Lecture 10 2/22/24

Question 1

How does an antibiotic differ from an antimicrobial?

Answer 1

-antibiotics specifically target bacteria
-antimicrobials are a broader class that act on microbes in general

Question 2

What is minimum inhibitory concentration?

Answer 2

lowest drug concentration that inhibits bacterial growth

Question 3

What is minimum bactericidal concentration?

Answer 3

lowest drug concentration that kills 99.9% of bacteria

Question 4

Which datapoints are used to determine pharmacological breakpoints?

Answer 4

-pharmacokinetic data
-pharmacodynamic data
-clinical outcomes
-epidemiologic data

Question 5

Who determines pharmacological breakpoints?

Answer 5

Clinical and Laboratory Standards Institute

Question 6

Which critically important antimicrobials are highest priority?

Answer 6

-quinolones
-3rd gen. + cephalosporins
-macrolides/ketolides
-glycopeptides
-polymyxins

Question 7

Which high priority critically important antimicrobials are commonly used in vet med?

Answer 7

-quinolones
-cephalosporins
-macrolides

Question 8

What are the main clinical signs of infection?

Answer 8

-pyrexia/fever
-leukocytosis
-inflammation
-neutropenic fever

Question 9

What evidence suggests infection?

Answer 9

-direct microscopic examination
-cytology
-gram staining

Question 10

Which infections will not require use of antibiotics?

Answer 10

-certain chronic infections
-abscesses
-cases with economic constraints

Question 11

In which situations should you address underlying factors instead of treating with antibiotics?

Answer 11

-situations that favor infection relapse
-group settings that contribute to spread of infection

Question 12

What are the consequences of prescribing antibiotics just in case?

Answer 12

-add to cost
-diarrhea/vomiting
-adverse reactions
-drug interactions
-select for bacterial resistance

Question 13

What factors should be considered when selecting an antibiotic?

Answer 13

-causative organism
-physiologic status of the patient
-cost/route/frequency of administration

Question 14

Why is it important to understand the nuances of the infection site?

Answer 14

-clues on organism involved
-clues on drug disposition features required
-clues on local host factors

Question 15

Why is it important to gram stain?

Answer 15

there are important pathophysiology and endotoxin differences between gram pos. and gram neg.

Question 16

Why is it important that gram neg. bacteria have an LPS outer layer?

Answer 16

LPS creates challenges for antimicrobial efficiency

Question 17

When is empirical therapy used?

Answer 17

-organism and susceptibility pattern can be reasonably estimated
-life-threatening infections

Question 18

When is objective therapy used?

Answer 18

when culture and susceptibility data is available

Question 19

What is a breakpoint?

Answer 19

-specific MIC of a drug selected to predict a clinical outcome
-for a specific pathogen, disease, species, and regimen

Question 20

What are the interpretations of MIC?

Answer 20

-susceptible
-intermediate
-resistant

Question 21

Which standardized tests can be used to determine MIC/breakpoints?

Answer 21

-disk diffusion
-E-test
-broth dilution

Question 22

What is important to consider regarding culture/susceptibility testing and actual use of antimicrobials?

Answer 22

-breakpoints are variably correlated with clinical efficacy
-penetration in target tissue may impact efficacy

Question 23

What percent of time must be spent above MIC for a time-dependent antimicrobial treating a gram pos. bacteria?

Answer 23

50% of dosing interval must be above MIC

Question 24

What percent of time must be spent above MIC for a time-dependent antimicrobial treating a gram neg. bacteria?

Answer 24

100% of dosing interval must be above MIC

Question 25

What concentration must a concentration-dependent antimicrobial reach in order to be effective?

Answer 25

8-10x MIC once

Question 26

What must be considered when deciding on dose?

Answer 26

-whether or not the label dose is still appropriate
-antibiotic PD profile
-infection location

Question 27

What is the SPACED acronym?

Answer 27

-spectrum
-PK/PD
-adverse reactions
-compliance
-environment
-diagnostics