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48 Cards in this Set

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Define: Sterilization
Killing / removing all microorganisms including spores
Define: Disinfection
Killing of many, but not all microbes. Reducing the number of bacteria to low level that disease is unlikely to occur (used on inanimate objects).
Define: Sanitization
Reducing microbial contaminate to a safe level
Define: Asepsis
Absence of pathogenic microbes
Define: Sepsis
Presence of pathogenic microbes
Define: Antiseptic
chemicals applied to body surfaces to destroy or inhibit vegetative pathogens
Define: Antibiotics
Products of microbes which inhibit other microbes. Some of htem are safe enough to be taken orally / treat human infections
Define: Biocide
General term used for a chemical that has a broad spectrum activity
Define: Static
Chemical that inhibits multiplication but does not kill
Examples of Static:
Bacteriostatic, Fungistatic (reaction is reversible)
Define: Cidal
Kills microbes
Examples of Cidal:
Bacteriocidal, fungicidal, sporocidal (Not reversible)
Define: Microbial Death
Permenant Loss of reproductive capability, even under optimum growth conditions.
What is around a naked virus?
Protein Coat
What is around an enveloped virus?
What is more resistant to detergents (naked or enveloped?)
Naked is more resistant
What is the target of action (4 steps)
1. cell wall
2. cell membrane
3. protein/ nucleic acid synthesis
4. interfere with protein function (denature proteins)
3 ways to achieve killing or removing microbes?
1. Physical (heat, radiation)
2. Chemical (gases and liquids)
3. Mechanical (filteration)
What is more effective? Moist or Dry heat?
Moist Heat.
Three 3 ways that Moist Heat is used:
1. Boiling
2. Pasteurization
3. Tyndallization
Define: Boiling
Boil at atmospheric pressure (100C) at sea level.
Can kill vegetative cells in 10 min but not spores.
Not a means of sterilization
Define: Pasteurization
Aim to kill pathogenic bacteria in milk and some canned foods.
62C for 30 min, followed by rapid cooling (or flash method which is 72 C for 15 min and then rapid cooling).
Define: Tyndallization:
Intermittent boiling.
Can attain sterility
Define: Autoclaving:
Boil under pressure (15 pounds per square inch).
A pressure cooker (121 C, 20 min)
Kills all including spores
What does dry heat do to proteins?
Denatures proteins.
Dry Heat incineration includes 2 things:
Direct flaming and dry hot air.
Define: Direct flaming:
Used to sterilize heat resistant materials for immediate use.
Define: Dry hot air:
In dry oven
Head resistant materials like glassware can be sterilized by dry heat.
Which takes longer? Dry or moist heat?
Dry Heat takes longer.
What does cold do to microbes?
Retards microbal activities
refridgeration temerature/ deep freezing
Desiccation means to
reduce the amount of water
food preservation
How are microbes affected with desiccation?
Microbes differ in sensitivty to desiccation
Define: Lyophilization
Drying in a frozen state
Preserve microbes for many years
2 types of radiation used ?
Ionizaing Radiation
Non-Ionization radiation
Define: Ionizing Radiation:
x-rays, gamma, high speed electrons
use to sterilize head sensative materials (syringes, gloves)
Non-ionizing radiation:
UV light, causes mutation in DNA
Destroys DNA forming bonds
Most lethal (240-280nm)
poorly penetrates objects
Used to sterilize air, operation room, surfaces, treatment of drinking water.
Define: Sonication
Sound waves
high frequency sound beyond the sensitivity to the human hear
used in dental practices
Define: Filtration
- mechanical removal using filers
- sterilize heat sensitive liquids (like enzymes, solutions for Intravenus administration)
What are the most common bacterial filters?
Nitrocellulase membranes
(pore size 0.22nm)
Chemical agents are group according to their
Mode of Action
Disruption of Cell Membrane means....
dissolve phospholipid bilayer
(ie. alcohol as antiseptic)
Damage to DNA means...
DNA reactive chemicals are capable of forming bonds the bases in DNA.
(Many dyes etc).
What are agents that are active on the cell membrane?
Denaturing proteins takes place with which elements?
Flourine, Bromine, Chlorine, Iodine
Other denaturing proteins also take place in (which elements) :
Heavy Metals (silver nitrate)
(prevent eye infection in new born babies from gonoccal infections)
Hydrogenperoxide is:
antiseptic to clean wounds and contact lenses
Ethylene Oxide is
Gas used to sterilize heat sensative medical materials (gloves, syringes)
Chemicals with surface action are
detergents, soaps