AST pt. 3

Question 1

Measures amount of antimicrobial agent in serum or body fluid

Answer 1

Antimicrobial Concentration Test

Question 2

Measure lowest concentration of antimicrobial agent that kills a bacterial isolate

Answer 2

Minimum Bactericidal Concentration (MBC)

Question 3

Measure the highest dilution or titer of a patient’s serum that is inhibitory to the bacterium and the highest dilution or titer that is bactericidal
* Predictive of response to current antibiotic regimen

Answer 3

Serum Bactericidal Test (Schlichter Test)

Question 4

Measures susceptibility to a combination of antimicrobial agents

Answer 4

Synergy

Question 5

Measure the rate of killing of bacteria by measuring the number of remaining viable bacteria

Answer 5

Time Kill Assay

Question 6

Tests that Monitor Effectiveness of Therapy

Answer 6

• Molecular Detection (detection of resistance genes)
• MBC
• Serum Bactericidal Titers
• Antimicrobial Levels
• Concentration of antibiotic in serum just before the antibiotic is given (trough level), and 15-20 mins after the dose is administered (peak level)
  *Peak Level – therapeutic indicator
• Trough Level – Toxicity indicator
• Antibiotic Synergy Test

Question 7

– therapeutic indicator

Answer 7

 Peak Level

Question 8

Toxicity indicator

Answer 8

Trough Level

Question 9

• Reference Method: Agar Dilution Method
• Recommended Agar: Supplemented Brucella, laked sheep blood agar

Answer 9

Anaerobes (SUSCEPTIBILITY TESTING)

Question 10

QUALITY CONTROL

Answer 10

• Use of standard reference strains that are susceptible to antimicrobial agents
• QC strains should represent varying degrees of susceptibility or resistance
• CLSI has identified ATCC (American Type Culture Collection) strains to be used for QC
• QC procedures must be done daily or weekly if there is acceptable performance with the QC strains
• Use of antibiograms

Question 11

• This is for mass spectrometry
• Can be used for accurate and rapid identification of various microorganisms, such as Gram-positive bacteria, ___, ____, ____, ____, ___

Answer 11

MALDI-TOF, Gram-positive bacteria, Enterobacteriaceae, nonfermenting bacteria, anaerobes, and even mycobacteria and yeasts

Question 12

• Allows analysis of multiple isolates and use biochemical reactions
• More efficient that manual methods

Answer 12

Automated Methods

Question 13

Principle employed in automated methods

Answer 13

Photometry (Colorimetry)
Nephelometry
Fluorometry

Question 14

• Use of Plastic Tray with Substrates in multiple wells
  For ID and AST
• Computer Software and Module

Answer 14

Semiautomated Systems

Question 15

• Redox Indicator System to measure bacterial growth

Answer 15

BD Phoenix

Question 16

AM: BD Phoenix
Redox Indicator System to measure bacterial growth
* Nephelomtery: ?

Answer 16

Microscan Walkaway SI
Use of hydrated microdilution panels
Standard Dried Panels
Detection of bacterial growth (color change)

Question 17

TREK Sensitire

Answer 17

• Fluorometric detection system
  VITEK System
• Use of plastic reagent cards that contain microliter quantities of anitmicrobial agents
• Kinetic measurement of growth