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90 Cards in this Set
- Front
- Back
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Process of destroying all microbial life on an object
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Sterilization
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Process of reducing or inhibiting microbial growth on a nonliving surface
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Disinfection
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Process of reducing or inhibiting microorganisms on living tissue
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Antisepsis
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Suffix -cide means what?
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Kill
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Suffix -stat
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Inhibit
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What is the term for bacterial contamination?
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Sepsis
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What is the term that refers to gram (-) bacteria in the blood stream
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Sepsis
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Curve in which it shows the amount of death of bacterial populations
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Death curve
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On the death curve, what will show as a constant death?
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Straight line
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Time to kill a microbial population is proportional to what?
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Number of microbes present
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Which of the 2, vegetative form or endospores, are more susceptible to physical and chemical controls?
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Vegetative
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What can interfere with heat treatments and chemical control agents?
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Organic matter
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True or false:
Longer exposure to lower temps = the same lethal effect as shorter time at higher temps |
True
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What are 2 ways that a microbial control agent can kill/inhibit growth?
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1. Damaging the plasma membrane by altering its' permeability
2. Damage proteins and nucleic acids |
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What are 5 physical methods of controlling microbial growth?
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1. Temperature (low&high)
2. Filtration 3. Desiccation 4. Osmotic pressure 5. Radiation |
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What is used to denature enzymes/proteins?
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Moist heat
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What does TDP stand for?
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Thermal death point
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Term in which the lowest temperature that all bacteria in a liquid culture will be killed in 10 min.
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Thermal death point (TDP)
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Different methods that produce the same reduction in microbial growth are called what?
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Equivalent treatments
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Term that explains the length of time required to kill all bacteria in a liquid culture at a given temperature
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Thermal death time (TDT)
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What does TDT stand for?
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Thermal death time
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What does DRT stand for and what is another term for it?
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Decimal reduction time aka D value
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Term used to describe the time a certain temperature to reduce a microbial population by 90% (or 10 fold or by one log).
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Decimal reduction time (DRT) aka D value
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At what temp kills many vegetative cells and viruses within 10 min?
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Boiling point (100 C)
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Most effective method of moist heat sterilization.
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Autoclaving
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At what temperature is autoclaving typically at?
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121 C
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What 3 components consist of autoclaving?
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Heat
Steam Pressure |
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Dry heat kills by what?
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Oxidation
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What are 3 methods of dry heat sterilization?
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Flaming, incineration, and hot-air sterilization
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What temperature and term is used to "sterilize" dairy products?
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Ultra high temperature "UHT" - 140C for 3 sec
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Whats more effective in controlling microbial growth in terms of temp vs. time: dry heat or moist heat sterilization?
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Moist heat
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Type of sterilization in which a passage of a liquid or gas through a filter with pores small enough to retain microbes.
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Filtration
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How can microbes be removed from the air?
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Air filters
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What are membrane filters composed of?
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Nitrocellulose or cellulose acetate
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What 2 factors influence the effectiveness of low temperature microbial growth?
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Particular microorganism and intensity of application
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Most microbes cannot reproduce at this temperature (without denaturing the enzymes) and can potentially die.
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Refrigerator temperature or below (subzero)
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What is used to preserve bacterial strains in research laboratories?
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Liquids nitrogen
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Term used that describes the removal of a water source or moisture to kill microbes.
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Desiccation
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What and which can resist desiccation?
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Viruses
Endospores Salmonella |
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The use of high or low concentrational environments to cause death.
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Osmotic pressure
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Microbes can undergo what when presented with high concentrations of salt or sugars?
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Plasmolysis
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What are more capable of surviving/growing in environments with low moisture or high osmotic pressure?
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Molds and yeasts
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Effects of radiation depend on what 3 factors?
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Wavelength
Intensity Duration |
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What are 3 types of radiation?
