sterilization and disinfection Flashcards
Destruction and removal of all forms of microbial life, including endospores
sterilization
Usually done by steam under pressure or a sterilizing gas such as ethylene oxide.
sterilization
Sufficient heat treatment to kill endospores of Clostridium botulinum in canned foods.
More resistant endospores of thermophilic bavteria may survive, but they will not
germinate and grow under normal storage condition.
commercial sterilization
endospore of ___ in canned good
clostridium botulinum
Destruction of vegetative pathogens.
May make use of physical or chemical methods
disinfection
Destruction of vegetative state pathogens on living tissues.
Treatment is always by chemical antimicrobials.
antisepsis
Removal of microbes from a limited area such as the skin around the injection site.
Mostly a mechanical removal by an alcohol-soaked swab.
degerming
Treatment intended to lower microbial counts on eating and drinking utensils to
safe public health levels.
Maybe done with a high temperature washing or by dipping into a chemical
disinfectant.
sanitation
Bacterial population die at a constant rate when heated or treated with
antimicrobial agents.
rate of microbial growth
Factors affecting the effectiveness of
antimicrobial treatments:
The number of microbes
Environmental influences
Time of exposure
Microbial characteristics
kills microorganism primarily by coagulation of proteins
(denaturation), which caused by breakage of the hydrogen bonds that hold the
protein.
moist heat
kills vegetative bacterial and fungal pathogens and
almost all viruses within 10 minutes, less effective on endospores.
Boiling or flowing steam
preferred use of Boiling or flowing steam
Dishes, basins, pitchers, various equipments
mechanism of action of boiling or flowing steam
Protein denaturation
very effective method of sterilization, at about 15 psi
(121 degC), all vegetative cells and their endospores are killed in about 15
mins.
autoclaving
autoclaving is used in
Microbiological media, solutions, linens, utensils, dressings,
equipment, and other items that can withstand temperature and pressure.
mechanism of action in autoclaving
protein denaturation
the use of mild heating which is sufficient to kill the
microorganisms that can cause spoilage problem without really damaging the
taste of the product.
pasteurization
at what degree is the heat treatment for milk
Heat treatment for milk (72 degC for about 15 secs) kills all pathogens and
most non-pathogens
pasteurization is used in
Milk, cream, and certain alcoholic beverages (beer and wine)
MOA of pasteurization
protein denaturation
kills by oxidation effect
dry heat
Very effective method of sterilization
direct flaming
direct flaming is used in
inoculating loops
MOA of direct flaming
Burning contaminants to ashes
very effective method of sterilization
incineration
incineration is used in
Paper cups, contaminated dressings, animal carcasses, bags and wipes.
MOA of incineration
burning to ashes
very effective method of sterilization but requires temp.at 170 degC for
about 2 hours.
Hot-air sterilization
Hot-air sterilization is used in
Empty glasswares, instruments, needles and glass syringes.
MOA of hot-air sterilization
oxidation
the passage of a liquid or gas through a screen like materials
with pores small enough to retain microbes.
filtration
filtration is used in
Sterilizing liquids (enzymes, vaccines) that are destroyed by heat
MOA of filtration
Separation of bacteria from suspending liquid
Has a bacteriostatic effect
refrigeration
ref.. is used in
Food, drug and culture preservation
MOA of ref..
Decreased chemical reactions and
possible changes in protein.
an effective method for preserving microbial cultures, in which cultures are
quick-frozen
deep-freezing
cultures are
quick-frozen between
-50 degC and 95 degC
deep-freezing is used in
Food, drug and culture preservation
MOA of deep-freezing
Decreased chemical reactions and possible changes in protein.
Most effective method for long term preservation of microbial culture
Water removed by high vacuum at low temp.
Lyophilization
Lyophilization is used in
Food, drug and culture preservation
MOA of Lyophilization
Decreased chemical reactions and possible changes in protein.
Preservation of colors, nutrient values
high pressure
high pressure is used in
fruit juices
high pressure MOA
Alteration of molecular structure of proteins and
carbohydrates.
Involves removing of water from microbes; primarily
bacteriostatic
desiccation
desiccation is used
food preservation
MOA of dessication
Disruption of metabolism
Results in loss of water from microbial cells
osmotic pressure
osmotic pressure is used in
food preservation
MOA of osmotic pressure
Plasmolysis
kills microorganism
radiation
2 ways of killing microorganism thru radiation
ionizing and non-ionizing
Not widespread in routine sterilization
Ionizing (gamma rays or high enery electron)
ionizing use:
Sterilizing pharmaceuticals and medical and dental supplies
MOA of ionizing
Destruction of DNA
radiation not very penetrating
non-ionizing
non-ionizing is used in
Control of closed environment with UV lamp
principles of effective disinfection
read the label
nature of material being disinfected
disinfectant effect
chemical substances that applied to non-living objects or surfaces to
inhibit the growth of microorganisms.
disinfectant
prevent the spreading of germs and bacteria to people by sterilizing the surfaces
where they are applied and they are largely used in homes for cleaning bathrooms, kitchens and floor.
disinfectant
disinfectant used in healthcares
hydrogen peroxide
common disinfectant
alcohols, oxidizing agents and bleaches.
chemical agents used to destroy or prevent the growth of microorganisms
that could cause infections and diseases.
antiseptic
applied on broken skins to kill disease-causing microorganisms that might have infected the area or keep them away from these areas and are applied on living tissues with zero injurious effect on the body surface where it is
applied.
antiseptics
may also act as sanitizer for cleaning hands to remove bacteria when a person
cannot wash hands.
antiseptics
Applied on non-living items
Inhibit the growth of microorganisms on the
surfaces
Disinfect areas that can spread germs
Very toxic and injurious when used on living
tissue
disinfectant
Applied on living tissues
Kill and destroy microorganisms on living
tissue
Reduce the risk of infections by germs.
Have no injurious effect on living tissue.
antiseptics
Used in: Original surgical antiseptic.
Mechanism of Action: Denatures proteins and disrupt cell membrane
phenol (carbolic acid)
Used in: Disinfectants, antiseptics and solvent in tincture
Mechanism of Action: Denatures proteins and disrupt cell membrane
alcohol
Used in: Disinfectants, antiseptics and water purification
Mechanism of Action: Denatures proteins and disrupt cell membrane
Halogen (iodine, chlorine, bromine)
Used in: Disinfectants, antiseptics for deep wound , water purification and
sterilization of food processing and medical equipments.
Mechanism of Action: Denature protein by oxidation
Oxidizing Agents (peroxides,ozone)
Mechanism of Action: Decrease surface tension of water and disrupt cell
membranes
Used in: Soaps, degerming reagents, antiseptics
surfactants
Used in: Fungistat in paints, silver nitrate cream, surgical dressing, burn cream and
catheter.
Mechanism of Action: Denature protein
Heavy Metals (arsenic, mercury, silver copper)
Used in: Disinfectan and embalming fluid
Mechanism of Action: Denature protein
Aldehydes (Formaldehyde,glutaraldehyde)
Used in: Sterilization of heat and water sensitive objects
Mechanism of Action: Denature protein
Gaseous analytes (ethylene oxide)
Used in: Disinfectants and treatment of infectious diseases
Mechanism of Action: Act against cell wall, cell membranes, protein
synthesis and DNA replication.
antimicrobials
Actions of microbial control agents
Alteration of membrane permeability
Damage to protein and nucleic acids
