Card Set Information
: Microbiocidal, Bactericidal, Fungicidal
A sterile object that is harboring microorganisms and viruses
Destruction or removal of
forms of microbial life, including endospores
Sufficient heat treatment to kill endospores of
Destruction of vegetative pathogens. (In lab)
Destruction of vegetative pathogens on
Treatment intended to
drinking utensils to safe public health levels
PHYSICAL METHODS OF CONTROL
Physical agents for controlling MOS growth are intended to achieve sterilization
Thermal Death Time (TDT) - the lenght time required to kill a bacterial population at a given temperature.
Thermal Death Point (TDP) - the minimum temperature required to kill a bacterial population at a given temperature.
Works by Oxidation
B. Dry Heat
Hot air oven
Radiating dry heat for sterilization
160 degrees C for 2 hours
will kill spores
Glassware, dry powders, etc.
Works by oxidation, but organics must be removed
C. Moist Heat
A. Boiling Water- moist heat penetrates faster than dry heat. Works by denaturing proteins, however, it does not kill many spores or many viruses. (will not sterilize)
B. Steam under pressure- autoclave. This is the most dependable method of sterilization.
Autoclave 121.5 degrees C for 15 minutes
mild heating, not sterilization
A mechanical method to remove microorganisms by passing a liquid or air through a filter
HEPA filter- removes 99% of all particles
OR, burn units, etc.
A. Ultravilet UV (radiant energy)
Works by 2 methods thymine to thymine producing the wrong protein code & by imparing the replication of the chromosome prior to binary fission
Will not work on spores.
F. Drying or Dessication
Works by disrupting metabolism
No water = no chemical organisms
Bacteriostatic- stops the growth
G. Osmotic Pressure
Plasmolysis- removal of water in a hypertonic solution
H. Low Temperature
Retards growth by lowering the metabolic rate of MOS
CHEMICAL METHODS OF CONTROL
Chemical agents rarely achieve sterilization. They destroy the pathogenic organism on or in an object.
Highly reactive releasing oxygen
Strong oxidizers which inactivate certain proteins and enzymes and may change cell membrane structure
Chlorine combines with water to form HYPOCHLOROUS ACID (*active ingredient)
Sodium hypochlorite- Clorox bleach
Drinking water, pools, etc
Effective against a broad spectrum of organisms including most G+ & G- organisms, many viruses, fungi, and protozoa.
Not sporicidal, not sterilization
More germicidal than chlorine
Tincture- a substance dissolved in ethyl alcohol, Antiseptic for wounds
Iodophor- a complex of iodine and detergents that is used as an antiseptic and disinfectant. An advantage of iodophors is the fact that it releases Iodine over a long period of time and doesn't stain
: Betadine, used in pre-operative skin prep.
B. Phenol (carbolic acid, phenolics & bisphenols)
Expensive & odoruous, & harsh to skin
Phenolics are phenol derivatives that have a germicidal activity and lower toxicity
Bisphenols- 2 molecules of phenol joined together. Lysol.
Triclosan-a bisphenol that disrupts cell membranes by blocking the synthesis of lipids. Found in kitchen sponges, utensils, & cutting boards
Disadvantage, possibility of bacterial species developing resistance to triclosan
Ethyl alcohol (ethanol) is the preferred alcohol
Works by protein denaturation & lipid dissolution
Bactericidal & fungicidal (on things that are not alive)
Not effective against endospores or non enveloped viruses
Mode of action is degerming
Coagulates cytoplasmic proteins forming a layer that microorganisms get under and grow, on skin not good.
C. Soaps & Detergents
Soap is a chemical compound of fatty acids combined with potassium or sodium hydroxide
The pH is around 8.0
Mode of action
: mechanical removal
Soaps are surface active agents called surfctants (degermer)
Emulsify & dissolve particles clinging to a surface & reduce surface tension
D. Hydrogen Peroxide- Peroxides
Hydrogen Peroxide reacts with catalase (enzyme in skin cells) to form oxygen &water
Not a good antiseptic but works on inanimate objects
reacts with catalase= water & oxygen, bubbles, oxygen being liberated.