Podcast
Questions and Answers
What is the difference between a microbicidal effect and a microbistatic effect?
What is the difference between a microbicidal effect and a microbistatic effect?
Which statement correctly describes antiseptics?
Which statement correctly describes antiseptics?
What is the purpose of the Disc-Agar Diffusion Technique mentioned in the text?
What is the purpose of the Disc-Agar Diffusion Technique mentioned in the text?
What should students bring for the activity, according to the text?
What should students bring for the activity, according to the text?
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What do disinfectants do?
What do disinfectants do?
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In what contexts are antiseptics typically used?
In what contexts are antiseptics typically used?
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What should be done after transferring the filter paper discs onto the plated media?
What should be done after transferring the filter paper discs onto the plated media?
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Which category of agents is specifically used to control microorganisms on nonliving materials?
Which category of agents is specifically used to control microorganisms on nonliving materials?
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Which statement about antibiotics is true?
Which statement about antibiotics is true?
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What is the role of sterile forceps in the Disc-Agar Diffusion Technique?
What is the role of sterile forceps in the Disc-Agar Diffusion Technique?
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Which step involves documenting after incubation in the Disc-Agar Diffusion Technique?
Which step involves documenting after incubation in the Disc-Agar Diffusion Technique?
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How are zones of growth inhibition identified after incubation in the Disc-Agar Diffusion Technique?
How are zones of growth inhibition identified after incubation in the Disc-Agar Diffusion Technique?
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Study Notes
Control of Microorganisms
- Control of microorganisms is essential in various fields to prevent and treat diseases, and to inhibit the spoilage of foods and other industrial products.
- Common methods of control involve chemical and physical agents that affect microbial structures and functions.
Microbicidal and Microbistatic Effects
- Microbicidal effects kill microbes immediately.
- Microbistatic effects inhibit the reproductive capacities of cells and maintain the microbial population at a constant size.
Antiseptics, Disinfectants, and Antibiotics
- Antiseptics are chemical substances used on living tissue to kill or inhibit the growth of vegetative microbial forms.
- Disinfectants are chemical substances that kill or inhibit the growth of vegetative microbial forms on nonliving materials.
- Antibiotics are synthesized and secreted by some true bacteria, actinomycetes, and fungi that destroy or inhibit the growth of other microorganisms.
Objectives of the Activity
- Perform the disc-agar diffusion technique for testing antimicrobial activity of common agents.
- Demonstrate the effects of common antiseptics and disinfectants on the growth of Gram-positive and Gram-negative bacteria.
- Evaluate the inhibitory effects of certain antibiotics on the growth of bacteria.
Disc-Agar Diffusion Technique
- Obtain three sterile plated media (Mueller-Hinton agar) and inoculate each with the test microorganism using the two swab techniques.
- Soak the filter paper discs into the chemicals to be tested for antimicrobial effects.
- Transfer the discs on the plated media with the use of sterile forceps.
- Incubate for 24 hours at 24 ºC.
- Measure zones of growth inhibition after incubation with the use of a ruler.
- Calculate the microbial index as follows: Microbial index (MI) =
- Document the plates after incubation.
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Description
Explore the effects of antibiotics, antiseptics, and disinfectants in controlling microorganisms. Learn about the importance of these chemicals in preventing and treating diseases, as well as inhibiting spoilage of food and industrial products.
