Lecture 21: Antimicrobial Susceptibility Testing Flashcards Preview

First Semester: Principles of Infectious Disease > Lecture 21: Antimicrobial Susceptibility Testing > Flashcards

Flashcards in Lecture 21: Antimicrobial Susceptibility Testing Deck (16)
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1
Q

Two tests that use dilution methods

A
  • Broth dilution test (quant)

- Agar dilution test (quant)

2
Q

Agar diffusion methods

A
  • Disk/tablet test (semi-quant)

- Gradient diffusion E-test (quant)

3
Q

Diffusion methods enable quantification of antimicrobial susceptibility by determining:

A
  • Minimum inhibitory concentration

- Minimum bactericidal concentration

4
Q

MIC

A

The lowest concentration that inhibits complete growth of the test strain

5
Q

MBC

A

Lowest concentration that kills the test strain

6
Q

Is serial dilution susceptibility testing MIC/MBC accurate?

A

Nope, because it reflects a range

7
Q

Two types of broth dilution

A

Macro and micro dilution

8
Q

Microdilution enables

A

automated or semiautomated reading

9
Q

Agar dilution is primarily used for

A

Research purposes

Ex. When many strains have to be tested with one drug

10
Q

Breakpoint

A

A drug-specific value to interpret the results of susceptibility testing and determine if an antibacterial is potentially useful in the treatment of a bacterial infection

11
Q

A strain is defined as susceptible by

A

A level of antimicrobial activity associated with a high likelihood of therapeutic success

12
Q

A strain is defined as resistant by

A

A level of antimicrobial activity associated with a high likelihood of therapeutic failure

13
Q

Mixed cultures are frequent with

A

otitis externa, wound infections, and UTI’s

14
Q

Surrogate antimicrobials are used when?

A

In the lack of approved clinical breakpoints to predict susceptibility to other drugs belonging to the same class

15
Q

Two drugs used to ID MRSA/MRSP

A
  • Oxacillin

- Cefotoxin

16
Q

Strains that are resistant to oxacillin/cefotoxin should be regarded as resistant to

A

All beta lactams irrespective of their susceptibility to penicillins and cephalosporins