Module 14 Flashcards
Know the difference between sterilization, disinfection, antisepsis, degerming, and sanitization.
Sterilization-kills all forms of life and destroys endospores and viruses
Commercial Sterilization-sufficient heat treatment to destroy endospores of C. botulinum in canned foods
Disinfection-destruction of vegetative pathogens
Antisepsis-disinfection on living tissue
Degerming-removal of microbes from a limited area
Sanitization-lowering the number of microbes
What factors influence bacterial cell death (if exposed to a disinfectant for example) ?
Number of microbes-more takes longer
Microbial characteristics-endospores, mycolic acid, porins
Environment-if presence of organic matter which inhibits chemicals; part of biofilm
Time of exposure
Normally, what do we target to kill bacteria?
Plasma membrane, proteins, nucleic acids
What is autoclaving? How does it kill bacteria? How do we get the temperature to 121oC? When would we use autoclaving? Why aren’t food products autoclaved?
Moist heat
Sterilization
121 at 15 psi for 15 min
Kill/destroy all microbes/endospores due to high temperature denaturing proteins/destroying membrane
Used for liquids and other items
Not used for food because it would denature the proteins and caramelize the sugars which would change the taste of the food product
New
How does autoclaving differ from pasteurization? What are the three types of pasteurization? When would we use pasteurization?
Pasteurization does not make anything sterile
Lower temp for a longer time (63 degrees for 30 min)
High temp for short time (72 degrees for 15 sec)
Ultra-high temp (140 degrees for 5 sec)
This is used for food products like milk
What are the three types of dry heat sterilization? When would each be used?
Flaming-1200 degrees (flaming a loop)
Incineration-1000 degrees (hospitals)
Hot air sterilization-170 degrees for 2 hours (glassware but no liquids)
What is filtration? When would you use filtration?
The physical removal of microbes
Used when a material can not have heat sterilization
How does low temperature inhibit cell growth?
Low temperature (0-7 degrees) are bacteriostatic which slows down bacterial growth but does not stop or kill~has no effect on psychotrophs
How does dessication inhibit cell growth? What type of cells will be most sensitive to drying? How does drying compare to osmotic pressure? What type of solution causes plasmolysis?
Without water, the metabolism shuts down growth
Most sensitive=Treponema and Neisseria gonorrhoeae
Not sensitive=Mycobacterium (has mycolic acid)
Osmotic pressure is based off of solute concentration, but both shut down cell growth
A hypertonic solution causes plasmolysis
What are the two types of radiation that are being used for sterilization? How do they differ from each other? When would you use each type?
Ionizing-Gamma or X-rays; high energy; damages DNA; could be used for meat but the public does not like the idea (no understanding)
Nonionizing-UV light; Damage DNA by thymine dimers; used for surface sterilization
What are the major differences between antibiotics and disinfectants?
Disinfectant
-Location- Extrenal only
-Target- Non specific in plasma membrane
-Concentration- 10 mg/ml, more
-Source- Organic chemist
-Simple structures
Antibiotics
-Location- external/internal
-Target- really specific, one site of activity
-Concentration- 10 ug/ml, less
-Source- microbes
-Complex structures
What is the similarity and difference between a disinfectant and an antiseptic? Be able to give an example of each.
Disinfectant- product that does destruction of vegetative pathogens on inanimate objects
-lysol
Antiseptic- product that does destruction of vegetativepathogens on living tissue
-listerine
How is disinfectant efficiency (activity) measured? Give two examples and describe/list steps of each.
Use-dilution test
-Take metal rings
-Rings into product- concentration going to sell at
-Rings into growth media
Filter paper method
-Similar to Kirby Bauer method
Why is phenol no longer used for surgery as it was when first introduced by Joseph Lister? What does phenol target to control microbial growth? Is phenol still used today? If so, in what would you look to find it?
Phenol is toxic
- Carcinogen
- Neurotoxin
- Irritant
Still used for surfaces, instruments, and skin surfaces
Targets plasma membrane
Common phenolic- O-phenylphenol
What are two types of bisphenols?
- Hexachlorophene-pHisoHex
- Triclosan- ingredient was in antibacterial soaps, toothpastes, cutting boards, ect
- Stops enzyme for fatty acid production
- FDA banned use in 2016 in most products
a. Bacteria started to evolve around-resistant
b. Affects human hormones
