Chapter 9 – Microbiology – Flashcards
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| sterilization |
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| refers to the removal of the destruction of all microbes, including viruses and bacterial endospores |
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| prions |
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| infectious proteins very resistant, not killed during standard sterilization procedures |
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| aseptic |
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| describes an environment or procedure that is free of contamination by pathogens |
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| disinfection |
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| refers to the use of chemical or physical agents known as disinfectants to inhibit or destroy microorganisms, especially pathogens -term only used for inanimate objects |
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| disinfectants |
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| physical or chemical agents used to inhibit or destroy microorganisms especially pathogens -ie: UV light, heat, alcohol, bleach |
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| antisepsis |
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| less concentrated disinfectants to be used on skin or tissue |
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| antiseptic |
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| less concentrated disinfectant chemical used on the skin or tissue |
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| degerming |
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| removal of microbes from a surface by scrubbing |
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| sanitization |
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| process of disinfecting places and utensils used by the public to reduce the number of pathogenic microbes to meet accepted public health standards |
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| pasteurization |
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| the use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages |
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| -stasis/static |
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| suffixes which indicate that a physical or chemical agent inhibits microbial growth, but does not necessarily kill microbes |
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| -cide/cidal |
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| suffixes that refer to agents that destroy or permanently inactivate a particular type of microbe -ie: virucides, bactericides, fungicides |
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| microbial death |
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| permanent loss of reproductive activity under ideal environmental conditions |
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| microbial death rate |
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| technique in evaluating the efficacy of an antimicrobial agent |
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| most resistant microbes |
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| -bacterial endospores -species of Mycobacterium -cysts of protozoa **prions are more resistant than any living thing |
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| high level germicides |
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| kill all pathogens, including bacterial endospores |
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| intermediate level germicides |
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| -kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria -does not kill bacterial endospores |
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| low level germicides |
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| eliminate vegetative bacteria, fungi, protozoa, and some viruses |
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| phenol coefficient |
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| calculating a ratio that compares a given agent's ability to control microbes to that of phenol under standardized conditions -the larger the ratio, the greater the effectiveness |
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| use-dilution test |
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| -researcher dips several metal cylinders into broth cultures of bacteria, and briefly dries them at 37*C -each contaminated cylinder immersed into different dilutions of the disinfectants being evaluated -most effective= the one that entirely prevents microbial growth at the highest dilution |
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| Kelsey-Sykes capacity test |
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| -researchers add a suspension of bacterium to a suitable concentration of the chemicals being tested -at predetermined times, they move samples of the mixture into growth medium containing a disinfectant deactivator -lack of turbidity reveals the minimum time required for the disinfectant to be effective |
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| in-use test |
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| -more realistic method -swabs are taken from actual objects (ie, operating room equipment) both before and after the application of a disinfectant or an antiseptic |
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| thermal death point |
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| the lowest temperature that kills all cells in a broth in 10 minutes |
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| thermal death time |
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| the time it takes to completely sterilize a particular volume of liquid at a set temperature |
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| decimal reduction time |
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| the time required to destroy 90% of the microbes in a sample |
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| moist heat |
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| -commonly used to disinfectant, sanitize, sterilize, and pasteurize -kills cells by denaturing proteins and destroying cytoplasmic membranes -works better than dry heat because water is a better conductor of heat than air -includes: boiling, autoclaving, pasteurizing, and ultrahigh temperature sterilization |
