CH13

• Explain BSL-1, and an example of it.

  BSL-1 poses minimal risk to hosts and doesn't cause disease. An example includes nonpathogenic strains of E. coli.
• Explain BSL-2, and an example of it

  BSL-2 poses moderate risk to hosts and is associated with diseases but typically isn't severe. An example includes S. aureus.
• Explain BSL-3, and an example of it


  BSL-3 poses serious or lethal respiratory diseases. An example is mycobacterium tuberculosis.
• Explain BSL-4, and an example of it.

  BSL-4 is extremely dangerous, and isn't a part of normal flora. Is considered exotic. An example is the ebola virus.
• What is sterilization?

  The destruction or removal of living microbes.
• What is sanitization?

  The reduction or inhibition of microbial contamination.
• What is disinfection?

  It is the killing of pathogenic microbes, typically by chemical means.
• disinfection: antiseptic

  The killing of pathogenic microbes on living objects.
• disinfection: disinfectant


  The killing of pathogenic microbes on inanimate objects.
• Disinfection can be virucidal, bacteriostatic, fungicidal, and bacteriocidal.
• What is the thermal death time?

  It is the time required to kill ALL organisms at a given temperature.
• What is the thermal death point?

  It is the minimum temperature at which organisms die at a given time.
• What is decimal reduction time?

  The time required at a specific temperature to kill 90% of organisms.
• Why is decimal reduction time useful in the food industry?

  It helps calculate the amount of time needed to kill specific pathogens.
• A rapid sterilization method used is direct flaming.
• Why is incineration a good sterilization method?

  It is highly effective at sterilizing reusable heat-tolerant objects and disposal objects.
• At what setting is the hot-air oven set at for sterilization?

  160 degrees Celsius for 2 hours.
• What is the hot-air oven used for?

  It is used to kill bacterial spores, causing loss of water and organic matter that could be used as heat protection.
• Why isn't boiling water considered a sterilization method?

  Bacterial/fungal spores, protozoal cysts, and certain viruses can't be assured of death through this method.
• Boiling water involves moist heat, which aids in protein denaturation and disrupting life processes.
• At what setting is the autoclave for sterilization?

  A pressure of $15 lbs/in^2$, 121.5 degrees Celsius for 15 minutes
• In the autoclave method, how are moist heat and pressure used?

  The moist heat is the sterilizing agent while the pressure allows superheating of steam.
• What are some limits of the autoclave?

  It can melt some plastics, can make sharp objects dull, and cannot effectively sterilize oily substances.
• What is pasteurization used for?

  It is used for reducing microbial growth in hopes of killing pathogenic bacteria. It is present in milk and wine.
• At what setting is pasteurization used?

  63 degrees Celsius for 30 minutes.
• At what setting is flash pasteurization used for killing pathogens?

  71.6 degrees Celsius for 15 seconds.
• At what setting is ultra-high temperature used for sterilization?

  140 degrees Celsius for 3 seconds.
• When is filtration used?

  It's used when heat isn't appropriate for the situation, such as when dealing with heat-sensitive liquids, blood solutions, or pharmaceuticals.
• How is filtration used?

  It used high-efficiency particulate filters, which remove 99% of particulates with a diameter larger than 0.3 microns.
• At what setting is ultraviolet used?

  265 nm
• How does ultraviolet light sterilize microbes?

  It causes adjacent thymine bases to link together to dimerize in DNA.
• What are some limitations of ultraviolet light?

  It cannot pass through glass, solids, or liquids. It can also cause skin cancer.
• How do x-rays and gamma rays sterilize?

  Their high energy creates ions, which can disrupt life processes.
• How do microwaves sterilize?

  They use their long wave radiation along with water to create friction.
• Who was the person who founded phenol as a disinfectant in hoshospitalsptials and surgical instruments?

  Joseph Lister
• What is the Phenol Coefficient?

  It is the value to describe effectiveness relative to phenol.
• What are the four chemical agent properties?

  1: The ability to slow/kill the growth of microbes

  2: To be nontoxic to humans and animals, especially as an antiseptic

  3: The ability to be soluble in water and have a substantial shelf life

  4: To be useful in dilute form
• How do halogens oxidize proteins?

  They inactivate necessary enzymes, leading to death within 30 minutes. This is because of their 7 electrons in their outer shell.
• Halogens: Chlorine as Hypochlorite

  Also known as bleach, is used to disinfect drinking water.
• Halogens: Chlorine as Chloramines

  Can kill bacteria, fungi, viruses, and protozoa. Can NOT kill spores.