BBB and protected from host defense mechs; bactericidal therapy

Question 9

What does resistance (R) mean?

Answer 9

infection will probably not respond to the Abx

Question 10

What is the E test?

Answer 10

strip containing a gradient of Abx is plated with a bug- clearing makes ellipse shape- where ellipse point meets the strip is the MIC

Question 11

At ____, the Abx should have a maximal serum conc that exceeds the MIC of the bacteria (Cp>MIC).

Answer 11

normal doses

Question 13

What is the MBC used to determine?

Answer 13

bactericidal vs bacteriostatic

Question 14

Bacteriostatic Abx have _____ many fold higher than the MIC concentration.

Answer 14

MBC concentrations

Question 15

What is broth dilution?

Answer 15

serial dilutions of Abx in liquid medium that are inoculated with standard #s of bugs- incubated- check growth- look at lowest conc of Abx that prevented growth (MIC)

Question 16

What does MIC stand for?

Answer 16

minimum inhibitory concentration

Question 17

Describe why foreign bodies are considered to be in a protected local environment. Tx?

Answer 17

they impair host defense mechs and promote attachment/biofilms; remove the foreign body

Question 18

What does MBC stand for?

Answer 18

minimum bactericidal concentration

Question 19

At normal doses, the Abx should have a _____ that exceeds the MIC of the bacteria.

Answer 19

maximal serum conc

Question 19

How should a chemo pt’s bacterial infection be treated and why?

Answer 19

with bactericidals bc they have decreased neutrophils

Question 21

What does intermediate (I) mean?

Answer 21

indeterminate or uncertain response given standard dosing

Question 22

Describe why bone infections are considered to be in a protected local environment. Tx?

Answer 22

protected from opsonophagocytosis; prolonged therapy with drugs that concentrate in bone eg fluoroquinolones

Question 24

When would you use empiric therapy?

Answer 24

1. life threatening infections 2. outpatient tx

Question 25

What local factor considerations should be made before giving an Abx to a pt?

Answer 25

1. distribution 2. protected local environments 3. the bladder 4. daptomycin and pulmonary surfactant

Question 27

Bactericidal Abx have _____ that are equal to or barely higher than the MIC.

Answer 27

MBC concentrations

Question 28

What is the relationship btw daptomycin and S. pneumoniae?

Answer 28

does not treat well bc it's inactivated by pulmonary surfactant

Question 29

At normal doses, the Abx should have a maximal serum conc that exceeds the ____ of the bacteria.

Answer 29

MIC

Question 30

What is an antibiogram?

Answer 30

a yearly summary of local susceptibility patterns for common pathogens

Question 31

\_\_\_\_\_ Abx have MBC concentrations that are equal to or barely higher than the MIC.

Answer 31

Bactericidal

Question 32

What does Susceptible-dose dependent (SDD) mean?

Answer 32

susceptibility depends on dosing regimen (need higher drug exposure)

Question 33

Bactericidal Abx have MBC concentrations that are ______ than the MIC.

Answer 33

equal to or barely higher

Question 34

What is the disk diffusion/Kirby-0Bauer test?

Answer 34

suspension of bug is plated and Abx disks placed on top- look for diameter of clearing around the disk

Question 35

What 7 host factors need to be considered when giving a drug to a pt?

Answer 35

1. hx of reactions to Abx 2. renal/liver function 3. age (fetus/neonates/young children) 4. genetic/metabolic factors (G6PD, diabetes) 5. pregnancy 6. drug interactions 7. immune status

Question 36

What is empiric therapy?

Answer 36

initiation of therapy before a specific diagnosis is made