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86 Cards in this Set
- Front
- Back
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what does sterilization target
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spores
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ancient methods used for controlling microbial growth
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-use of fire -filtration of wine and water -salting, smoking, pickling, drying -sunlight |
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the destruction or removal of microbes responsible for infections or spoilage
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microbial control
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bacterial endospores
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high resistance
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fungal spores, protozoan cysts
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moderate resistance
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most bacteria vegetative form
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least resistance
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the removal of all life forms, inanimate objects
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sterilization
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microbicidal agents
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kill
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microbistatic agents
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prevent from further growing
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the destruction of vegetative pathogens (but not bacterial endospores) using a chemical agent or physical process
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disinfection
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generally limited to inanimate objects, because these agents and processes can be toxic to human and animal tissues
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disinfectants
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methods used to inhibit or destroy vegetative pathogens from body surfaces, wounds, and surgical incisions (washing hands, pre-op scrub, H2O2 flush of root canal)
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antisepsis
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reduction of the microbial load (from inanimate objects) to a safe level
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sanitization
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reduction of the number of microorganisms from the skin surfaces
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degeneration
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permanent loss of reproductive capabilities
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microbial death
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factors effecting death rate
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-contact time with the agent -concentration of agent -cell activity (young v old) -microbial load -type of bacterial population -mode of action of agent -presence of interfering material |
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these agents attack specific cell sites to cause microbial death or damage, their effectiveness is against a variety of microorganisms
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antimicrobial agents
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mode of action of antimicrobials
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-cell wall effect -cause damage to cell membrane -nucleic acid and protein synthesis -protein function |
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agents that effect the cell wall
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digestion of cell wall/block synthesis lysis |
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agents that cause damage to cell membrane
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loss of cell membrane selective permeability cell death |
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agents on nucleic acids and protein synthesis
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causes mutation: gamma ray, X ray, UV light may interfere with RNA and DNA function causes altered protein synthesis at the ribosome site |
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effects of agents on protein function
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protein denaturation unfolding of protein changes in bacterial metabolism |
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general characteristics of heat
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bactericidal or static dry or moist |
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heat applied at lower temps and shorter exposure time
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moist heat
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effects of moist heat on bacteria
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denaturation and coagulation of proteins cellular damage irreversible cessation of cellular metabolism |
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dry heat effects on bacteria
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protein denaturation cell dehydration cell oxidation-ash |
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most bacterial spores are killed at temperatures greater than
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100 degrees Celsius
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killed by using lower temperatures and shorter time
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vegetative form
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what is the thermal death time
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the shortest length of time required to kill a bacterial population at a given temp
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thermal death point
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minimal temperature that kills all microorganisms in a specimen at a given time (important in can food industry)
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types of moist heat
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-steam under pressure -fractional or intermittent sterilization -pasteurization -boiling water |
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steam under pressure
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autoclave -as pressure in a closed system increases so does the temp of boiling water and steam temp reduces sterilization time |
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fractitional or intermittent sterilization
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used when material are not suitable to high temps in autoclave sterilization used by exposure to steam at 100 degrees Celsius for 30 minutes on 3 consecutive days |
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disinfections of beverages
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pasteurization
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used for reducing bacterial population in a liquid, will cause destruction of organisms that cause spoilage, will give drinks longer storage time, and destroy contaminants at breweries and wineries
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pasteurization
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effective for disinfecting drinking water
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boiling water
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hot air that will destroy spores at temperature of 150-180 degrees C for 2 to 4 hours, disadvantage: requires long time
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dry heat
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by using Bunsen burners, furnaces,etc
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incineration
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effects of cold
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-slows down growth of bacteria -slows down growth of microorganisms in food |
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exposure to normal room temp results in loss of water content in bacterial cells, which can lead to bacterial cell death
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dehydration (desiccation)
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lyophilization
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-material is deep frozen and then -liquid is drawn off by a vacuum -this prevents formation of ice crystals -allows future reconstitution of the cells |
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have shorter wave lengths/more power than UV light
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ionizing radiation (gamma, x-rays)
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create ions when they pass through microbial cells, causing destruction of bacterial proteins and nucleic acids, they cause death of bacterial cells
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ionizing radiation
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applications for ionizing radiation