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| boiling |
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| -moist heat -kills the vegetative cells of bacteria and fungi, the trophozoites of protozoa, and most viruses within 10 minutes at sea level -note: it is impossible to boil something more quickly just by adding more heat; the added heat is carried away by the escaping steam |
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| autoclaving |
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| -sterilizing by means of higher temperatures than boiling water -pressure is added to the boiling water in order to prevent the escape of steam and ultimately achieve the required temperature |
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| autoclaving |
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| -sterilizing by means of higher temperatures than boiling water -pressure is added to the boiling water in order to prevent the escape of steam and ultimately achieve the required temperature |
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| autoclave |
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| -device that uses steam heat under pressure to sterilize chemicals and objects that can tolerate moist heat -standard settings for sterilization: 121*C, 15 psi, 10 minutes -sterilization requirements: steam must be able to contact all liquids and surfaces that might be contaminated with microbes |
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| pasteurization |
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| -a method of heating food and/or beverages just enough to kill the microorganisms that cause spoilage without ruining the taste -not a form of sterilization, thermophilic and thermodurmic prokaryotes survive -batch method= 63*C for 30 min -flash pasteurization= 72*C for 15 sec -ultra-high temperature= 134*C for 1 sec |
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| ultra-high temperature sterilization |
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| -flash heating milk or other liquids in order to rid them of all living microbes -liquid is passed through superheated steam at 140*C for 1-3 sec and then cooling it rapidly |
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| dry heat |
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| -sterilization with dry heat requires higher temperatures for longer times than moist heat b/c dry heat penetrates more slowly -typically: 171*C for 1 hr or 160*C for 2 hrs |
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| ultimate means of sterilization |
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| incineration. |
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| refrigeration |
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| -decreases microbial metabolism, growth, and reproduction because chemical reactions occur more slowly at low temperatures -halts the growth of most pathogens, which are predominantly mesophiles ->exceptions: Listeria and Yersinia |
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| slow freezing |
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| -ice crystals have time to form and puncture cell membranes -more effective than quick freezing in inhibiting microbial growth |
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| freezing for storage |
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| -liquid water unavailable at subzero temperatures -many bacteria and viruses are stored in low temperature freezers at -30*C to -80*C -able to reconstitute the microbes into viable populations by warming them in media containing proper nutrients |
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| dessication |
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| -aka drying -inhibits microbial growth because metabolism requires liquid water |
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| lyophilization |
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| technique combining freezing and drying, to preserve microbes and other cells for many years |
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| filtration |
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| the passage of fluid (either liquid or gas)through a sieve designed to trap particles-ie, cells or viruses-and separate them from fluid |
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| membrane filters |
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| -thin (0.1 mm) circles of nitrocellulose or plastic containing specific pore sizes, some small enough to trap viruses -pore size: 0.22 micrometers typically used in labs, sometimes 0.45 micrometers -smallest pore size 0.01 for smallest viruses -healthcare and labs usually use filtration to prevent airborne contamination of microbes |
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| HEPA filters |
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| ->high-efficiency particulate air filters -crucial parts of biological safety cabinets -also mounted into the air ducts of some operating rooms, rooms occupied by airborne diseases, and rooms of immunocompromised patients |
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| osmotic pressure |
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| -the pressure exerted across a selectively permeable membrane by the solutes in a solution on one side of the membrane -the osmotic pressure exerted by high-salt or high-sugar solutions can be used to inhibit microbial growth in certain foods -cells in a hypertonic solution lose water and the cell dessicates -fungi are resistant |
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| particulate radiation |
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| the release of high-speed subatomic particles, such as protons |
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| electromagnetic radiation |
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| -waves of electromagnetic energy from atoms -energy without mass traveling in waves at the speed of light |
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| wavelength |
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| -the distance between two crests of a wave -ranges from very short gamma rays, through X rays, ultraviolet light, and visible light, to long infrared rays, and to very long radio waves -the shorter the wavelength of an electromagnetic wave, the more energy it carries, and thus is more damaging to cells |
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| ionizing radiation |
