Microbiology Chapter 9 Study – Flashcards
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the removal or destruction of ALL microbes, including viruses and bacterial endospores, in or on an object
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Sterilization
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describes an environment or procedure that is free of contamination
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Aseptic
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the use of physical or chemical agents known as________, including ultraviolet light, heat, alcohol, and bleach, to inhibit or destroy microorganisms, especially pathogens
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Disinfection
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when a chemical is used on skin or other tissue, and the chemical is called an __________.
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Antisepsis, Antiseptic
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the removal of microbes from the surface by scrubbing, such as when you wash your hands or a nurse prepares an area of skin for an injection
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Degerming
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the 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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Sanitization
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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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Pasteurization
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refer to agents that destroy or permanently inactivate a particular type of microbe
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-cide/-cidal
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indicating inhibition but not complete destruction of a type of microbe
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-stasis/-static
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regulate cellular metabolism, function as enzymes in most metabolic reactions, and form structural components in membranes and cytoplasms
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Proteins
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an enzymatic RNA molecule
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Ribozyme
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kill all pathogens, including bacterial endospores. used to sterilize invasive instruments such as catheters, implants, and parts of heart-lung machines
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High-level germicides
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kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria but not bacterial endospores. Used to disinfect instruments that come in contact with mucus membranes but are noninvasive, such as respiratory equipment and endoscopes.
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Intermediate-level germicides
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eliminate vegetative bacteria, fungi, protozoa, and some viruses. Used to disinfect items that contact only the skin of patients, such as furniture and electrodes
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Low-level germicides
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permanent loss of reproductive ability under ideal environmental conditions
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Microbial Death
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minimal and include hand washing with antibacterial soap and washing surfaces with disinfectants; suitable for handling microbes such as E. coli
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Biosafety Level 1 (BSL-1)
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Designed for handling moderately hazardous agents, such as hepatitis and influenza viruses; extreme precautions are taken with contaminated sharp objects, and procedures that might produce aerosols are conducted within safety cabinets
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BSL-2
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requiring all manipulations be done within safety cabinets containing high-effeciency particulate air (HEPA) filters, entry through double sets of doors; experimentation on microbes such as tuberculosis and anthrax and viruses of yellow fever and Rocky Mountain spotted fever
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BSL-3
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Most secure labs, designated for working with dangerous or exotic microbes that cause severe or fatal diseases in humans, Ebola, smallpox, Lassa fever viruses; normally in separate buildings or completely isolated from all other areas of their buildings, entry and exit are strictly controlled through electronically sealed airlocks with multiple showers, vacuum room, ultraviolet light room, etc. Personnel have to wear "space suits"
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BSL-4
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the lowest temperature that kills all cells in a broth in 10 minutes
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Thermal Death Point
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the time it takes to completely sterilize a particular volume of liquid at a set temperature
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Thermal Death Time
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the time required to destroy 90% of microbes in a sample
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Decimal Reduction Time (D)
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commonly used to disinfect, sanitize, sterilize, and pasteurize; kills cells by denaturing proteins and destroying cytoplasmic membranes
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Moist Heat
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First method considered for controlling microbes using moist heat; kills vegetative cells of bacteria and fungi, the trophozoites of protozoa, and most viruses within 10 minutes at sea level
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Boiling
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true sterilization using heat, requires higher temperatures than that of boiling water
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Autoclaving
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consists of a pressure chamber, pipes to introduce and evacuate steam, valves to remove air and control pressure, and pressure and temperature gauges to monitor the procedure
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Autoclave
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milk pasteurized for 30 minutes at 63 degrees C
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Batch method
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milk flows through heated tubes that raise its temperatures to 72 degrees C for only 15 seconds
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Flash pasteurization
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Heats milk to at least 135 degrees C for only 1 second
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High-temperature pasteurization
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passing milk/liquids through superheated steam at about 140 degrees C for 1 to 3 seconds then cooling rapidly
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Ultra-high-temperature pasteurization
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sterilization using an oven, or Bunsen burner
