Sterilization And Disinfection Test Questions – Flashcards
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| control of infectious disease agents |
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| 1. public sanitation 2. sterilization and disinfection procedures 3. chemotherapeutic agents (antibiotics) 4. bodies defense mechanisms |
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| sterilization |
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| total destruction of all microbes |
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| disinfection |
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| destruction of most pathogenic microbes -remaining are nonpathogens and spores of pathogens |
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| bacteriocidal |
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| agent that kills bacteria |
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| bacteriostatic |
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| agent that inhibits bacterial growth |
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| antiseptic |
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| chemicals with low human toxicity that destroy mcroorganisms capable of caughing contamination or disease |
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| factors affecting sterilization/disinfection action |
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| 1.time 2.temp 3.ph 4. # of microorganisms 5. types of microorganisms 6.presence of extraneous matter 7.proper exposure 8. concentration of disinfectand or sterilant |
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| methods of physical control |
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| 1. heat-high temps inactivate proteins and nucleic acids by breaking their hydrogen bonds 2. radiation-causes chemical changes to the nitrogenous bases of nucleic acids 3. filtration-physical removal of organisms from the solution that is filtered |
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| heat |
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| -most widely used method for microbial control -decimal reduction time or D value--measures on organisms heat resistance |
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| heat sensitive tape |
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| tape impregnated with chemicals that change color when exposed to a critical temperature |
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| biological monitor |
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| spore strips of clostridium or bacillus |
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| heat treatment procedures |
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| dry heat moist heat boiling water pasteurization --flash pasteurization |
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| dry heat |
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| generated by an oven condition: 160 celcius, 2 hrs--kills spores usage: sterilization of lab glassware disadvantage- high temp, chars organic materials |
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| moist heat |
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| generated by an autoclave (industrial pressure cooker) condition: 121 degrees celsius. 15 min, 15 lb/in^2 --kills spores usage: sterilization of microbiological media, glassware and ommercial canning disadantage: expensive equipment |
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| boiling h20 |
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| water bath or chamber condition- 100 celcius for 30 min-kills all non spore forming microorganisms usage: hospitals-disinfect bedding/clothing of patients home-boil unsafe drinking water, disinfect baby items disadvantage-items easily recontaminated when removed from h20 |
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| pateurization |
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| process of using mild heat to kill pathogens while preserving the quality and flavor of food condition-62-66 celcius, 30 min, quick cool (time and temp conditions required to kill coxiella burnetti) usage-destruction of pathogens in milk, beer and wine----increases shelf life |
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| flash pasteurization |
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| newer technique condition- 71.7 celsius, 15s, quick cool |
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| radiation |
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| emission and propagation of energy thru space or thru a substance in the form of waves a. uv light-non ionizing (100-400 nm wavelength) b. ionizing radiation |
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| bacteriocidal wavelength |
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| 25-=270nm dna absorbs uv light which induces a rearrangment in hydrogen bonding of the dna strant. these changes result in copying errors which increase the probability of a lethal mutation |
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| germicidal lamp (mercury vapor lamp) |
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| -generates radiation at 254nm usage: disinfection rather than sterilization lamps are placed in air ducts or directly over surface. uv lamps are placed in air supply ducts of operating rooms, food preperation areas, nursing homes and nurseries -effectveness: reduces the concentration of air-borne microbes by 99% -disadvantage: limited use since uv light is absorbed by solids-damaging to human tissues (skin and eye) - sunburn, wrinkles, cancer and retinal damage |
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| ionizing radiation |
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| -shorter wavelength that uv, increased energy, energy in absorbed by atoms --> ions (gain/loss of electrons) ionization---> forms primarily free hydroxyl radicals which react with cellular proteins and nucleic acids, inducing chemical alterations that are cidal usage: sterilizing medical products, tissues, bone, skin, meat, fruit, veggies -advantages: speed, high penetration power-ability to penetrate fabrics, plastics, liquids and foods for sterilization disadvantage- radiation exposure |
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| filtration |
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| sterilization for removing microbes but not destroying them |
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| filter membrane |
