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sterilization and disinfection
n/a
43
Microbiology
Undergraduate 3
02/02/2013

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Term
control of infectious disease agents
Definition
1. public sanitation
2. sterilization and disinfection procedures
3. chemotherapeutic agents (antibiotics)
4. bodies defense mechanisms
Term
sterilization
Definition
total destruction of all microbes
Term
disinfection
Definition
destruction of most pathogenic microbes
-remaining are nonpathogens and spores of pathogens
Term
bacteriocidal
Definition
agent that kills bacteria
Term
bacteriostatic
Definition
agent that inhibits bacterial growth
Term
antiseptic
Definition
chemicals with low human toxicity that destroy mcroorganisms capable of caughing contamination or disease
Term
factors affecting sterilization/disinfection action
Definition
1.time
2.temp
3.ph
4. # of microorganisms
5. types of microorganisms
6.presence of extraneous matter
7.proper exposure
8. concentration of disinfectand or sterilant
Term
methods of physical control
Definition
1. heat-high temps inactivate proteins and nucleic acids by breaking their hydrogen bonds
2. radiation-causes chemical changes to the nitrogenous bases of nucleic acids
3. filtration-physical removal of organisms from the solution that is filtered
Term
heat
Definition
-most widely used method for microbial control
-decimal reduction time or D value--measures on organisms heat resistance
Term
heat sensitive tape
Definition
tape impregnated with chemicals that change color when exposed to a critical temperature
Term
biological monitor
Definition
spore strips of clostridium or bacillus
Term
heat treatment procedures
Definition
dry heat
moist heat
boiling water
pasteurization --flash pasteurization
Term
dry heat
Definition
generated by an oven
condition: 160 celcius, 2 hrs--kills spores
usage: sterilization of lab glassware
disadvantage- high temp, chars organic materials
Term
moist heat
Definition
generated by an autoclave (industrial pressure cooker)
condition: 121 degrees celsius. 15 min, 15 lb/in^2 --kills spores
usage: sterilization of microbiological media, glassware and ommercial canning
disadantage: expensive equipment
Term
boiling h20
Definition
water bath or chamber
condition- 100 celcius for 30 min-kills all non spore forming microorganisms
usage: hospitals-disinfect bedding/clothing of patients
home-boil unsafe drinking water, disinfect baby items
disadvantage-items easily recontaminated when removed from h20
Term
pateurization
Definition
process of using mild heat to kill pathogens while preserving the quality and flavor of food
condition-62-66 celcius, 30 min, quick cool (time and temp conditions required to kill coxiella burnetti)
usage-destruction of pathogens in milk, beer and wine----increases shelf life
Term
flash pasteurization
Definition
newer technique
condition- 71.7 celsius, 15s, quick cool
Term
radiation
Definition
emission and propagation of energy thru space or thru a substance in the form of waves

