Difference Between Agar Well and Disc Diffusion Method

The agar well diffusion method open a few holes on the agar and there are placed the substances that are going to diffuse while in the method of diffusion in disc on agar are placed discs impregnated with the antibiotic on the agar. In both methods inhibition halos will be observed.

1. What is agar well diffusion method?
2. What is the principle of the agar disc diffusion method?
3. What is the purpose of the disc diffusion method?
4. What is paper disc diffusion method?
5. How do you do agar diffusion test?
6. What are the limitations of the disk diffusion assay?
7. What is special about Mueller Hinton agar?
8. What does the Zone of Inhibition tell you?
9. What does the size of the zone of inhibition tell you?
10. How do you do antibacterial activity?
11. Why is the disc diffusion technique not a perfect indication?
12. What does it mean if there is no zone of inhibition?

What is agar well diffusion method?

Agar well diffusion method is widely used to evaluate the antimicrobial activity of plants or microbial extracts [32], [33]. Similarly to the procedure used in disk-diffusion method, the agar plate surface is inoculated by spreading a volume of the microbial inoculum over the entire agar surface.

What is the principle of the agar disc diffusion method?

This method is based on the principle that antibiotic-impregnated disk, placed on agar previously inoculated with the test bacterium, pick-up moisture and the antibiotic diffuse radially outward through the agar medium producing an antibiotic concentration gradient.

What is the purpose of the disc diffusion method?

Disc diffusion in agar is a common method of testing the sensitivity of bacteria to antibiotics. A microorganism is judged sensitive or resistant according to the diameter of the zone of inhibition of cultural growth, which is then correlated statistically with the minimal inhibitory concentration (MIC).

What is paper disc diffusion method?

The method consists of placing paper disks saturated with antimicrobial agents on a lawn of bacteria seeded on the surface of an agar medium, incubating the plate overnight, and measuring the presence or absence of a zone of inhibition around the disks (Figure 1). ...

How do you do agar diffusion test?

In this method, the test agar plate is swabbed with a standardized concentration of the test organism, and then paper disks containing a defined antibiotic concentration are placed on the lawn of bacteria. After overnight incubation, the diameter of the zone of inhibited growth around the disk is measured.

What are the limitations of the disk diffusion assay?

There are serious limitations to the use of disk diffusion method. Results may be unexpected or borderline. In such cases another method of testing may be required or the test may need to be repeated for confirmation.

What is special about Mueller Hinton agar?

Mueller-Hinton has a few properties that make it excellent for antibiotic use. ... Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. Second, it is a loose agar. This allows for better diffusion of the antibiotics than most other plates.

What does the Zone of Inhibition tell you?

The Zone of inhibition is a circular area around the spot of the antibiotic in which the bacteria colonies do not grow. The zone of inhibition can be used to measure the susceptibility of the bacteria to wards the antibiotic.

What does the size of the zone of inhibition tell you?

If the observed zone of inhibition is greater than or equal to the size of the standard zone, the microorganism is considered to be sensitive to the antibiotic. Conversely, if the observed zone of inhibition is smaller than the standard size, the microorganism is considered to be resistant.

How do you do antibacterial activity?

Among these methods, the most common are listed below.

1. Agar well diffusion method. Agar well diffusion method is widely used to evaluate the antimicrobial activity of plants or microbial extracts [32], [33]. ...
2. Agar plug diffusion method. ...
3. Cross streak method. ...
4. Poisoned food method.

Why is the disc diffusion technique not a perfect indication?

Why is the disk-diffusion technique not a perfect indication of how the drug will perform in vivo? ... Variables such as serum, body pH, ionic content, oxygen level and how a drug is metabolized and excreted and side effects of the drug.

What does it mean if there is no zone of inhibition?

A lack of visual zone does not mean the antimicrobial agent is ineffective: the zone of inhibition test requires the antimicrobial agent to migrate into the nutrient agar. If the antimicrobial is not compatible with the nutrient agar, it will not migrate to create a visual zone of inhibition.