Preparation[edit]
All aspects of the Kirby-Bauer procedure are standardized to ensure consistent and accurate results. Because of this, a laboratory must adhere to these standards. The media used in Kirby-Bauer testing must be Mueller-Hinton agar at only 4 mm deep, poured into either 100m or 150mm Petri dishes. The pH level of the agar must be between 7.2 and 7.4.
Inoculation is made with a broth culture diluted to match a 0.5 McFarland turbidity standard, which is roughly equivalent to 150 million cells per mL.
Incubation Procedure[edit]
1.Using an aseptic technique, place a sterile swab into the broth culture of a specific organism and then gently remove the excess liquid by gently pressing or rotating the swab against the inside of the tube.
2.Using the swab, streak the Mueller-Hinton agar plate to form a bacterial lawn. To obtain uniform growth, streak the plate with the swab in one direction, rotate the plate 90° and streak the plate again in that direction.
Repeat this rotation 3 times.
3.Allow the plate to dry for approximately 5 minutes.
4.Use an Antibiotic Disc Dispenser to dispense discs containing specific antibiotics onto the plate.
5.Using a flame-sterilized forceps, gently press each disc to the agar to ensure that the disc is attached to the agar.
6.Plates should be incubated overnight at an incubation temperature of 37 °C (98.6 °F).[3]