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-sterilization for heat-sensitive pharmaceuticals (vitamins, antibiotics,etc) -sterilization for plastic or certain suture material -reduction of pathogenic agents in meat -irradiated food requires label |
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they have wave lengths of 100-400 nm that are very destructive, alters DNA strands, replication and transcription effected, inhibits proteins and cell growth
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non-ionizing radiation (UV light)
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application of UV light
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-effective in reducing microbial count where direct exposure takes place -germicidal lamps -does not penetrate liquids or solids,may cause damage in human skin cells and retina |
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cause cell disruption by sonication
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sound waves (ultrasonic vibration)
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many gram negative rods are sensitive to this
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ultrasonic vibration
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applications of ultrasonic vibration
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-cleaning instruments -removing plaque and calculus from teeth |
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used to remove microorganisms from the air and liquids
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filtration
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application of filtration
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-water -sterile air in hospital rooms -sterilization of heat sensitive liquids (does not remove soluble toxins) |
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modes of action of most germicides include targets such as
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-cell membrane -cell wall -nucleic acids -proteins |
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chemical agents used to control growth of microorganisms
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disinfectants
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leads to destruction of pathogenic microorganisms on nonliving objects, most bacteriostatic, few gases bactericidal, used as antiseptic
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disinfection
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properties of antiseptic and disinfectant
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-ability to kill microorganisms that interfere with their metabolism -best if they are nontoxic -water soluble -long shelf life -effective at diluted concentrations |
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oxidize proteins
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halogens (FI,br,CL, I)
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chlorine and iodine are useful for
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-prep surgical sites -water disinfectants -wound antisepsis -sanitation -killing endospores, fungi, and viruses -common household bleach |
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has antibacterial activities against vegetative forms of bacteria, alters cell membrane selective permeability/causes protein denaturation
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chlorhexidine
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advantages of chlorhexidine
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-low toxicity -mild -rapid action -not absorbed into deeper tissue |
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chlorhexidine applications
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-sx site prep -hand scrubbing, neonatal wash -wound degermer -preservative for eye solution |
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heavy metals
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silver, gold, copper, arsenic, and zinc
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modes of action of these heavy metals
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-antiseptics (mouth ulcers, germicides, root canals) -burns -disinfectants |
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modes of action depend on concentration: denature protein, disrupt bacterial membranes, 70% solution is effective skin antiseptic
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alcohols
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which alcohol concentration has a greater microbial activity 100 or 70%
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100% water is needed for protein to coagulate absolute alcohol dries out the cells and inhibits their growth but does not function as a protein coagulant |
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caused inactivation of proteins and nucleic acids (formadehyde)
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aldehydes
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aldehyde that disrupts protein structure and enzyme activity and is less toxic than formaldehyde
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glutaraldehyde
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an irritant gas that dissolve in water to form formalin (pure-37%) interferes with amino acid synthesis, high toxicity and carcinogenic
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formaldehyde
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used for sterilization of material hat would be damaged by heat (fiber optic, endoscopes), used on dental instruments to prevent transmission of some blood-born infections, used to sanitize poultry carcasses and degerm cow's treats
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glutaraldehyde
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react with DNA molecules and proteins, and ultimately block DNA replication and enzymatic activity
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ethylend oxide and other gases
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under control, is good sterilant for plastic, but is carcinogenic
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ethylene oxide
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decomposes in the presence of light and catalyzes into water and oxygen
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hydrogen peroxide
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the germicidal effect of hydrogen peroxide is due to the action of
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oxygen
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limited use due to corrosive effects
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acids and alkalis
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organic acids can be used in food
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vinegar in pickling lactic acid in sauerkraut/olive stop anaerobic bacteria |
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detergents react with
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membranes
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molecules that act as surfactants
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detergents
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cause cell membranes to lose selective permeability
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surfactants
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used for degermination in sops, weak microbicides
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detergents
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destruction, removal or reduction in number of undesirable microbes (asepsis, disinfecion, sanitation)
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decontamination
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growth of microorganisms in the tissues
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sepsis
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technique that prevent entry of microorganisms into sterile tissue
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asepsis
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chemicals applied to surface of the body to destroy or inhibit vegetative pathogens
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antiseptic
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destruction of vegetative pathogens on inanimate objects
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disinfection
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cleansing technique that removes microorgansims and debris from inanimate objects
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sanitation
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cleansing technique that removes microorganisms and debris from living tissue
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degermination
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removal or destruction of all viable microbes
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sterilization
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