Evaluating Antibiotic Efficacy Through the Kirby-Bauer Assay

Patrick from GoldBio demonstrates a modified disk diffusion assay, known as the Kirby-Bauer assay, to test antibiotic efficacy. The video covers the preparation of materials, including bacterial cultures and antibiotic disks, and explains the process of plating and incubating the disks. The results are measured by observing the zone of inhibition, which indicates bacterial susceptibility. The video aims to help labs save money by testing the potency of stored antibiotics before purchasing new ones.

What is the primary purpose of the Kirby-Bauer assay?

• To measure the concentration of bacteria in a sample.

• To determine the pH level of a solution.

• To identify the type of bacteria present in a sample.

• To test the efficacy of antibiotics against bacteria.

Why is it important to use both sensitive and resistant bacterial cultures in the assay?

• To ensure the antibiotic is effective against all types of bacteria.

• To validate the accuracy of the zone of inhibition measurement.

• To compare the growth rates of different bacteria.

• To test the antibiotic's effect on bacterial DNA.

What is the final concentration of ampicillin solution needed for the test disks?

• 2.0 mg per ml

• 1.0 mg per ml

• 0.5 mg per ml

• 0.1 mg per ml

How much liquid can each test disk hold?

• 10 microliters

• 25 microliters

• 20 microliters

• 15 microliters

What is the purpose of labeling agar plates with sections?

• To track the drying time of the disks.

• To measure the temperature of the agar.

• To differentiate between different test disks after incubation.

• To identify the type of bacteria used.

Why is it important to sterilize tweezers between placing disks?

• To improve the accuracy of the zone measurement.

• To ensure the disks dry faster.

• To prevent contamination between disks.

• To maintain the temperature of the disks.

What should be included on each plate as a control?

• A disk with a different antibiotic.

• A disk with a lower concentration of antibiotic.

• A disk with no antibiotic and a purchased control disk.

• A disk with a higher concentration of antibiotic.

How long should the plates be incubated before measuring the zones of inhibition?

• 20 to 24 hours

• 16 to 20 hours

• 12 to 16 hours

• 8 to 12 hours

What indicates that the antibiotic product is working correctly?

• The test disks dissolve completely in the agar.

• The test disks show no zone of inhibition.

• The test disks match or exceed the standard zone of inhibition.

• The test disks have a smaller zone of inhibition than the control.

What can be concluded if the test disks exceed the standard zone of inhibition?

• The antibiotic is too concentrated.

• The antibiotic is working correctly.

• The antibiotic is ineffective.

• The bacteria are resistant.