U2.1.2 Experiment 8-9 Flashcards
T/F Once agent has been identified & deemed as clinically significant, proper selection of antimicrobial agents is performed.
T
Provide MIC (minimum inhibitory concentration) values or zones of inhibition established using cut-off points/break off
Kirby-Bauer Disk Method
AST : Kirby-Bauer Disk Method
Spreading of bacteria on an agar plate and placing paper discs impregnated with antibiotics on the plate
Disk Diffusion
AST : Kirby-Bauer Disk Method
Area around antibiotic disk where no bacterial growth can be seen
Zone of Inhibition
AST : Kirby-Bauer Disk Method
What does the zones indicate
antibiotic is successful in stopping bacterial growth or killing bacteria
AST : Kirby-Bauer Disk Method
Diameter is measured to
compare efficacy of antibiotics and monitor antimicrobial resistance
AST : Kirby-Bauer Disk Method
Specimen
< 24 hour-old test culture on BAP, TSA or NAP
AST : Kirby-Bauer Disk Method
Turbidity of suspension of Inoculum is compared to
0.5 McFarland standard
AST : Kirby-Bauer Disk Method
Desired Turbidity of Inoculum
same turbidity with McFarland Standard
AST : Kirby-Bauer Disk Method
Turbidity of Inoculum is adjusted by
Adjust by adding sufficient sterile saline or adding more colonies
AST : Kirby-Bauer Disk Method
Inoculation of MHA Plate
Manner of streaking
inoculated by overlap method of streaking
AST : Kirby-Bauer Disk Method
Inoculation of MHA Plate
Rotate plate ____ each time for even distribution
60°
AST : Kirby-Bauer Disk Method
Inoculation of MHA Plate
Number of times plate is rotated
3-4x to ensure that it’s confluent
AST : Kirby-Bauer Disk Method
Inoculation of MHA Plate
Incoulation is done [time] from time of standard inoculum was prepared
done <15 minutes from time of
standard inoculum was prepared
AST : Kirby-Bauer Disk Method
Application of Antibiotic Disks
At least ____ from each other
At least ____ from edge of the plate
At least 24mm from each other
At least 10mm from edge of the plate
AST : Kirby-Bauer Disk Method
inverted and placed in incubator set at ___ for ____ hrs
set at 35- 37C for 16-18 hours
AST
uses standardized amount of test inoculum present in Mueller Hinton Broth (MHB) and a selected antimicrobial agent
Broth Dilution
AST : Broth Macrodilution
Medium used
Mueller Hinton Broth (MHB)
AST : Broth Macrodilution
Antimicrobial agent is diluted _____ fold
two fold
AST : Broth Macrodilution
lowest concentration of antimicrobial agent that completely inhibits visible growth
MIC
AST : Broth Macrodilution
Interpretative categories
Susceptible (S)
Intermediate (I)
Resistant (R)
Two categories of Broth Macrodilution
Broth microdilution & Broth macrodilution
Two categories of Broth Macrodilution
Main difference
volume of the MHB used
AST : Broth Macrodilution
Specimen used
Culture on BAP
AST : Broth Macrodilution
Adjusted inoculum diluted _____
diluted 1:200
AST : Broth Macrodilution
Final bacterial concentration
5x10^5 CFU/mL