Which of the following lists the steps of the Kirby-Bauer method of antimicrobial sensitivity testing in the correct order?

• A. Inoculate agar plate with bacteria, place antibiotic disks, incubate plate, measure zones of inhibition
• B. Incubate plate, inoculate agar plate with bacteria, place antibiotic disks, measure zones of inhibition
• C. Measure zones of inhibition, incubate plate, inoculate agar plate with bacteria, place antibiotic disks
• D. Place antibiotic disks, inoculate agar plate with bacteria, measure zones of inhibition, incubate plate

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by inoculating the agar plate evenly with the bacterial culture. This ensures a uniform lawn of bacteria for testing the antibiotics.
2. Step 2: After the agar surface is inoculated, place the antibiotic-impregnated disks onto the surface of the agar. Each disk contains a different antibiotic to test sensitivity.
3. Step 3: Incubate the agar plate for a specified period, usually 16-24 hours, at an appropriate temperature to allow bacterial growth and antibiotic diffusion.
4. Step 4: After incubation, observe the plate and measure the zones of inhibition, which are clear areas around the antibiotic disks where bacterial growth has been prevented.
5. Step 5: Use the measured zone sizes to determine the sensitivity or resistance of the bacteria to each antibiotic, based on standardized charts.