Term
| importance of controlling the growth of microorganisms |
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Definition
-prevention and transmission of infectious diseases
-prevention of non-desirable microorganisms
-prevention of material, equipment by microorganisms |
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Term
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Definition
destruction or removal of all forms of microbial life including endospores (except prions)
-usually done by steam under pressure or sterilizing gas |
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Term
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Definition
| -sufficient heat treatment to kill endospores of Clostridium botulinum in canned food |
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Term
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Definition
| -destruction of vegetative pathogens |
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Term
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Definition
| destruction of vegetative pathogens on living tissue |
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Term
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Definition
| removal of microbes from a limited area such as skin around injection site |
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Term
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Definition
| treatment intended to lower microbial counts on eating and drinking utensils |
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Term
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Definition
| -agent that kills microorganisms |
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Term
| bactericide/fungicide/virucide |
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Definition
| kills bacteria /fungi/ virus |
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Term
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Definition
| agent that inhibits the growth or multiplication of bacteria |
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Term
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Definition
| object/area free of pathogens |
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Term
| Decimal reduction time (d-value) |
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Definition
| -length of time it takes an agent to kill 90% of the population |
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Term
| effectiveness of antimicrobial treatment factors |
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Definition
-number of microorganisms
-presence of organic matter (inhibits action of chemical agents)
-temp (better in warm)
-presence of proteins and fat (protects microorganisms)
-overall fitness of the cell
-time of exposure |
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Term
| modes of action of antimicrobial agents |
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Definition
-damage cell wall (lysozyme)
-damage plasma membrane (alter permeability)
-alteration of proteins (break hydrogen and covalent bonds)(denature and enzyme inactivation)
-alteration of nucleic acids (compounds that prevent synthesis of bases or polymerization)(no more replication=no more proteins) |
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Term
| 3 types of antimicrobial agents |
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Definition
-physical
-chemical
-antibiotics |
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Term
| physical antimicrobial agents |
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Definition
-heat
-cold
-dessication
-osmotic pressure
-radiation
-filtration |
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Term
| types of heat antimicrobial agents |
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Definition
-moist heat sterilization
-dry heat sterilization |
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Term
| heat kills microorganisms by |
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Definition
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Term
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Definition
-thermal death point
-lowest temp where all microorganisms in a liquid are killed in 10 min |
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Term
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Definition
-thermal death time
-minimum length of time it takes to kill all bacteria in a liquid at given temp |
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Term
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Definition
-decimal reduction time
-length of time it takes an agent to kill 90% of the population (1 log unit) |
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Term
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Definition
-works by denaturing proteins (coagulation)
-most efficient method
-boiling water kills bacteria vegetative forms, most viruses, fungi (and their spores) in about 10 min(does not kill bacterial spores)
-tyndallization
-pressurized steam
-pasteurization
-ultra high temp |
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Term
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Definition
-consists of boiling a substance for 3 days in a row
-on second day most spores that survived would have germinated
-these would be killed after the second day of heating
-third day kills bacterial cells from late germinating spores
-not used often today but used for things that cant withstand pressure |
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Term
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Definition
-allows to reach temp higher than boiling water
-an autoclave is used to sterilize 121 deg cel under 15 psi
-most efficient
-fast
-excellent penetration
-abundant moisture
-can be used for liq/solid |
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Term
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Definition
-uses mild heating sufficient to eliminate pathogens that cause food spoilage
-important to kill Mycobacterium tuberculosis and Coxiella burnetii
-milk is pasteurized by heating at 62 deg cel for 30 min |
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Term
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Definition
-treatment that consists of heating milk or juice at 140 deg cel for 2-4 seconds followed by rapid cooling in a vacuum chamber
-liquid is sprayed through a nozzle into a chambered containing high temp steam
-allows to store milk/juice for months at room temp |
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Term
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Definition
-coagulates proteins
-causes oxidative free radical damage
-flaming is simplest way
-incineration is useful to sanitize medical and biohazardous wastes before it is discarded with non hazardous waste
-hot air sterilization items placed in oven and heated at
160 deg cel for 2 hours (glassware, pipettes, oils, powders) |
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Term
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Definition
-slows growth by slowing metabolic rate of microorganisms
-preserve bacterial strain for long term storage |
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Term
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Definition
-removal of water from microorganisms
-microorganisms cannot grow or reproduce
-remain viable for years
-growth resumes when rehydrated
-lyophilization is a type that allows freeze drying under a vacuum |
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Term
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Definition
-high salt or sugar concentrations create hypertonic conditions
-cause water to exit cell = death |
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Term
| most bacteria cannot grow in salt conc between |
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Definition
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Term
| sugar concentration that is inhibitory |
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Definition
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Term
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Definition
-ionizing/nonionizing radiation
-gamma and x rays
-high energy electron beams |
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Term
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Definition
-act by ionizing water inside the cell
-form highly reactive hydroxyl radicals that react and alter DNA |
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Term
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Definition
| have short wavelengths that penetrate deep but act slowly |
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Term
| high energy electron beams |
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Definition
| have lower penetrating power but act quickly |
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Term
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Definition
-UV light
-longer wavelength(greater than 1 nm)than ionizing
-not very penetrating
-most efficient around 260nm
-cause damage to DNA by thymine dimer formation and inhibit replication |
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Term
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Definition
-used to sterilize thermolabile substances(culture media, enzymes, vaccines, antibiotics)
-filters contain tiny pores
-HEPA(high efficiency particulate air) used in hospital research .3uM
-membrane filters made of cellulose esters, plastic polymers, dont retain viruses(.22uM ,45uM) |
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