Disk Assay Testing
Disk Assay Testing, often referred to as the Disk Diffusion Method or Kirby-Bauer Test, is a widely used microbiological technique to evaluate the antimicrobial susceptibility of bacteria. It helps determine which antibiotics are effective against a specific bacterial strain, guiding appropriate treatment decisions and supporting antimicrobial stewardship.
How It Works
- Preparation: A standardized bacterial suspension is spread evenly across the surface of a Mueller-Hinton agar plate to create a uniform lawn of growth.
- Application of Disks: Paper disks impregnated with known concentrations of antibiotics are placed on the agar surface.
- Incubation: The plate is incubated at 35–37°C for 16–24 hours.
- Interpretation: After incubation, clear zones (zones of inhibition) appear around disks where bacterial growth has been suppressed. The diameter of these zones is measured and compared to standardized charts (e.g., CLSI or EUCAST) to classify the bacteria as Susceptible (S), Intermediate (I), or Resistant (R) to each antibiotic.
Applications
- Clinical diagnostics: Identifying effective antibiotics for treating infections.
- Pharmaceutical R&D: Screening new compounds for antibacterial activity.
- Food safety and veterinary medicine: Monitoring antibiotic resistance in zoonotic pathogens.
- Environmental microbiology: Assessing resistance patterns in environmental isolates.
Advantages
- Simple and cost-effective
- Standardized and reproducible
- Visual and easy to interpret
- Adaptable for a wide range of bacteria and antibiotics
Limitations
- Not suitable for slow-growing or fastidious organisms
- Cannot distinguish between bacteriostatic and bactericidal effects
- Less precise than MIC (Minimum Inhibitory Concentration) methods for borderline cases
Leading food testing laboratory ensuring safety and quality in the food industry.
Contact Us
9341 E.Childs Ave., Planada, CA 95365, USA.
operations@fsa-lab.com
info@fsa-lab.com
support@fsa-lab.com
Office 1 : (209) 877 8728 Office 2 : (209) 877 8729