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| -wavelengths shorter than 1 nm -sufficient energy to eject electrons from atoms, creating ions -includes electron beams, gamma rays, X rays |
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| electron beams |
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| -produced by cathode ray machines -highly energetic and therefore very effective in killing microbes in just a few seconds -cannot sterilize thick objects or objects covered with large amounts of organic matter |
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| gamma rays |
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| -emitted by some radioactive elements such as radioactive cobalt -penetrate much farther than electron beams but require hours to kill microbes |
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| gamma irradiation |
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| -FDA approved gamma irradiation for microbial control in meats, spices, fresh fruits and vegetables -kills not only microbes, but also larvae and eggs of insects. also kills the cells of fruits and vegetables preventing spoilage or over-ripening *many fast foods are irradiated |
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| nonionizing radiation |
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| -electromagnetic radiation with a wavelength greater than 1 nm does not have enough energy to force electrons out of orbit -only UV light has sufficient enough energy to be an antimicrobial agent |
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| ultraviolet light |
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| -nonionizing radiation/antimicrobial agent -UV light with 260 nm is specifically absorbed by adjacent pyrimidine nucleotide bases in DNA, causing them to form covalent bonds with each other rather than hydrogen bonds with bases in the complementary DNA strand (=pyrimidine dimers) -UV light does not penetrate well |
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| pyrimidine dimers |
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| -covalent bonds formed between adjacent pyrimidine nucleotide bases in DNA, rather than hydrogen bonds with bases of the complimentary DNA strand -occurs with adjacent C, T, or U -most commonly thymine -distorts the shape of DNA, making it nearly impossible for a cell to transcribe or replicate its genetic material |
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| biosafety levels |
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| CDC established guidelines for four levels of safety in microbiological laboratories dealing with pathogens |
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| BSL-1 |
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| Biosafety Level 1: -suitable for handling microbes not known to cause disease in healthy humans, ie: E. coli -precautions are minimal and include hand washing with antimicrobial soap and washing surfaces with disinfectants |
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| BSL-2 |
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| Biosafety Level 2: -similar to BSL-1 but designed for handling moderately hazardous agents -ie: hepatitis, influenza, MRSA -access to lab is limited when work is being conducted, extreme precautions with contaminated sharp objects, procedures with possible aerosols conducted in safety cabinets |
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| BSL-3 |
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| Biosafety Level 3: -stricter. requiring that all manipulations be done with HEPA safety cabinets and specifying special design features for the lab -double set of doors with ventilation, air leaving room through HEPA-filters -ie: tuberculosis, anthrax bacteria, viruses of yellow fever and Rocky Mountain spotted fever |
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| BSL-4 |
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| Biosafety Level 4: -most secure laboratories -designated for dangerous or exotic microbes that cause severe or fatal diseases in humans -ie: Ebola, smallpox, and Lassa fever viruses -these labs are either isolated building or completely separated from all other areas of their buildings -entry and exit are strictly controlled through electronically sealed airlocks with multiple showers, vacuum room, UV light room, and other safety precautions -all air and water entering or leaving facility is filtered -personnel wears "space suits" supplied with air hoses |
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| chemical methods of microbial control |
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| -more commonly used than physical methods -chemical agents tend to destroy or inhibit the growth of enveloped viruses, vegetative cells of bacteria, fungi and protozoa more than fungal spores, protozoan cysts, or bacterial endospores -includes: phenols, alcohols, halogens, oxidizing agents, surfactants, heavy metals, aldehydes, gaseous agents, and enzymes |
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| phenolics |
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| -in 1867, Dr. Joseph Lister began using phenols to reduce infection during surgery -compounds that have been derived from phenol molecules that have been chemically modified by the addition of halogens or other organic functional groups -intermediate to low level disinfectants -denature proteins and disrupt cell membranes in large variety of pathogens -commonly used in healthcare settings, laboratories, and households -disagreeable odor and possible side effects |
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| bisphenolics |
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| -composed of two covalently linked phenolics -examples: orthophenylphenol = active ingredient in Lysol; triclosan = incorporated into numerous consumer products such as garbage bags, diapers, cutting boards |
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| hexachlorophene |
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| once a popular household bisphenolic, found to cause brain damage in infants |
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| alcohols |
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| -bactericidal, fungicidal, and virucidal against enveloped viruses -not effective against fungal spores or bacterial endospores -considered intermediate level disinfectants -denature proteins and disrupt cytoplasmic membranes (note that denaturation of protein requires water) -solutions of 70%-90% alcohol are typically used to kill microbes -commonly used: rubbing alcohol (isopropanol) and drinking alcohol (ethanol) |
