Questions and Answers
Which microbial forms has the highest resistance to physical and chemical controls?
bacterial endospores
The process that destroys or removes all microorganisms and microbial forms, including bacterial endospores, on inanimate objects is?
sterilization
The use of a physical or chemical process to destroy vegetative pathogens on inanimate objects is?
disinfection
The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is?
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Scrubbing or immersing the skin in chemicals to reduce the numbers of microbes on the skin is?
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Which type of control agents would be used to achieve sterility?
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The easiest microbial forms to kill or inhibit are?
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The method of removing vegetative microbial life forms and debris to reduce contamination to safe levels is termed?
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The method of removing vegetative life forms from living surfaces is termed?
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The removal of all life forms from inanimate objects is termed?
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The alcohol wipe used on a patient's skin before an injection is an example of?
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Which is correct regarding the rate of microbial death? A. Cells die at increasingly greater rates. B. Only older cells die in a culture. C. Cells in a culture die at a constant rate. D. Upon contact with the control agent, all cells die at one time. E. Cells become metabolically inactive but are never killed.
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Which of the following factors will influence the action of microbial agents? A. The number of microorganisms B. The type of microorganisms present C. Temperature and pH D. Mode and dosage of the agent E. All of the choices will influence the action.
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Microbial death occurs when there is?
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A target of antimicrobial agents except?
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Surfactants work by?
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Some microbial control agents are able to _____ cell proteins by breaking bonds that maintain the native state, the three-dimensional configuration of the proteins.
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Agents that can denature microbial proteins include all of the following except?
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Which of the following does not affect microbial nucleic acids?
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Physical agents for controlling microbial growth include all of the following except? A. Ultraviolet radiation. B. Boiling water. C. HEPA filters. D. Pasteurization. E. Hydrogen peroxide.
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Sterilization is achieved by? A. Flash pasteurization. B. Hot water. C. Boiling water. D. Steam autoclave. E. All of the choices are correct.
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Dry heat?
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The minimum sterilizing conditions in a steam autoclave are?
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The shortest time required to kill or inactivate all the microbes in a sample at a specified temperature is called the?
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The lowest temperature needed to kill or inactivate all microbes in 10 minutes is the?
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Disinfection of beverages such as apple juice, milk, and wine is optimally achieved by?
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Placing organisms at 4°C is?
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Pasteurization?
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_____ heat is more rapidly effective and efficient compared to _____ heat.
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A method for sterilizing milk, called _____ treatment, uses 134°C for 1 to 2 seconds.
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What instrument is most effective for pressure-temperature sterilization?
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Study Notes
Microbial Resistance and Control Methods
- Bacterial endospores exhibit the highest resistance to physical and chemical controls.
- Sterilization is the complete destruction or removal of all microorganisms, including bacterial endospores, from inanimate objects.
- Disinfection refers to using physical or chemical processes to destroy vegetative pathogens on inanimate surfaces.
Antimicrobial Techniques
- Antisepsis involves using chemical agents on exposed body surfaces to destroy or inhibit vegetative pathogens.
- Degermation consists of scrubbing or immersing skin in chemicals to reduce microbial numbers.
- Sporicides are control agents specifically designed to achieve sterility.
Microbial Forms and Their Susceptibility
- Vegetative bacteria and fungi are the easiest microbial forms to kill or inhibit.
- Sanitization is the process of removing vegetative life forms and debris to reduce contamination to safe levels.
- Antisepsis also applies to removing vegetative life from living surfaces.
Microbial Death and Influencing Factors
- Microbial death is indicated by the cessation of reproduction.
- Cells in a culture die at a constant rate upon exposure to control agents.
- Multiple factors influence the action of microbial agents including the number and type of microorganisms, temperature, pH, mode, and dosage of the agent.
Actions of Antimicrobial Agents
- Surfactants work by disrupting membrane integrity.
- Some antimicrobial agents can denature cell proteins, altering their three-dimensional configuration.
- X rays do not denature microbial proteins nor do they affect microbial nucleic acids.
Physical Control Methods
- Physical agents for controlling microbial growth include ultraviolet radiation, boiling water, HEPA filters, and pasteurization, but not hydrogen peroxide.
- Steam autoclave is the most efficient sterilization method, requiring at least 121°C at 15 psi for 15 minutes.
- Dry heat is less efficient than moist heat for microbial control.
Heat and Microbial Inactivation
- Thermal death time (TDT) is the shortest time needed to kill all microbes at a specified temperature.
- Thermal death point (TDP) is the lowest temperature required to kill all microbes in 10 minutes.
- Pasteurization effectively reduces the number of vegetative forms in beverages like milk and juice.
Temperature and Microbial Growth
- Storing microorganisms at 4°C demonstrates bacteriostatic properties.
- Moist heat is more effective and efficient than dry heat in controlling microbial growth.
- Ultra high temperature (UHT) treatment sterilizes milk using 134°C for 1-2 seconds.
Sterilization Tools and Techniques
- The autoclave is the most effective instrument for pressure-temperature sterilization.
- Intermittent sterilization involves a process spread over 3 days with low temperatures.
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