a. uv light-non ionizing (100-400 nm wavelength)
b. ionizing radiation
Term
bacteriocidal wavelength
Definition
25-=270nm
dna absorbs uv light which induces a rearrangment in hydrogen bonding of the dna strant. these changes result in copying errors which increase the probability of a lethal mutation
Term
germicidal lamp (mercury vapor lamp)
Definition
-generates radiation at 254nm
usage: disinfection rather than sterilization lamps are placed in air ducts or directly over surface. uv lamps are placed in air supply ducts of operating rooms, food preperation areas, nursing homes and nurseries
-effectveness: reduces the concentration of air-borne microbes by 99%
-disadvantage: limited use since uv light is absorbed by solids-damaging to human tissues (skin and eye) - sunburn, wrinkles, cancer and retinal damage
Term
ionizing radiation
Definition
-shorter wavelength that uv, increased energy, energy in absorbed by atoms --> ions (gain/loss of electrons) ionization---> forms primarily free hydroxyl radicals which react with cellular proteins and nucleic acids, inducing chemical alterations that are cidal
usage: sterilizing medical products, tissues, bone, skin, meat, fruit, veggies
-advantages: speed, high penetration power-ability to penetrate fabrics, plastics, liquids and foods for sterilization
disadvantage- radiation exposure
Term
filtration
Definition
sterilization for removing microbes but not destroying them
Term
filter membrane
Definition
cellulose acetate, polycarbonate, variety of plastics (teflon or nylon)
0.22 micromete pore size removes all bacteria
0.025 micromete pore size removes all viruses
Term
liquid filtration
Definition
-used to sterilize liquids that cannot withstand heat (serum, blood products, vaccines, antibiotics, iv fluids, enzymes)
water purification
Term
air filtration
Definition
HEPA used in air ducts to critically clean areas
Term
HEPA filter
Definition
high efficiency particulate air filters
-tightly woven fiberglass medium which remove particles as small as 0.3 micrometers with 99.9% efficiency
-usage HEPA filters are installed in air supply systems to operating rooms, nurseries, ICUs and biohazard hoods
Term
alcohols
Definition
ethyl alcohol and isopropyl alcohol effective antiseptics when applied as 70-80% aqueous solutions
-mode of action: alcohols precipitate proteins and solubiliza lipids present in the cell walls and cell membranes of bacteria
usage: human skin antiseptic
effectiveness: kills vegetative cells but not sporicidal
Term
halogens
Definition
iodine
idophors
chlorine
Term
iodine
Definition
effective antiseptic when solubilized in 70% ethyl alcohol (tincture)
mode of action: inactivates proteins and organic molecules by reacting w hydroxyl groups
usage-human skin antiseptic, treating cuts and abrasions
Term
idophors
Definition
iodines complexed with soap
-usage: preoperative skin disinfectant
-advantage: soluble in h20 and gradually releases iodine
-disadvantage: not as effective as tincture
Term
chlorine
Definition
reacts with h20 to from HC10-strong oxidant
-oxidizes sulfhydral groups of cell proteins
-clorox-contains 5.25% sodium hypochorite
usage: sanitize toilets,dishes, food processing equipments
Term
formaldehyde and glutaraldehyde
Definition
same mechanism to kill microbes
mode of action- both alkylating agents subsitite alkyl groups for the h atoms of reactive groups of enzymes, nucleic acides and proteins.

-formaldehyde: gaseous state, usage: fumigant, disadvantage: noxious vapos, irritate tissues
Term
formaldehude sol'n
Definition
formalin
usage: tissue fixative,inactivator of vaccines, embalming fluid
disadvantage: tissue irritant
Term
glutaraldehyde sol'n
Definition
usage: effective cold sterilizing agent - primary use is sterilization of dental equipment
disadvantage: irritates tissues, mildly disagreeable odor
Term
copper, mercury and silver
Definition
heavy metals toxicity is due to their ability to combine with active chemical (sulfhydral) groups on proteins
Term
copper sulfate
Definition
usage: algaecide, additive to marine bottom paints- inhibits attachment of mussels and barnacles
Term
mercurials
Definition
mercury containing compounds
usage: additive to ointments and sol'ns used in the topical treatment of skin infections
disadvangve: toxicity, allergic rxns, and neutralization by organic matter
Term
silver nitrate
Definition
usage: 1% soln of silver nitrate used as eye drops for newborn infants to prevent infections by gonorrhoeae
Term
silver sulfadiazine
Definition
additive to ointments used to prevent infections in burn patients
Term
ethylene oxide
Definition
bactericidal, fungicidal and sporicidal (12 hours, 70 celsius kills spores)
usage-sterilizing agents for plastics
advantage-ability to sterilize at moderate temps with no moisture
Term
quaternary ammonium compounds (quats)
Definition
bacteriocidal for a wide range of vegetative bacteria
-mode of action- kills cells by disrupting their cytoplasmic membrane
-usage-disinfect floors, walls, etc (also used for prepping vagina and other sensitive mucous membrane structures for surgery)
-advantage-odorless, colorless, tasteless, inexpensive, non-toxic to mammalian tissue, soluble in water and active in low concentrations
-disadvantages-readly inactivated by organic or inorganic substances
Term
phenols
Definition
lower toxicity phenolics are effective disinfectants, non-sporicidal
-mode of actions-denature proteins, and disrupt cell membranes
-advantage-reasonable cost, compatibility with detergents, resistance to inactivation by organic matter
-hexachlorophene-effectively kills staphylococci
usage-1960s as an antiseptic for bathing newborns
-disadvantage-absorption thru skin linked to brain damage in infants
-usage today: prescription only
Term
hydrogen peroxide
Definition
bactericidal or sporicidal dependent on concentration: 3-6% kills bacteria, 10-25% kills spores
-mode of action: oxidizing agent that inactivates essential protein structures
-usage: a 3% solution is used to cleanse wounds and disinfect plastic implanst, contact lenses and surgical prostheses
-advantage: non-irritating to tissues
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