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Dry Heat
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drying, used to preserve fruit, peas, beans, grain, nuts, and yeast; inhibits microbial growth because metabolism requires liquid water
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Desiccation
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technique combining freezing and drink to preserve microbes and other cells for many years
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Lypophilization
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process in which water is transformed directly from a solid to a gas
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Sublimation
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the passage of a fluid (either a liquid or a gas) through a sieve designed to trap particles (cells or viruses) and separate them from the fluid
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Filtration
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consists of high speed subatomic particles, such as protons, that have been freed from their atoms
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Particulate radiation
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energy without mass traveling in waves at speed of light, released from atoms that have undergone internal changes
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Electromagnetic radiation
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electron beams, gamma rays, and some X-rays (wavelengths shorter than 1 nm), when they strike molecules they have sufficient energy to eject electrons from atoms, creating ions
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Ionizing 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
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Nonionizing radiation
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-Heat-Related Methods (moist heat, autoclaving, boiling, Pasteurization, Ultra-High-Temp. Sterilization, Dry Heat) -Refrigeration and Freezing -Desiccation and Lypohilization -Filtration -Osmotic Pressure -Radiation (Ionizing radiation, Nonionizing radiation)
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Physical Methods of Microbial Control
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-Phenols -Alcohols -Halogens -Oxidizing Agents -Surfactants -Heavy Metals -Aldehydes -Gaseous Agents -Enzymes
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9 Major Categories of antimicrobial chemicals used as antiseptics and disinfectants
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compounds derived from phenol molecules that have been chemically modified by the addition of halogens or organic functional groups
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Phenolics
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composed of two covalently linked phenolics
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Bisphenolics
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bactericidal, fungicidal, and virucidal against enveloped viruses; however, they are not effective against fungal spores or bacterial endospores -considered intermediate-level disinfectants
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Alcohols
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Four very reactive, nonmetallic chemical elements: iodine, chlorine, fluorine, and bromine -intermediate-level antimicrobial chemicals -effective against vegetative bacterial and fungal cells, fungal spores, some bacterial endospores and protozoan cysts, and many viruses
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Halogens
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Well-known Antiseptic -used in medical institutions to prepare for surgery and injections and to treat burns
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Iodine (Betadine)
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-used to treat drinking water, swimming pools, and waste water from sewage treatment plants
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Chlorine
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-effective disinfectant in hot tubes because it evaporates more slowly than chlorine at high temperatures -used as an alternative to chlorine in disinfecting swimming pools, cooling towers, and other water containers
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Bromine
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-antibacterial in drinking water and tooth paste, can help reduce the incidence of dental caries (cavities)
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Fluorine
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-High-level disinfectants and antiseptics that work by releasing oxygen radicals, which are particularly effective against anaerobic microorganisms
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Oxidizing Agents
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common household chemical that can disinfect and even sterilize the surfaces of inanimate objects such as contact lenses, but is often mistakenly used to treat open wounds
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Hydrogen Peroxide (H2O2)
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reactive form of oxygen that is generated when molecular oxygen (O2) is subjected to electrical discharge
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Ozone (O3)
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extremely effective sporicide that can be used to sterilize surfaces
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Peracetic Acid
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"surface active" chemicals -2 most common are soaps and detergents
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Surfactants
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positively charged organic surfactants that are more soluble in water than soaps
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Synthetic Detergents
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most popular detergents for microbial control, composed of an ammonium cation (NH4+) in which the hydrogen atoms are replaced by other functional groups or hydrocarbon chains -bactericidal (particularly against Gram-Positive bacteria), fungicidal, and virucidal against enveloped viruses, but not effective against non enveloped viruses, mycobacteria or endospores
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Quaternary Ammonium Compounds (Quats)
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arsenic, zinc, mercury, silver, and copper are antimicrobial because they combine with sulfur atoms in molecules of cysteine, an amino acid -low-level bacteriostatic and fungistatic agents
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Heavy-metal ions
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compounds containing terminal CHO groups -Glutaraldehyde- a liquid -Formaldehyde- is a gas Function in microbial control by cross-linking amino, hydroxyl, sulfhydryl, and carboxyl organic functional groups
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Aldehydes
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act against microorganisms
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Antimicrobial Enzymes
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brain, spinal cord, placenta, eye, liver, kidney, pituitary gland, spleen, lung, lymph nodes, and cerebral spinal fluid
