Is the disk-diffusion technique measuring bacteriostatic or bactericidal activity? Briefly explain.
To write:
The nature of the activity of the disc-diffusion technique.
Introduction:
The disc-diffusion method is also called Kirby-Bauer test. It is a technique that tests the effectiveness of the antibiotics on a specific microorganism. An agar plate is spread with bacteria and then, paper discs of antibiotics are added to it. The bacteria are allowed to grow on the agar media and inhibition zones are observed.
Explanation of Solution
Antibiotics eliminate the bacteria completely. They are categorized as bactericidal, that is potent and bacteriostatic, which hampers growth. Bactericidal antibiotics kill the bacteria directly while the bacteriostatic antibiotics inhibit the bacteria from growing. The disc-diffusion technique works both by inhibiting the growth as well as by killing the bacteria.
The zone of inhibition is formed around the antibiotic discs. Bigger is the area, maximum will be the activity of the antibiotic. Similarly, lesser is the area, the minimum will be the activity of the antibiotic. Around the antibiotic discs, bacteria are not grown in any case nor the bacteria have been killed. They kill the bacteria as well as inhibit the growth also. They act both ways of the action.
Thus, disc-diffusion technique measured both the ways of bactericidal as well as bacteriostatic activity as they inhibit bacterial growth and killed the bacteria as well.
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Chapter 25 Solutions
Symbiosis, Lab Experiments in Microbiology
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