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define sterilization
the removal of all microbes
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define aseptic
an environment or procedure free from contamination
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define disinfection
the use of chemical or physical agents to kill or inhibit the frowth of microorganisms
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define de-germing
the removal of microbes from a surface by mechanical means
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define sanitization
- deisinfection of places or things used by the public
- used to reduce the # of pathogens to meet accepted public health standards
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define pasteurization
sing heat to kill pahtogens
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define antisepsis
disinfecting on skin (like using alcohol wipe) and in tissue
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define what the ending cide/cidal means
kills bacteria or organism
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define the ending static/stasis means
inhbit growth
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defn microbial death
is difficult to determine, so there are special reuirements to define microbial death
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what are factors that affect the rate of microbial death?
- numbers-
- the greater the # of organisms, the longer it will take to kill all of them.
- duration of exposure-
- can vary depending on the accessibility of the agen to the organism as well as the microbe in q.
- temperature- lower the temp at which the microbes are treated, the longer it will take to kill all of them
- environment
- endospore formation-
- endospores are resistent to many of the agents routinely used to inhibit microbial growth
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what are the four targets of antimicrobial agents?
- integrity of cell wall
- integrity of the cell membrane
- the shape & function of proteins
- induce mutations and halt proteins synthesis of nucleic acids
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what does radiation damage do to DNA?
- can interfere w/ DNA & RNA function
- -irradiation w/ gamma rays, UV radiation & x-rays causes mutations
- -these can result in permanent inaactivation of nucleic acids
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what are the 3 major roles for controlling microbial growth?
- chemical
- physical
- mechanical removal
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describe the methods for controlling microbial growth
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what 3 factors do you need to consider when evaluating the effectiveness of disinfectants& antiseptics?
- time
- temperatre
- concentration
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The effects of chemical agents varies with?
- temperature
- length of exposure
- amount of contaminating organic material
- pH
- concentration
- stability
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how do the potency of disinfects & antiseptics differ for chemicals & alcohol?
- for most chemical agents, increasing cncentration, increase its potency
- not true of alcohol; as concentration increases killing is hindered; must have some water (makes for better penetration & determination of proteins)
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what are the tests used to evaluate disinfectents & antiseptics?
- comparison of the agent w/ phenol coefficient
- disk method
- use dilution method
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explain the disk method.
- uses tiny disks of filter paper soaked in the agent
- an agar plate is inoculated & the disks are placed at various positions
- inhibition of growth around the disk is called the zone of inhibition (sizes of the zone are not comparable, sizes may reflect differences in concentration & dffusion rates)
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name the 8 major categories of chemical agents.
- phenol and phenolic compounds
- alcohols
- halogens
- oxidizing agents
- surfactants-soaps
- heavy metals
- aldehydes
- gaseous agents
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describe the types of chemical agents
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explain the types of physical methods
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