Kirby Bauer Disk Diffusion Method

Introduction

• Presented by Dr. Rowe
• Important in microbiology labs and clinical settings

Method Overview

• Known as the Kirby Bauer disk diffusion method
• Used to assess the effectiveness of antimicrobials/antibiotics

Procedure

• Confluent Lawn:
  • Entire plate covered with microbes
  • Unlike streak or pour plates which spread bacteria out
  • Students use cotton tip applicators to coat the plate
  • In clinical settings, pathogens isolated from sick individuals are used
• Application of Discs:
  • Discs contain known quantities of antimicrobials/antibiotics
  • Incubate the plate to observe results

Zones of Inhibition

• Clear areas around the discs indicating no microbial growth
• Important to measure size accurately
• Significance of Size:
  • Must be compared to standardized data tables
  • Determines if the organism is sensitive, intermediate, or resistant

Standardization

• Uses special Mueller Hinton (MH) plates
• Thickness of Mueller Hinton agar matters

Interpretation

• Larger zones do not necessarily mean the antibiotic is the most effective
• Does not indicate if the antibiotic is bactericidal (kills microbes) or bacteriostatic (inhibits growth)

Educational and Practical Importance

• Effective tool for teaching antibiotic efficacy
• Example: Antibiotics work better against Staphylococcus aureus compared to Pseudomonas
• Common laboratory organisms: Staphylococcus aureus, E. coli, Pseudomonas, Proteus vulgaris

Conclusion

• A valuable method in both educational and clinical settings
• Highlights differences in antibiotic effectiveness

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• Note: This summary is based on Dr. Rowe's explanation of the Kirby Bauer disk diffusion method and its applications.