Lesson 13 Flashcards
-The goal controlling microorganisms is twofold what are this?
(a) to destroy pathogens and prevent their transmission
(b) to reduce or eliminate microorganisms responsible for the contamination of water, food, and other substances
-microorganism are controlled by what?
Physical agents
Chemical agents
: a process by which an article, surface, or medium is freed of all living microorganisms either in the vegetative or in the spore state
Sterilization
-any material that has been subjected to the above process.
sterile
-: a chemical agent that is used to perform sterilization because of their ability to destroy spores.
Sterilants
-: also called a microbicide, is any chemical agent that kills pathogenic microorganisms either on inanimate (nonliving) materials or on living tissue but not resistant microbial cells.
Germicide
the use of a chemical agent that destroys or removes all pathogenic organisms or organisms capable of giving rise to infection or its harmful products (toxin) thus destroys vegetative pathogens but not bacterial endospores. Used only on inanimate objects because they can be toxic to human and other animal tissue,when used in higher concentrations.
Disinfection
. -: is defined as the growth of microorganisms in the body or the presence of microbial toxins in blood and other tissues
Sepsis
.-: refers to any practice that prevents the entry of infectious agents intosterile tissues and thus prevents infection.
Asepsis
-: are chemical agents applied directly to the exposed body surfaces(e.g., skin and mucous membranes), wounds, and surgical incisions to destroy orinhibit vegetative pathogens.
Antiseptic
-: is any cleansing technique that mechanically removes
microorganisms (along with food debris) to reduce the level of contaminants.
Sanitization
-: a compound (e.g., soap or detergent) that is used to perform sanitization. Air sanitization with ultraviolet lamps reduces airborne microbes in hospital rooms, veterinary clinics, and laboratory installations.
Sanitizer
reduces airborne microbes in hospital rooms, veterinary clinics, and laboratory installations.
Air sanitization with ultraviolet lamps
-a process usually involves scrubbing the skin or immersing it in chemicals, or both. It also emulsifies oils that lie on the outer cutaneous layer and mechanically removes potential pathogens from the outer layers of the skin
Degerming/antiseptis
-Methods of controlling microorganisms
Sterilization
Disinfection
Antimicrobials
Physical methods of sterilization
Sunlight
Heat
Filtration
Radiations
Sonication
-a natural method of sterilization of water in tanks, rivers, and lakes. has an active germicidal effect due to its content of ultraviolet and heat rays
sunlight
-one of the most dependable method of sterilization.
Heat
- higher temperatures (exceeding the maximum) are what ?
,
microbicidal
- lower temperatures (below the minimum) tend to have what?
inhibitory or microbiostatic effects.
-kills microorganisms by denaturation and coagulation of proteins
Moist heat sterilization
-temperature range in moist heat sterilization
-
60-135 degree Celsius
is a technique in which heat is applied to liquids to kill potential agents of infection and spoilage, while at the same time retaining the liquid’s flavor and food value.
Pasteurization
This method is extensively used for sterilization of milk and other fresh beverages, such as fruit juices, beer, and wine which are easily contaminated during collection and processing.
Pasteurization
-product is exposed to heat at 72°C for 15–20 seconds followed by a sudden cooling to 13°C or lower
Flash method
- product is exposed to a temperature of 63°C for 30 minutes followed by cooling to 13°C or lower, but not less than 6°C).
holder method
inactivates most viruses and destroys the vegetative stages of 97–99% of bacteria and fungi, it does not kill endospores or thermoduric species (mostly nonpathogenic lactobacilli, micrococci, and yeasts)
Pasteurization
-Simple boiling of water for 10–30 minutes kills most of the vegetative forms of bacteria but not bacterial spores thus only for disinfection.
Boiling
: substances are exposed to steam at atmospheric pressure for 90 minutes during which most vegetative forms of the bacteria except for the thermophiles are killed by the moist heat.
Steam sterilizer at 100°C
-Certain heat-labile substances (e.g., serum, sugar, egg, etc.) that cannot withstand the high temperature of the autoclave
Intermittent sterilization or tyndallization
-Certain heat-labile substances (e.g., serum, sugar, egg, etc.) that cannot withstand the high temperature of the autoclave
Intermittent sterilization or tyndallization
is used most often to sterilize heat-sensitive culture media, such as those containing sera and some canned foods
Intermittent sterilization
- is carried out over a period of 3 days and
requires a chamber to hold the materials and a reservoir for boiling water.
Tyndallization
-makes use of air with a low moisture content that has been heated by a flame or electric heating coil.
Sterilization by dry heat