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| isopropanol |
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| -rubbing alcohol -slightly superior to ethanol as a disinfectant and antiseptic |
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| tinctures |
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| solutions of other antimicrobial chemicals in alcohol and are more effective than the same chemicals dissolved in water |
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| halogens |
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| -the four very reactive, nonmetallic chemical elements: iodine, chlorine, bromine, and fluorine -intermediate level antimicrobial chemicals -effective against vegetative bacterial and fungal cells, fungal spores, some bacterial endospores, and many viruses -unfold and denature essential proteins including enzymes |
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| iodine |
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| -well known antiseptic -protozoan cysts survive water tx -used as either a tincture or iodophor (ie: Betadine) |
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| iodophor |
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| -an iodine-containing organic compound that slowly releases iodine -long lasting and non-irritating to the skin -ie, Betadine: used for surgery prep, prior to injections, and for burns |
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| chlorine |
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| -elemental form of chlorine: used for to treat drinking water, swimming pools, and waste water -compounds containing chlorine: sodium hypochlorite (household chlorine bleach), and calcium hypochlorite.. used for disinfection of utensils or dialysis systems |
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| emergency drinking water |
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| -2 drops of household bleach added to a liter of water for an emergency -does not kill protozoan cysts, bacterial endospores, or viruses |
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| chlorine dioxide |
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| -a gas that can be used to disinfect large spaces -used in the federal buildings contaminated with anthrax spores following the 2001 bioterrorism attack |
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| chloramines |
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| -chemical combinations of chlorine and ammonia -used in wound dressings, as skin antiseptics, and in some municipal water supplies -less effective antimicrobial agents than other forms of chlorine, but they release chlorine slowly and thus are longer lasting |
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| bromine |
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| -an effective disinfectant in hot tubs because it evaporates more slowly than chlorine at high temperatures -used as an alternative to chlorine in swimming pools, cooling towers, and other water containers |
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| fluorine |
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| -the form of fluoride is antibacterial in drinking water and toothpastes -can help reduce the incidence of dental caries -disrupts the metabolism in the biofilm of dental plaque |
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| oxidizing agents |
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| -kill microbes by oxidizing their enzymes, thereby preventing metabolism -high level disinfectants and antiseptics that work by releasing oxygen radicals (especially effective for anaerobic microorganisms) -ie: peroxide, ozone, and peracetic acid -used in deep puncture wounds |
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| hydrogen peroxide |
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| -common household chemical that can disinfect and even sterilize the surfaces of inanimate objects -not a good antiseptic for open wounds because catalase neutralizes the hydrogen peroxide into oxygen and water -hot hydrogen peroxide used by food processors to sterilize packages like juice boxes |
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| ozone |
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| -reactive form of oxygen generated when molecular oxygen 02 is subjected to electrical discharge -ozone is what gives the fresh air smell after thunderstorms -Canadian and European municipalities treat their water with ozone instead of chlorine. better antimicrobial agent, but more expensive. |
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| peracetic acid |
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| -extremely effective sporicide that can be used to sterilize surfaces -used by food processors and medical personnel -it is not adversely effected by organic contaminants and does not leave behind any toxic residue |
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| surfactants |
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| -"surface active" chemicals -reduces the surface tension of solvents such as water by decreasing the attraction among molecules -reduction of surface tension results in the solvent becoming more effective at dissolving solute molecules -low level disinfectants -include: soaps, detergents, and quats |
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| soap |
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| -by themselves are good degerming surfactant, but poor antimicrobial agents -when household soaps are antiseptic, it is because they contain antimicrobial chemicals |
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| synthetic detergents |
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| -positively charged organic surfactants that are more soluble in water than soaps -most popular detergents for microbial control= quaternary ammonia compounds (aka quats) |
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| quats |
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| -quaternary ammonia compounds -composed of an ammonium cation, in which the hydrogen atoms are replaced by other functional groups or hydrocarbon chains -colorless, tasteless, and harmless to humans -ideal for many medical and industrial applications -ie: benzalkonium chloride (Zephiran) and cetylpyridinium chloride (Cepacol mouthwash) -function by disrupting cellular membranes, so that cells lose essential ions such as potassium ions -bactericidal (Gm+), fungicidal, virucidal (enveloped viruses) -some pathogens thrive in quats= low level disinfectant |