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Ionizing radiation
Ultraviolet radiation Microwaves |
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Type of radiation that uses gamma rays, X rays, and high-energy electron beams
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Ionizing radiation
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Radiation that is also known as nonionizing radiation
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Ultraviolet radiation
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Type of radiation that ionizes water and forms highly reactive hydroxyl radicals
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Ionizing radiation
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Type of radiation that is high energy & contains a high degree of penetration.
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Ionizing radiation
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Type of radiation that has a low degree of penetration
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Ultraviolet radiation
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What is the most effective ultraviolet germicidal wavelenght?
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260nm
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True or false:
Microwaves can kill bacteria directly |
False - microwaves can kill bacteria indirectly by the heating of materials.
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What are resistant to microwaves?
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Bacterial spores
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Term used to describe chemical agents that are used on living tissure
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Antiseptics
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Term used to describe chmical agents that are used on inanimate objects
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Disinfectants
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Test to see the survival rate of bacteria when exposed to a certain disinfectant
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Use-dilution test
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The lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation
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Minimum inhibitory concentration (MIC)
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Method of evaluating the effectiveness of disinfectants by placing a disk filter paper, soaked with chemicals and placed on an inoculated agar plate.
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Disk-diffusion method
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What is shown for effectiveness on the agar plate (around the paper) with the disk-diffusion method?
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Clear zone
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What are 3 types of disinfectants?
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Phenol
Bisphenols Biguanides |
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Type of disinfectant that exert their action by injuring plasma membranes.
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Phenol
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Type of disinfectant that are used widely as household products
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Bisphenols
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Type of disinfectant that damages plasma membranes of vegetative cells.
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Biguanides
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What 2 halogens are used as disinfectants?
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Iodine
Chlorine |
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Term used to describe something that is in a solution with alcohol.
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Tincture
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Term used to describe something that is combined with an organic molecule.
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Iodophor
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Type of disinfectant that exerts their action by denaturing proteins and dissolving lipds
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Alcohols
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Heavy metals combine with what to denature proteins?
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Sulfhydryl (-SH) groups
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Term that decreases the tension between molecules that lie on the surface of a liquid
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Surface-active agents
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What are examples of surface tension agents?
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Soaps
Detergents |
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__________ have limited germicidal action but assist in the removal of microorganisms through scrubbing
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Soaps
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Used to clean dairy equipment
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Acid-anionic detergents
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What does Quat stand for?
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Quaternary ammonium compounds
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Quats are what type of detergents?
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Cationic detergents
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Quats are effective against what type of bacteria?
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Gram (+)
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What inhibits fungal metabolism?
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Food preservatives:
-SO2 -sorbic acid -benzoic acid -propionic acid |
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What prevents the germination of Clostridium botulinum?
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Nitrate or nitrate salts
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What bacteria do nitrate salts prevent from germinating?
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Clostridium botulinum
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What type of antibiotics are used to preserve food; especially cheese
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Nisin
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Type of chemical disinfectant that exert their antimicrobial effect by inactivating proteins
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Aldehydes
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What are 2 forms of antimicrobial aldehyde?
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Formaldehyde
Glutaraldehyde |
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What gas is used most frequently for sterilization?
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Ethylene oxide
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Type of gas that penetrates most material and kill all microbes by protein denaturing
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Ethylene oxide
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What are 3 types of peroxygens?
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Ozone
Peroxide Peracetic acid |
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A type of oxidizing agent that exert their effect by oxidizing the molecules inside cells
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Peroxygens
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Which are more resistant to microbial control: gram (+) or gram (-) ?
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Gram (-)
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These microbes are highly resistant to disinfectants
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Mycobacteria
Endospores Protozoan cysts |
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What type of viruses are generally more resistant to disinfectants and antiseptics?
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Nonenveloped viruses
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Incorrectly folded proteins are referred to as what?
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Prions
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BSE or mad cow disease are examples of what?
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Prions
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A host protein that is able to convert normal molecules of protein into abnormal structured proteins.
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Prions
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