30 Questions
What method is used to sterilize inoculating loops and needles?
Direct Flaming
What is the purpose of pasteurization?
To prevent the spoilage of beverages
What is the minimum temperature required for hot air sterilization?
170oC
What is the difference between dry heat and moist heat?
Dry heat transfers heat less effectively to a cool body, than moist heat
What is the purpose of incineration?
To sterilize disposable items and biological waste
What is the minimum time required for hot air sterilization?
2 hours
What are the two main categories of methods used to control microbial growth?
Physical methods and Chemical methods
What is the pattern of microbial death when bacterial populations are heated or treated with antimicrobial chemicals?
A constant percentage of the extant population is killed each minute.
What are the ideal characteristics of a sterilization/disinfection process?
Highly efficacious, Fast, Good penetrability, Compatible with all materials, Non-toxic, Effective despite presence of organic material, Difficult to make significant mistakes in process, Easily monitored
What is an example of a physical method used to sterilize materials?
Dry heat or Moist heat
What is the purpose of inoculating wires and loops with red heat?
To sterilize them
What are the two methods of pasteurization mentioned in the text?
The two methods are Classic Method and High Temperature Short Time Pasteurization (HTST).
What is an example of a chemical method used to disinfect surfaces?
Alcohols
What is the purpose of using a fan in dry-heat sterilization?
To obtain uniform temperature by circulation.
What is the temperature and duration required for HTST pasteurization?
72°C for 15 seconds.
What is the purpose of Inspissation in sterilization?
To sterilize serum or egg media.
How does dry heat kill microorganisms?
By denaturation of bacterial proteins, oxidative damage, and toxic effect of elevated levels of electrolytes.
What are the factors that influence the effectiveness of heat in sterilization?
The factors are nature of heat, temperature and duration, characteristic of organism and spores, and type of material.
What is the temperature and duration of steam used in Tyndallisation?
100°C for 20 minutes on three successive days
What is the advantage of using steam above 100°C in an autoclave?
It has a better killing power than dry heat and bacteria are more susceptible to moist heat.
What are the components of an autoclave?
A vertical or horizontal cylinder, lid with screw clamps, asbestos washer, discharge tap, pressure gauge, and safety valve.
What are the standard sterilization conditions in an autoclave?
121°C, 15 lb per square inch, and 15 minutes holding time.
What is the purpose of the discharge tap in an autoclave?
To release air and steam.
Why are instruments packed for sterilization?
To be stored and handled without being contaminated.
What pore size is required for filtration if viruses must also be removed?
around 20 nm
How must filtration equipment and filters be sterilized?
by autoclaving at a temperature that does not damage the fragile filter membranes
Why are prions not removed by filtration?
Not specified in the text, but prions are notoriously difficult to remove or inactivate.
What type of air filtration is used in pharmaceutical sterile filtration?
HEPA (High Efficiency Particulate Air) filtration
What additional method is often used in conjunction with HEPA filtration to kill trapped bacteria and viruses?
high-energy ultraviolet light units
What is the purpose of testing the filtration system?
to ensure that the membranes have not been punctured prior to or during use
Learn about the ideal sterilization and disinfection process, its characteristics, and the rate of microbial death. Understand the importance of sterilization and disinfection in controlling microbial growth.
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