Control of Microorganisms: Physical and Chemical Methods
formaldehyde
%) is used to inactivate viruses and toxins used in vaccines, it also destroys spores inbacteria and fungi.
Formaldehyde
* 8% *Reacts with NH₂, SH and COOH groups *Disinfectant, kills endospores
Ethylene oxide
* other agents for sterilization * is effective by carcinogenic (potential to cause cancer) and explosive gas
Chlorine
*****deoxides*** Forms hypochlorous acid (HClO), a strong oxidizing agent *Disinfect drinking water however one disadvantage is that it binds to organic matter and become inactive
Isopropanol
*50-70% *Denatures proteins and solubilizes lipids *Antiseptic used on skin
Dry heat (hot air oven)
*Good for glassware, metal, not plastic or rubber items
Boiling
*Moist heat *Denaturation *Kills vegetative cells but not spores *Equipment,dishes
Chemical Control important terms
Antiseptics are used to destroy pathogens on living tissue. • Sepsis refers to contamination by microorganisms. • Sanitizing means reducing microbial population to a safe level. • De-germing means removing organisms from an object's surface.
Autoclaving
Moist heat and pressure it Denaturation of portions Good method of Sterilization
qualities of a good disinfectant
No Damage to surface or person but penetratable and useful in all situations (heat/cold) and dissolvable in water and easy to obtain and has no odor.
uv light includeing x rays and gamma rays are used in what type of sterlization
This is only used for surface sterilization because it denatures proteins and dries cells cytoplasm. Dna absorbs ultraviolet radition and cause thymine dimmers who distort the dna and cause errors in them.
phenols
damage cell membranes and inactivate enzymes of microorganisms, while denaturing their proteins
ethyl alcohol used to
disinfect delicate instruments by killing bacteria and found in bactericides
Biguanides
disrupt plasma and effective at killing bacteria and fungi and used to contromicrobial growth on the skin and mucous membrane. It is the active ingredient in many surgical hand scrubs and is used to clean the skin of surgical patients before surgery.
Alcohol how is it disinfects/antiseptic
disrupts membranes by causing lipid dissolution denature proteins. they have solvent action on lipids and those in the plasma membrane
Ethylene oxide
disrupts proteins and can achieve complete sterilization in 4 hours and its has good penetration and can sterlize large items and kills endospores
Incineration over an naked flame
dry heat and it oxidizes many microbiol components
Halogen are
iodine bromine and fluorine are elements that are electronegative. They have the ability to oxidize molecules stealing electrons and disrupting cellular components
Disinfection
is killing of spores and viruses and is often achieved by the use of chemicals called disinfectants. It is used for inanimate objects
What does iodine disinfects
is used to disinfect wound, water, and resturant equipment
Autoclave and pressure cooker (steam under pressure)
kills all forms of life including bacterial endospores. *The substance being sterilized must be maintained at the effective Temp for the full time
Aldehydes
other agents for sterilization and causes cross-linking that inactivates proteins and nucleic acids
Idophores how is it disinfects/antiseptic
release iodine over a long period of time and disrupts protein function
Isopropyl alcohol is used in
rubbing alcohol
why are idophores used rather than Iodine
stains and causes allergic reaction
alcohol is not effective against
they are not effective against enveloped viruses or bacterial endospores. They effectively destroy bacteria and fungi by disrupting the lipids in the plasma membrane resulting in lysis, and denatures proteins.
Cold Boiling
ultrasonic device with container of cold solution to vibrate any form of life
Physical Methods of Control
• Heat is one of the most common physical control methods. uv light and pasteurization scrubbing and cold boiling are other types of physcial methods
Distinct properties of Antiseptics and Disinfectants
• They should be: • To kill/slow growth of microbes • Nontoxic to humans and animals • Soluble in water. • Storable. • Effective quickly •Even in low concentration. • Also important in choosing an agent are: • Temperature. • pH. • Duration of disinfection.
Pasteurization
A heating process that REDUCES the number of spoilage germs and eliminates pathogens in milk and other heat sensitive foods
Flash pasteurization or high temp short time pasteurization
A type of pasteuriation, using moist heat to reduce bacterial population, where the liquid is heated at 71.6 degrees C for 15 seconds.
Chlorine does what, where
Keeps bacterial population low in municipal water supplies and swimming
Sterilization
Kills or removes all forms of life, including bacterial endospores. it is which is commonly achieved by using heat combined with pressure and is more complete then disinfection
Germicide/Biocid
A chemical agent that demonstrates killing power against various microbes
types of alcohol are
Ethanol and isopropanol are widely used as skin antiseptics,
QUATS
Quaternary Ammonium Compounds: disinfectant that are considered nontoxic, odorless, and fast acting and are a good surface cleaner
Antisepsis
Refers to the killing or removal of microbes on living tissues
Dry and moist heat are applied differently
The dry heat changes microbial proteins and removes water, slowly burning the microbes. Moist heat (like boiling water) is faster and effective at a lower temperature thandry heat. It kills microbes by denaturing their proteins. Boiling water may not kill all spores or inactivate all viruses.
Sanitization
Usually used by the food industry. Reduces microbes on eating utensils to safe, acceptable levels for public health
X rays and gamma rays does what to microbes
X rays and gamma rays (ionizing radiations) force electrons out of microbial molecules. This affects cell metabolism and physiology
Gas sterilization is used for
a wide variety of hospital equipment especially those made of plastics that would be destroyed by heat
factors of disinfectant the killer provided more convincing tales
are time of exposure kind of organism ph of disinfectant materials nature concentration of disinfectant temperature of disinfectant
Phenols are not good for antiseptic use why?
are two toxic to the skin for antiseptic use so are used on feces and surfaces. They are however stable compound and are active in organic compounds. Poor against endospores, good at mycobacteria.
surface disinfection can use
biguanides and alcohol and isophone and QUATS
what two methods use moist heat
boiling and autoclave (both denature proteins) it is more effective then dry heat because water is heat is easier transferable between substances however does not kill spores