Lecture 6 Flashcards Preview

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Flashcards in Lecture 6 Deck (80):
1

Sterilization

absolute removal or destruction of all microbial life and viruses. all microorganisms are limited (including endospores)

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Disinfection

destruction of pathogenic microorganisms, kills most but not all microbes, destroys pathogens on inanimate objects

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Example of disinfectants

alcohol and bleach

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Antisepsis

disinfection (destroys pathogens) of living tissue, rears less harsh of a chemical treatment

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Degerming

removal of most microbes from limited area

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Example of degerming

swabbing of small area of skin w/ alcohol mechanical removal

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Sanitization

lowering the microbial counts on a surface such that they are at a safe level

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Bacteriocidal

agent that kills bacteria

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Bacteriostatic

agent that stops the bacteria from reproducing

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Asepsis (aseptic)

area is free of significant contamination

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Example of aseptic

modern surgical technique,in order to minimize infection from operating personnel, instruments and patient

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Heat as a physical method of microbial control

kills microbes by destroying their fundamental enzymes, when heat applied its irreversible, bacteriocidal

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3 types of heat as a physical method of microbial control

-dry heat
-moist heat
-pasteurization

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Boiling as physical method of microbial control

moist heat, disputes protein structure by breaking H bonds, accomplishes disinfection

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Boiling for 5 min kills

-most pathogens
-most viruses
-but NOT endospores

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Autoclave as physical method of control

moist heat, combines 15psi of pressure and 121C of steam, kills all endospores in 15 min,, used for culture media and hospital instruments

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Best method for sterilization

autoclave

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Pasteurization as physical method of microbial control

eliminates pathogens and reduces microbial counts in order to slow spoilage (doesn't result in sterilization) mild heating of liqui

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Classic treatment of pasteurization

63C for 30 minutes

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HTST pasteurization

high temp short time, 72C for 15 seconds, most common!!!*

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UHT pasteurization

ultra high temp, 140C for 3 seconds, can be store w/o refrigeration

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Dry heat sterilization kills via

oxidation

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Direct flame as physical method of microbial control

used in microbio lab to sterilize inoculation needles/loops. metallic instruments must be red hot in order to be considered sterile

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Incineration as physical method of microbial control

effective way to sterilize and dispose of contaminated material (dressings)

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Hot air sterilization as physical method of microbial control

drying over, material should be kept at 170C for 2 hours to ensure sterilization, used for dry materials that aren't temp sensitive (glassware)

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Filtration as physical methods of microbial control

vacuum is used to force liquid through a filter w. very small pores (0.10-0.45μm) pores are too small for bacteria to pass through used to sterilizes temp sensitive liquids

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Filtration is used to sterilize..

temp sensitive liquids such as antibiotics, enzymes, vaccines, culture media

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Con to filtration

viruses are much smaller than bacteria and able to pass through pores

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Air filration as physical method of microbial control

high efficiency particulate air (HEPA) filters air, used in some operating rooms to remove all microbes larger than 0.30μm in diameter

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Low temperature as physical method of microbial control

refrigeration, slows/stops microbial growth. bacteriostatic, freezing stops microbial growth (only small portion of microbes die)

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High pressure as physical method of microbial control

liquid suspensions are treated w. high pressure as it disturbs protein/molecular structure. bacteriocidal, doesn't kill endospores

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Desiccation as physical method of microbial control

used to control (slow/stop) microbial growth, bacteriostatic, removal of water (drying)

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Osmotic pressure as physical method of microbial control

high concentrations of salt/sugar create hypertonic environment, bacterial cell will dehydrate and shrivel. old/yeast more resistant

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Osmotic pressure is both ...

bacteriocidal and bacteriostatic

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Radiation as physical methods of microbial control

destroys DNA. X rays and gamma rays penetrate materials, UV and high NRG electron beams are used on surfaces

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Microwaves as physical methods of microbial control

use longer wavelengths so not high enough to kill organism directly, it heats water which kills microorganisms, can disinfect material

