246+-+MCRO2124+-+Lab+Midterm+Study+Sheet+PLUS

Exercise 8: Kirby-Bauer TestProcedure:

• Day 1: Create a uniform lawn of bacteria on an agar plate and place antibiotic disks on the surface.

• Day 2: Incubate the plate to allow bacterial growth and antibiotic interaction.

• Day 3: Measure the zones of inhibition around each antibiotic disk.

Zones of Inhibition:The zone of inhibition is the area around an antibiotic disk where bacteria cannot grow, indicating that the antibiotic is effective against the bacteria tested.

• Measurement: The diameter of the zone of inhibition is measured in millimeters.

• Interpretation:

  • A larger zone of inhibition suggests greater sensitivity of the bacteria to the antibiotic, whereas a smaller zone indicates more resistance.

  • Zones can be categorized as susceptible, intermediate, or resistant based on standard interpretive criteria established by the Clinical and Laboratory Standards Institute (CLSI).

• Clinical Relevance:Determining the effectiveness of antibiotics through the Kirby-Bauer test is critical in clinical settings for guiding appropriate antibiotic therapy and combating antibiotic resistance. This test allows healthcare providers to select the most suitable antibiotic treatment based on the specific pathogens involved in infections.