[LAB] Exercise 8A: Kirby-Bauer Disk Diffusion Flashcards
Meaning of MIC
Minimum Inhibitory Concentration
Zones of inhibition can be interpreted using established break points recommended by what organization?
Clinical Laboratory Standards Institute (CLSI)
This method involves spreading bacteria on an agar plate and placing paper discs impregnated with antibiotics on the plate
Kirby-Bauer
Areas around the antibiotic disk where no bacterial growth can be seen
Zone of inhibition
This zone shows that an antibiotic has been successful in stopping bacterial growth
Zone of inhibition
What is measured in the zone of inhibition?
Diameter
Type of test tubes used
Sterile Loeffler test tube or Sterile screw cap tube
T or F: A vortex mixer is needed to perform Kirby-Bauer
T
Size of sterile Petri dish needed
100mm or 150mm
T or F: The test culture on BAP or TSA or NAP should be strictly 18-hour-old
F
should be less than 24-hour-old
Using an inoculating loop or needle, how many similar looking colonies should you fish out?
3-5
How many mL of NSS should be used in suspending fished out colonies?
5
The suspension is mixed for ___ seconds using a vortex.
15
T or F: If a vortex is not available, rub the sides of the tubes with an inoculating loop or needle to mix the colonies
T
The turbidity of the suspension is virtually compared to
0.5 McFarland Standard
T or F: Distilled water can be used to dilute the suspension to achieve the desired turbidity
T
T or F: More colonies can be added to the suspension to increase turbidity
T
T or F: In standardizing the inoculum, make sure that the test tubes are of the same size
T
What is the culture media used in performing Kirby-Bauer Method?
Mueller Hinton Agar (MHA)
The surface of the MHA medium is inoculated by what method of streaking?
Overlap method
How many times should you perform the overlap method of streaking?
2 to 3 times
In streaking, rotate the plate at ___ degrees each time to ensure an even distribution
60
T or F: The rim/edge of the medium is swabbed before streaking
F
after
The inoculation of the medium is done no more than ___ minutes from the time standardized inoculum was prepared
15
Place the inoculated plates on a flat level surface with the lid partially open for ____ minutes before applying antibiotic disks
3 to 5
This is used to place antibiotic disks on the agar surface
Flame-sterilized forceps
T or F: Press the disk using the tip of your gloved finger to make sure it has complete contact with the agar surface
F
using the tip of the forceps
Distance of each disk from one another
24 mm
Distance of each disk from the edge of the plate
10 mm
T or F: Plates are inverted when placed in the incubator
T
Set the incubator at ____ degrees Celsius for _____ hours
35 to 37; 16 to 18
Examine the plate after _____ hours of incubation
16 to 18
Used to measure the diameter of the zones of inhibition
Ruler or Vernier Caliper
T or F: MHA should have bacterial growth
T
Arrange the steps in order:
- Inoculation of MHA plate
- Application of antibiotic disks
- Reading and interpretation
- Preparation and standardization of test inoculum
4 > 1 > 2 > 3