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Most chemical methods of microbial control can be used to ...

disinfect but may not be used to achieve sterilization

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1st step of disk diffusion method

disk of filter paper is soaked in chemical disinfectant

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2nd step of disk diffusion method

disk is placed on agar plate that already been inoculated with bacteria

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3rd step of disk diffusion method

chemical will diffuse from paper to plate

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4th step of disk diffusion method

plate is incubated until inoculated bacteria grow

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5th step of disk diffusion method

zone of clearance around the bacteria is used to determine the effectiveness of disinfectant

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Phenolics and biphenols

disinfectant, disrupt plasma membrane and denature porteins, bacteriocidal, very effective and remain active long after, mixed with other compounds in order to decrease toxicity,

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Example of phenolics

lysol for household disinfection

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Example of biphonals

hexachlorophene and triclosan

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Hexachlorophene

useful against bacteria that cause skin infections in newborns, so used in nurseries. caution cause may cause neurological disorders

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Triclosan

used in some personal hygiene and cosmetics (deodorant)

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Biguanides / chlorhexidine

attacks plasma membrane, used to control microbes on skin and mucous membrane, bacteriocidal, can persist for 6 hrs, only kills enveloped viruses

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Microorganisms that are resistant to chlorhexidine

non enveloped viruses, endospores, mycobacteria

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Chlorhexidine is used in what for surgeons

hand soap

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Halogens

impair protein synthesis and alter membranes, used as household bleach and iodine for antiseptic

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Chlorine as antiseptic

used as gas or combined /w other chemical, strong oxidizing agent that destroys enzymes

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Idoine as antiseptic

one of oldest/most effective antibiotics, available as either incur or iodophore

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Tincture

solution in aqueous alcohol

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Iodophore

combination of iodine and organic molecule, iodine is slowly released from origin molecule

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Example of iodine

betadine (used as antiseptic for skin)

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Alcohols

denature proteins and disrupt lipid membranes, kill bacteria and fungi, not means of sterilization, acts quick w/ no residue

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Alcohol is not a good..

antiseptic when applied to wounds (harmful)

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Two types of alcohol most commonly used

-ethanol (70% most effective)
-isopropanol (rubbing alcohol)

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Heavy metals as disinfectants and antiseptics

metals such as copper, silver, zinc, and mercury can inhibit microbes

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Silver nitrate

(1%) is used as antiseptic, in eyedrops for newborns to protects against gonorrhoea of the eye

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Silver sulfadiazine

combination of silver and sulfadiazine drug used as topic cream for burns

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Silver ions can also be incorporated into..

dressings/catherters to prevent hospital acquired infections

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Copper flute can be used to destroy..

green algae that lives in swimming pools/fish tanks

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Zinc chloride has been used in..

mouth washes

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Soaps and detergents

do not work at antiseptic, most important in mechanical removal of microbes

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Soap breaks up...

oil present on skin and water washes it away

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Soap and water are good ...

degerming agents

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Quaternary ammonium compounds (quats)

cationic detergents that kill most bacteria fungi and some viruses, less effective on gram - than gram +. effect the plasma membrane

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Quats are strongly...

antimicrobial, colorless, tasteless, odourless, and non toxic at low concentrations

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What grows and survives in quats

pseudomonas

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Gaseous chemosterilizers

chemical gases used for sterilization

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Example of gaseous chemosterilizers

ethylene oxide

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Ethylene oxide

bacteriocidal, kills all microbes (including endospores) requires 4-18 hrs exposure, highly penetrating (pass thru plastic)

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Ethylene oxide can be used to sterilize ..

disposable hospital equipment and lab supplies

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Oxidizing agents

oxidize (remove electrons from structure) and denature proteins. useful against anaerobe organisms

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3 examples of oxidizing agents

-hydrogen peroxide
-ozone
-benzol peroxide

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Hydrogen peroxide

common antiseptic for wounds

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Ozone

used w/ chlorine to disinfect water

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Benzol peroxide

used as antiseptic on skin, kills bacteria on living tissue