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39 Cards in this Set
- Front
- Back
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sterilization (definition)
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the destruction or removal of all viable organisms
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disinfection (definition)
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killing, inhibition, or removal of disease causing (pathogenic) organisms
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sanitization (definintion)
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the reduction of microbial population to levels deemed safe (based on public health standards)
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antisepsis (definition)
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prevention of infection of living tissue by microorganisms
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antiseptics (definition)
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chemical agents that kill or inhibit the growth of microorganisms when applied to tissue
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antimicrobial agents (definintion)
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agents that kill microorganisms or inhibit their growth
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chemotherapy (definition)
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the use of chemicals to kill or inhibit the growth of microorganisms within host tissue
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-cidal agents
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suffix indicating that the agent kills ex. bactericides, fungicides, algicides, and viricides |
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-static agents
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suffix indicating that the agent inhibits growth ex. bacteriostatic and fungistatic |
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the pattern of microbial death |
- microorganisms are not killed instantly - population death usually occurs exponentially - measure of an agents killing efficiency: > must be sure persister cells (viable but nonculturable (VBNC) condition) are dead > once they recover, they may regain the ability to reproduce and cause infection |
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conditions influencing the effectiveness of antimicrobial agent activity: population size |
larger populations take longer to kill than smaller populations |
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conditions influencing the effectiveness of antimicrobial agent activity: population composition |
microorganisms differ markedly in their sensitivity to antimicrobial agents
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conditions influencing the effectiveness of antimicrobial agent activity: concentration or intensity of the antimicrobial agent |
usually higher concentrations kill more rapidly but the relationship is not linear |
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conditions influencing the effectiveness of antimicrobial agent activity: duration of exposure |
longer exposure = more organisms killed
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conditions influencing the effectiveness of antimicrobial agent activity: temperature |
higher temperatures usually increase killing |
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conditions influencing the effectiveness of antimicrobial agent activity: local environment |
- pH, viscosity, concentration of organic matter, etc. can profoundly impact effectiveness - organisms in biofilms are less susceptible to many antimicrobial agents |
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mechanisms of removal: filtration |
- reduces microbial population or sterilizes solutions of heat sensitive materials by removing microorganisms - also used to reduce microbial populations in the air |
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mechanisms of removal: filtration > filtering liquids (membrane filters) |
porous membranes with defined pore sizes that remove microorganisms primarily by physical screening
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mechanisms of removal: filtration > filtering air |
- surgical masks > N-95 >95% of particles < 0.3 um - cotton plugs on culture vessels - high efficiency particulate air (HEPA) filters > used in laminar flow biological safety cabinets |
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HEPA filters
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- fiberglass depth filter - 99.97% of particles < 0.3 um - used in laminar flow biological safety cabinets > contaminated air does not escape into the room |
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physical control methods: moist heat |
- destroys viruses, fungi and bacteria - boiling will not destroy spores and does not sterilize - degrades nucleic acids, denatures proteins and disrupts membranes |
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physical control methods: steam sterilization
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- carried out about 100 degrees Celsius which requires saturated steam under pressure - uses an autoclave > water is boiled to produce steam > steam must touch the sample > 121 C and 100 kPa > time depends on sample - effective against all types of microorganisms including spores |
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physical control methods: pateurization
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- controlled heating at temps way below boiling > 63 C for 30 mins = classic batch > 72 C for 15 sec = flash > 134 C for 1 sec = ulta-high temp pasteurization > 140 C for 1-3 sec = ultra-high temp sterilization - used for milk, beer and other beverages - does not sterilize but does kill pathogens present and slows spoilage by reducing the total load of organisms present |
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physical control methods: dry heat sterilization
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- less effective than moist heat sterilization - requires higher temps and longer exposure time > items subjected to 160-170 C for 2-3 hours - oxidizes cell constiuents and denatures proteins |
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physical control methods: dry heat incineration
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- bench top incinerators are used to sterilize inoculating loops
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physical control methods: UV radiation
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- wavelength of 260 nm is most bactericidal - causes thymine dimers which prevent replication and transcription - limited to surface sterilization because it does not penetrate glass, dirt films, water, and other substances - has been used for water treatment |
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physical control methods: ionizing radiation
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- gamma radiation penetrates deep into objects - destroys bacterial endospores but not always effective against viruses - used for sterilization and pasteurization of antibiotics, hormones, sutures, plastic disposable supplies, and food |
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chemical control agents: disinfection |
must be effective against a wide variety of infectious agents at low concentrations
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chemical control agents: antisepsis
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- overuse of antiseptics like triclosan has selected for triclosan resistant bacteria and possibly antibiotic resistance > triclosan is now banned by the US FDA |
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chemical control agents: sterilization
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chemical agents
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must be effective in the presence of organic matter and should be stable in storage |
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phenolics
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- commonly used at laboratory and hospital disinfectants - act by denaturing proteins and distrupting cell membranes - tuberculocidal, effective in the presence of organic material, and long lasting - disagreeable odor and can cause skin irritation |
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alcohols
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- among the most widely used disinfectants and antiseptics - two most common are ethanol and isopropanol - bacterialcidal, and fungicidal but not sporicidal - can inactivate some viruses - denature proteins and possibly dissolve membrane lipids |
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halogens: iodine
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- skin antiseptic - oxidizes cell constituents and iodinates proteins - may kill spores at high concentrations - may cause skin damage, staining or allergies - iodophore: iodine complexed with organic carrier > releases slowly to minimize skin burns |
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halogens: chlorine |
- oxidizes cell constituents - important in disinfection of water supplies and swimming pools, used in the dairy and food industry, and effective household disinfectant - destroyes vegetative bacteria and fungi - chlorine gas is sporocidal - can react with organic matter to form carcinogenic compounds |
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heavy metals: ions of mercury, silver, arsenic, zinc and copper
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- effective but usually toxic - combine with and inactivate proteins and may also precipitate proteins |
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quaternary amonium compounds
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- detergents that have antimicrobial activity and are effective disinfectants > amphipathic organic cleansing agents - cationic detergents are effective disinfectants > kill most bacteria but not M. tuberculosis or endospores > safe and easy to use, inactivated by hard water and soap |
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aldehydes
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- commonly used agents are formaldehyde and glutaraldehyde > highly reactive molecules - sporocidal and can be used as chemical sterilants - combine with and inactivate nucleic acids and proteins |
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sterilizing gases
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- used to sterilize heat sensitive material - microbicidal and sporicidal - ethylene oxide sterilization is carried out in equipment resembling an autoclave > betapropiolactone and vaporized hydrogen peroxide - combine with and inactivate DNA and proteins |
