Term
Sterilization: Physical Agents (Moist Heat) |
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Definition
Physical Agents -
Moist heat – uses an autoclave that introduces steam under pressure
-Most effective, practical method
-Most hospitals use it as a first choice method of sterilization
-Not applicable to heat-labile substances (ie., antibody solution, antibiotics)
-The steam must be able to penetrate in order to sterilize the material (container cannot be sealed; petroleum jellies not penetrated)
-Inactivates life forms by denaturation/coagulation of biological molecules; steam is the killing agent
-Process sterilizes more quickly than dry heat |
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Term
Sterilization: Physical Agents (Dry Heat) |
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Definition
Dry heat
-Inactivates life forms by oxidation/denaturation
-Does not dull sharp edges, unlike autoclaving
-Can sterilize closed containers and oils/petroleum jellies, which are not penetrated with steam
-Takes longer to sterilize than autoclaving
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Term
Sterilization: Ultraviolet Radiation |
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Definition
-Radiation
Ultraviolet radiation
-Damages DNA & inhibits its replication
-Most effective against airborne microorganisms
-Often used to prevent airborne spread of bacteria in hospitals, microbiology labs, etc.
-Poor penetration |
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Term
Sterilization: Ionizing Radiation |
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Definition
Ionizing radiation
-Beta rays (electron) or gamma rays
‘Chain reaction’ where bacterial/viral cell components absorb electrons, then give off high energy electrons, disrupting cell components
- Sutures, plastic tubing, plasticware |
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Term
Sterilization: Filtration |
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Definition
-Filtration
-Used for solutions that are heat labile or whose efficacy/safety is compromised by the introduction of chemicals or heat (i.e., antibiotics/antibody solutions)
-Solution is filtered through a membrane that retains bacteria, fungi, algae
-Does not always remove viruses (depends on pore size – for example 0.2 micron filter will not remove some viruses) – therefore not ‘sterilization’ in the strictest sense (Not FDA-approved sterilization method) |
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Term
Sterilization: Chemical Agents |
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Definition
Ethylene oxide (gas, slow) alkylates
-Useful for delicate instruments, optics
-Flammable, explosive and carcinogenic so use has been curtailed
Glutaraldehyde (liquid solution, 2%) alkylates Inhibited by dirt
Hydrogen peroxide solution (>10%) or plasma – oxidizes
Plasma: hydrogen peroxide plasma that has been microwaved to increase available oxygen radicals, which are the killing agent
Chlorine dioxide –gas (used to decontaminate buildings where anthrax attacks occurred); oxidizes
Peracetic acid (liquid solution) oxidizes
-Preferred method of sterilizing heat-sensitive instruments at LSUHSC.
-By products are non-toxic (acetic acid and oxygen) |
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Term
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Definition
‘Critical Items’ – items that enter tissue, blood; example: surgical items, cardiac catheters, implants
-Items that would be dangerous if contaminated with spores
-ALWAYS sterilize! Any life forms present a high degree of risk
‘Semicritical items’ – items that come into contact with mucous membranes; example: endoscopes
-Items that do not present such a high risk if contaminated by a small amount of spores but should not be contaminated with bacteria/viruses
Sterilize OR use high level disinfectant
Noncritical items – blood pressure cuffs, crutches, bed rails, floors
-May come in contact with intact patient skin
-Low or medium level disinfection
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Term
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Definition
High level: (used mostly on semicritical items; some overlap with sterilants; all high level methods may be sporocidal)
-Glutaraldehyde (2%) – liquid - Alkylates cell components. BURNS!
-Peracetic acid (0.2%) – liquid - Oxidizes cell components
-Chlorine dioxide – Oxidizes, liquid or gas (also a sterilant) TOXIC!
-Hydrogen peroxide (>10%) – liquid or plasma - Oxidizes cell components |
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Term
Disinfection: Intermediate Level |
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Definition
Intermediate level (used mostly on noncritical items; either weakly sporocidal or nonsporocidal)
-Alcohols – denature proteins – inhibited by dirt! Some used as antiseptic.
-Sodium Hypochlorite (bleach) – inhibited by alkaline pH (i.e. alkaline detergents). Stronger bacteriocidal/virucidal/sporacidal activity at higher concentrations (can be high or low level disinfectant)
-Iodophor compounds – denature/oxidize proteins – not influenced by pH – inhibited by dirt. Some used as antiseptic. |
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Term
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Definition
Low level – noncritical items (not sporicidal; do not inactivate all bacteria/viruses)
Quaternary ammonium compounds – denature cell membranes; precipitate biological molecules. |
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Term
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Definition
Chlorhexidine: surgical scrub, medicated soap, mouthwash
-Disrupts membranes/lipids
- Activity persists after drying
- Poor killing activity against some Enterocococcus,
Staphylococcus species. |
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Term
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Definition
• Most common ingredient in antibacterial soaps, other common antibacterial products (soaps, deodorants, toothpaste, socks!)
• Inhibits a specific bacterial enzyme: bacterial enoyl-acyl carrier protein reductase enzyme.
• Effects on virus unknown!
• Bacterial resistance? Though effective in laboratory settings, efficacy in households/clinical settings uncertain. |
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Term
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Definition
Alcohol gels: best choice for routine hand antisepsis.
-Fast acting
-Broad spectrum killing
-Increased compliance over handwashing!
-Use has decreased NI!
-Hands need to be free of dirt before using!
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