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.
Want to see more full solutions like this?
Chapter 25 Solutions
Laboratory Experiments in Microbiology (12th Edition) (What's New in Microbiology)
- What are intrinsically disordered proteins, and how might they be useful for a living system?arrow_forwardWhat are Amyloid Fibrils? What biological functions are these known to perform?arrow_forwardHow do histamine and prostaglandins help in the mobilization of leukocytes to an injury site? What are chemotactic factors? How do they affect inflammation process?arrow_forward
- Compare and contrast neutrophils and macrophages. Describe two ways they are different and two ways they are similar.arrow_forwardDescribe the effects of three cytokines (not involved in the initial inflammation response). What cells release them?arrow_forwardDescribe activation of helper T cells or cytotoxic T cellsarrow_forward
- Compare and contrast MHC 1 and MHC 2. Describe two way they are different and two ways they similar including how they are used in antigen presentation.arrow_forwardDescribe two antimicrobial properties of the skin.arrow_forwardDescribe how the inflammation response starts including the sentinel cells and the chemicals involved. How do pathogens trigger the response particularly in the skin?arrow_forward
- How does complement promote the immune response? Describe three waysarrow_forwardWhich of the following is not a possible mechanism for autoimmunity? Select one: A. Abnormal expression of MHC II molecules in non-antigen-presenting cells B. Activation of polyclonal B cells C. Polymorphism of HLA alleles D. Molecular mimicry E. Release of sequestered antigensarrow_forwardWRITTEN WORK 3: NON-MENDELIAN GENETICS Part A: Complete the Punnett square and calculate for the probability of genotype and phenotype. i i Genotype: Phenotype: 08:55arrow_forward