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Microbiology: Antimicrobial Agents and Microbial Control

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  • What is sterilization?

    Sterilization is the process of destroying all forms of microbial life, including spores, on a surface or in a substance.

  • Define disinfection.

    Disinfection is the process of eliminating or reducing harmful microorganisms from inanimate objects, but it may not kill spores.

  • What is degerming?

    Degerming is the mechanical removal of microbes from a limited area, such as skin around an injection site.

  • Explain sanitization.

    Sanitization reduces microbial numbers on eating utensils or surfaces to safe public health levels.

  • What is pasteurization and its original purpose?

    Pasteurization is a mild heat treatment to reduce pathogens and spoilage organisms, originally to make milk safe for consumption.

  • Difference between -static and -cidal treatments?

    -static agents inhibit microbial growth, while -cidal agents kill microbes.

  • Common targets of antimicrobial agents?

    Targets include the cell wall, cell membrane, proteins, and nucleic acids.

  • Potential dangers of antimicrobial agents to humans?

    Some agents can damage human cells by affecting similar structures or cause allergic reactions or toxicity.

  • How do environmental conditions affect antimicrobial effectiveness?

    Factors like temperature, pH, and presence of organic matter can increase or decrease antimicrobial activity.

  • How does time influence antimicrobial agent effectiveness?

    Longer exposure generally increases microbial kill rates and effectiveness of the agent.

  • What are bio-safety levels (BSL)?

    BSLs are classifications of lab safety practices from 1 to 4, increasing with the risk of the microbes handled.

  • When is moist heat in an autoclave preferred over dry heat?

    Moist heat (autoclave) is preferred for sterilizing heat-resistant materials quickly; dry heat is used for materials damaged by moisture.

  • Applications of pasteurization today?

    Used to reduce pathogens in milk, juices, and other beverages while preserving flavor and nutrients.

  • Limitations of refrigeration in microbial control?

    Refrigeration slows growth but does not kill microbes; some psychrophiles can grow at low temperatures.

  • Limitations of filtration in microbial control?

    Filters remove microbes physically but cannot remove viruses or toxins effectively.

  • Name major categories of antimicrobial chemicals.

    Includes alcohols, aldehydes, phenolics, halogens, oxidizing agents, surfactants, heavy metals, gases, and enzymes.

  • Role of enzyme agents in prion removal?

    Enzymes can degrade prions on medical instruments, which are resistant to standard sterilization.

  • Methods to measure disinfectant effectiveness?

    Includes phenol coefficient, use-dilution test, disk-diffusion method, and in-use test.

  • How do organisms use fermentation to produce alcohol?

    Microbes metabolize sugars anaerobically, producing alcohol as a byproduct of fermentation.

  • Impact of oxygen on bacterial growth?

    Oxygen can be essential, toxic, or neutral depending on bacterial type (aerobes, anaerobes, facultative anaerobes).