What is the Difference Between Agar Well and Disc Diffusion Method?
🆚 Go to Comparative Table 🆚The agar well diffusion and disc diffusion methods are both in vitro techniques used to evaluate antimicrobial activity. However, there are some differences between the two methods:
- Method of application: In the agar well diffusion method, a hole or well is created on the medium, and the extract solution is filled into it. In the disc diffusion method, a filter paper disc containing the test solution is placed on the agar surface.
- Sensitivity: The disc diffusion method is used to determine the general sensitivity of a particular concentration of an antibiotic, while the well dilution technique is used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the same antibiotic selected from the disc technique.
- Ease of performance: Both methods are simple and low-cost in vitro methods, but the disc diffusion method is considered easier to perform in clinical microbiology laboratories.
- Limitations: Neither method can distinguish between bactericidal and bacteriostatic effects, and both methods are not appropriate for determining the minimum inhibitory concentration.
In summary, while both the agar well diffusion and disc diffusion methods are useful for evaluating antimicrobial activity, the disc diffusion method is generally considered easier to perform and is used to determine the general sensitivity of an antibiotic. The agar well diffusion method, on the other hand, is used to determine the MIC and MBC of the same antibiotic.
Comparative Table: Agar Well vs Disc Diffusion Method
The agar well diffusion and disc diffusion methods are both used to evaluate antimicrobial activity. Here is a table comparing the two methods:
| Feature | Agar Well Diffusion Method | Disc Diffusion Method |
|---|---|---|
| Test Preparation | Extract solution is added to a hole (well) created in the agar medium | Filter paper disc containing the test solution is placed on the agar surface |
| Inoculation | Pathogenic bacterial species are inoculated on the agar plate using the spread plate technique | Same as agar well diffusion method |
| Antimicrobial Agent | Antimicrobial agent diffuses through the agar medium, inhibiting the growth of microorganisms | Similar to the well diffusion method, but with a disc instead of a well |
Both methods involve inoculating an agar plate with a pathogenic bacterial species and allowing the antimicrobial agent to diffuse through the agar medium to inhibit microbial growth. The key difference between the two methods is the way the test solution is applied to the agar plate: in the well diffusion method, it is added to a hole created in the agar, while in the disc diffusion method, it is applied to a filter paper disc placed on the agar surface.
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