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| cellulose acetate, polycarbonate, variety of plastics (teflon or nylon) 0.22 micromete pore size removes all bacteria 0.025 micromete pore size removes all viruses |
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| liquid filtration |
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| -used to sterilize liquids that cannot withstand heat (serum, blood products, vaccines, antibiotics, iv fluids, enzymes) water purification |
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| air filtration |
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| HEPA used in air ducts to critically clean areas |
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| HEPA filter |
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| high efficiency particulate air filters -tightly woven fiberglass medium which remove particles as small as 0.3 micrometers with 99.9% efficiency -usage HEPA filters are installed in air supply systems to operating rooms, nurseries, ICUs and biohazard hoods |
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| alcohols |
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| ethyl alcohol and isopropyl alcohol effective antiseptics when applied as 70-80% aqueous solutions -mode of action: alcohols precipitate proteins and solubiliza lipids present in the cell walls and cell membranes of bacteria usage: human skin antiseptic effectiveness: kills vegetative cells but not sporicidal |
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| halogens |
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| iodine idophors chlorine |
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| iodine |
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| effective antiseptic when solubilized in 70% ethyl alcohol (tincture) mode of action: inactivates proteins and organic molecules by reacting w hydroxyl groups usage-human skin antiseptic, treating cuts and abrasions |
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| idophors |
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| iodines complexed with soap -usage: preoperative skin disinfectant -advantage: soluble in h20 and gradually releases iodine -disadvantage: not as effective as tincture |
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| chlorine |
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| reacts with h20 to from HC10-strong oxidant -oxidizes sulfhydral groups of cell proteins -clorox-contains 5.25% sodium hypochorite usage: sanitize toilets,dishes, food processing equipments |
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| formaldehyde and glutaraldehyde |
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| same mechanism to kill microbes mode of action- both alkylating agents subsitite alkyl groups for the h atoms of reactive groups of enzymes, nucleic acides and proteins. -formaldehyde: gaseous state, usage: fumigant, disadvantage: noxious vapos, irritate tissues |
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| formaldehude sol'n |
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| formalin usage: tissue fixative,inactivator of vaccines, embalming fluid disadvantage: tissue irritant |
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| glutaraldehyde sol'n |
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| usage: effective cold sterilizing agent - primary use is sterilization of dental equipment disadvantage: irritates tissues, mildly disagreeable odor |
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| copper, mercury and silver |
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| heavy metals toxicity is due to their ability to combine with active chemical (sulfhydral) groups on proteins |
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| copper sulfate |
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| usage: algaecide, additive to marine bottom paints- inhibits attachment of mussels and barnacles |
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| mercurials |
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| mercury containing compounds usage: additive to ointments and sol'ns used in the topical treatment of skin infections disadvangve: toxicity, allergic rxns, and neutralization by organic matter |
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| silver nitrate |
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| usage: 1% soln of silver nitrate used as eye drops for newborn infants to prevent infections by gonorrhoeae |
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| silver sulfadiazine |
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| additive to ointments used to prevent infections in burn patients |
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| ethylene oxide |
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| bactericidal, fungicidal and sporicidal (12 hours, 70 celsius kills spores) usage-sterilizing agents for plastics advantage-ability to sterilize at moderate temps with no moisture |
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| quaternary ammonium compounds (quats) |
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| bacteriocidal for a wide range of vegetative bacteria -mode of action- kills cells by disrupting their cytoplasmic membrane -usage-disinfect floors, walls, etc (also used for prepping vagina and other sensitive mucous membrane structures for surgery) -advantage-odorless, colorless, tasteless, inexpensive, non-toxic to mammalian tissue, soluble in water and active in low concentrations -disadvantages-readly inactivated by organic or inorganic substances |
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| phenols |
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| lower toxicity phenolics are effective disinfectants, non-sporicidal -mode of actions-denature proteins, and disrupt cell membranes -advantage-reasonable cost, compatibility with detergents, resistance to inactivation by organic matter -hexachlorophene-effectively kills staphylococci usage-1960s as an antiseptic for bathing newborns -disadvantage-absorption thru skin linked to brain damage in infants -usage today: prescription only |
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| hydrogen peroxide |
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| bactericidal or sporicidal dependent on concentration: 3-6% kills bacteria, 10-25% kills spores -mode of action: oxidizing agent that inactivates essential protein structures -usage: a 3% solution is used to cleanse wounds and disinfect plastic implanst, contact lenses and surgical prostheses -advantage: non-irritating to tissues |