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Places in the body that can harbor prions
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antibiotics, semi synthetics, and synthetics
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Antimicrobials
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antimicrobial chemicals produced naturally by microorganisms
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Antibiotics
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when scientists chemically modify an antibiotic
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Semisynthetic
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-Phenol and Phenolics -Alcohols -Halogens -Oxidizing Agents -Surfactants -Heavy Metals -Aldehydes -Gaseous Agents -Enzymes -Antimicrobials
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Chemical Methods of Microbial Control
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Ethylene Oxide, Propylene Oxide, Beta-propiolactone
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Gaseous Agents
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A ratio that compares a given agent's ability to control microbes to that of phenol under standardized conditions
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Phenol coefficient
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In this test a researcher dips several metal cylinders into broth cultures of bacteria and briefly dries then at 37 degrees C, then immerses each contaminated cylinder into a different dilution of the disinfectants being evaluated, after 10 minutes each cylinder is removed, rinsed with water to remove excess chemical and placed into a fresh tube of sterile medium for 48 hours of incubation
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Use-Dilution Test
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A standard alternative assessment approved by the European Union to determine the capacity of a given chemical to inhibit bacterial growth
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Kelsey-Sykes Capacity Test
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A more realistic (though more time-consuming) method for determining the efficiency of a chemical
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In-Use Test
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Phenol Coefficient, Use-Dilution Test, Kelsey-Sykes Capacity Test, In-Use Test
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Methods for Evaluating Disinfectants and Antiseptics
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Ethylene oxide
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Which antimicrobial chemical has been used to sterilize spacecraft?
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A pressure cooker
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Which of the following times functions most like an autoclave?
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Aseptic
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Which of the following adjectives best describes a surgical procedure that is free of microbial contaminants?
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Ethylene oxide
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Which of the following chemicals is active against bacterial endospores?
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DNA
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UV light kills cells because it damages which of the following?
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Bacillus Stearothermophilus
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The endospores of which organism are used as a biological indicator of sterilization?
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Protect cells from toxic forms of oxygen
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The function of a catalase is to ____________?
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An ideal antimicrobial agent is stable during storage, an ideal antimicrobial agent is fast acting, and ideal microbial agents do not exist
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Which of the following statements is true concerning the selection of an antimicrobial agent?
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The hydroxyl radical
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Which of the following is the most reactive and toxic form of oxygen?
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Sterilization eliminates organisms and their spores or endospores
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In practical terms in everyday use, which of the following statements provides the definition of sterilization?
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In-Use test
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A company that manufactures an antimicrobial cleaner for kitchen counters claims that its product is effective when used in a 50% water solution. By what means might scientists best verify this statement?
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Decimal reduction time
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A sample E. coli has been subjected to heat for a specified time, and 90% of the cells have been destroyed. Which of the following terms best describes this event?
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Hydrogen peroxide
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Which of the following substances is least toxic to humans?
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double set of entry doors, pressurized suits, and showers in entryways
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Biosafety Level 3 includes _______?
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Quaternary ammonium compounds
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Which class of surfactant is most soluble in water?
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Proteins
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Enzymes are usually which type of molecule?
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the efficiency of a detergent, the efficiency of an antiseptic, and the efficiency of sanitization techniques
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The microbial death rate is used to measure __________?
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Sanitization
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Which of the following terms best describes that disinfecting of cafeteria plates?
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Desiccation
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The preservation of beef jerky from microbial growth relies on which method of microbial control?
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Pasteur
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Which of the following scientists invented a method for killing only the harmful microbes in a substance such as fruit juice or milk?
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Phenol
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Which of the following disinfectants acts against cell membranes?
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Disinfectants
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Which of the following substances or processes kills microorganisms on laboratory surfaces?
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Electron beams
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Which of the following types of radiation is more widely used as an antimicrobial technique?