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| heavy metals |
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| -heavy metal ions combine with sulfur atoms in molecules of cysteine, an amino acid. such bonding denatures proteins, inhibiting or eliminating their function -low level bacteriostatic and fungistatic agents -includes: arsenic, zinc, mercury, silver, and copper -ie: 1% silver nitrate, thimerosal, copper |
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| 1% silver nitrate |
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| -previously used in the eyes of newborns to prevent blindness caused by N. gonorrhoeae -silver still plays an antimicrobial role in surgical dressings, burn creams, and catheters |
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| thimerosal |
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| -example of a heavy metal -mercury containing compound to preserve vaccines |
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| copper |
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| -interferes with chlorophyll -used to control algal growth in reservoirs, fish tanks, swimming pools, and water storage tanks -effective algicide in concentrations as low as 1 ppm -blue solution added to ponds |
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| aldehydes |
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| -compounds containing terminal -CHO groups -function in microbial control by cross-linking (forming covalent bonds between) amino, hydroxyl, sulfhydryl, and carboxyl organic functional groups; which denatures proteins and inactivates nucleic acids -includes: glutaraldehyde, formaldehyde, and formalin |
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| glutaraldehyde |
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| -liquid -highly reactive chemical -2% sol'n kills bacteria, fungi, and viruses -disinfects in 10 minutes, sterilizes in 10 hours -less irritating and more effective than formaldehyde, but more expensive |
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| formalin |
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| -example of an aldehyde -37% solution of formaldehyde dissolved in water -used by morticians and health care workers for embalming, disinfection of isolation rooms, exhaust cabinets, surgical instruments, and reusable kidney dialysis machines |
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| formaldehyde |
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| -must be handled with care b/c it disrupts mucous membranes and is a carcinogen -typically diluted in water to form a 37% sol'n called formalin |
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| cross-linking |
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| -formation of covalent bonds (that shouldn't be there) -aldehydes cross-link functional groups such as amino, hydroxyl, sulfhydryl, and carboxyl groups in order to denature proteins and inactivate nucleic acids |
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| gaseous agents |
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| -highly reactive microbicidal and sporicidal gases used within closed chambers to sterilize -over time, functions by denaturing and DNA by cross-linking organic functional groups -penetrates paper and plastic wraps and diffuse into every crack -high level/sterilization -includes: ethylene oxide, propylene oxide, beta-propiolactone -must be used in very controlled environments (toxic) |
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| ethylene oxide |
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| frequently used as a gaseous sterilizing agent in hospitals and dental offices and NASA uses this to sterilize spacecraft designed to land on other planets |
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| enzymes |
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| -antimicrobial enzymes:many fungi produce chemicals that inhibit or destroy a variety of bacteria, fungi, and viruses -include: lysozyme, Prionzyme |
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| lysozyme |
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| -contained in human tears -a protein that digests the peptidoglycan cell wall of bacteria, causing the cell wall to rupture because of osmotic pressure in the eye -used by food processors to reduce the number of bacteria in cheese |
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| Prionzyme |
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| -removes prions from medical instruments -first noncaustic chemical to target prions -approved in 2006 by the European Union |
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| antimicrobials |
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| -includes: abx, semisynthetics, and synthetics -typically used for the tx of disease, not for environmental control of microbes -some for use outside the body; ie, nisin and natamycin (for cheese) |
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| antibiotics |
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| -form of antimicrobials -chemicals made by one type of organism that inhibits or kills another (ie: pcn, fungi that kills bacteria) -"in other words": antimicrobials produced naturally by microorganisms |
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| semi-synthetic |
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| -form of antimicrobials -chemically modifying an abx or other natural chemical |
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| synthetics |
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| -form of antimicrobials -designed chemicals created in a laboratory |
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| nisin and natamycin |
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| -forms of antimicrobials -used outside of the body -reduces the growth of bacteria and fungi in cheese |
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| resistant microbes |
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| -little evidence that extensive use of antiseptics and disinfectants adds to human or animal health -extensive use does promote the development of resistant microbes -while susceptible cells die, resistant cells remain to proliferate |
