Sterilization, Disinfection, and Antisepsis Flashcards
What are routes for transmission during dental treatment?
Direct contact with infectious lesions, saliva, or blood
Indirect transmission via contaminated intermediate object
Spatter of blood, saliva, plaque, or nasopharyngeal secretions
Aerosolization of blood, saliva, plaque, or nasopharyngeal secretions
Ebola
50% fatality rate - greater age means higher rate
Symptoms: fever, headache, muscle pain, vomiting, diarrhea, stomach pain, bruising or bleeding
Highly infectious
Transmited by direct contact with body fluids of infected person
Killed by disinfecting agents
Incubation period 2-12 days
Not contagious until symptoms develop
HIV
Risk of transmission from healthcare worker to patient is very low
No documented cases of occupationally acquired infection
Standard infection control practices are highly effective
Risk from precutaneous exposure 3 or 4 per 1000 exposures
Immediate post-exposure retroviral therapy is effective
Hep B
300,000 persons infected every year
Many documented cases from and to health care workers
Vaccination
Tuberculosis
Risk of transmission during dental procedures appears to be low
Epidemic resurgence
Coughing produces aerosols
Not transmitted by surface contamination
Herpes
Herpes simplex I and II are frequently present in the oral cavity
May be transmitted to/from healthcare worker
What immunizations are recommended for healthcare providers by the CDC?
Hep B Influenza Measles Mumps Rubella Varicella zoster
Critical
Items come into contact with tissue or the vascular system (eg surgical instruments)
Semi-critical
Items come into contact with mucous membranes or non-intact skin (eg curing light)
Noncritical
Items touch intact skin (eg blood pressure cufF)
Sterilization
Destruction or removal of all forms of life (including spores)
Can be heat or chemical
Not used on humans (only inanimate objects)
What does the FDA mandate regarding sterilization
Liquid chemical sterilants used on critical and semicritical devises and gaseous sterilants
Disinfectants
Inhibition or destruction of pathogens
Spores are not killed
Regulated by both the FDA and EPA
What does the EPA mandate regarding disinfection?
Disinfectants used on noncritical surfaces
Antiseptics
Formulated to destroy pathogenic microorganisms on living tissues
Safe for use on human tissues
Regulated by the FDA
T/F - Antiseptics and disinfectants can be used interchangeably
False
High level disinfection
Destroys all microorganisms with the exception of spores
Intermediate-level disinfection
Inactivates M. tuberculosis, vegetative bacteria, most viruses, and most fungi
Does not necessarily kill bacterial spores
Low-level disinfection
Kills most bacteria, some viruses, and some fungi
Cannot be relied on to kill resistant microorganisms such as M. tuberculosis or bacterial spores
How do you clean Critical items?
Sterilization
Hoe do you disinfect Semicritical items?
High or intermediate-level disinfection is required
Sterilize if you can
How do you clean non-critical items?
Low-level disinfectants are sufficient
Why must items be cleaned off before sterilization?
Bioburdn may prevent sterilization
What is the most commonly used method of steam sterilization?
Autoclave
What are the autoclave conditions?
Steam under pressure 121' C (250' F) 15 psi 15-20 minutes Packaging material must allow for penetration of steam (paper, plastic and cloth ok; not closed metals or glass containers)
What are the advantages of an autoclave?
Short cycle time
Good penetration
What are the disadvantages of an autoclave
Corrosion (oxidaiton) of unprotected carbon steel and dulling of cutting agents (may be prevented with 1% sodium nitrite solution)
Deposits from hard water (use distilled)
May remain wet at the end of cycle
Destruction of heat sensitive materials
What are the conditions of Statim brand Flash steam sterilization
Rapid cycle
134’ C (273’ F)
30 psi
6-12 minutes
What is the major factor of sterilization
Denaturing vital proteins
Why is more time required for dry heat sterilization?
Dehydrated proteins are more stable, so higher temperature for longer is required
What are the conditions for dry heat sterilization?
160’ C (320’ F) for 2 hours
170’ C (340’ F) for 1 hour
Packaging material must allow transfer of heat - paper, plastic, aluminum
What are the advantages of dry heat sterilization?
Does not corrode or dull cutting edge
What are the disadvantages of dry heat sterilization?
Long cycle
May discolor or char fabric
Destroys heat sensitive materials (rubber, plastic, soldered impression trays)
Unsuitable for handpiecesq
Rapid heat transfer sterilization conditions
190’ C (375’ F)
12 minutes for wrapped items
6 minutes for unwrapped items
Rapid heat transfer sterilization advantages
Short cycle
Dry at the end
Does not corrode or dull
What are the disadvantages of rapid heat transfer sterilization?
Instruments must be dry to start
Destruction of heat labile items
Not suitable for handpieces
Unwrapped items not protected after cycle
Unsaturated chemical vapor sterilization
“Chemiclave”
Depends on heat, water, and chemical synergy
Mixing of methyl alcohol, formaldehyde, ketone, acetone, and water used to produce sterilizing vapor
Penetration isn’t as good as steam, so items must be loosely packaged and dry
Unsaturated chemical vapor conditions
131’ C (270’ F)
20 psi
20-40 minutes
Packaging material must allow for penetration of vapor (no closed metal or glass containers)
What are the advantages of unsaturated chemical vapor sterilization
Short cycle time
Does not corrode or dull cutting edge
What are the disadvantages of unsaturated chemical vapor sterilization?
Chemical odor and safety concerns
Instruments must be dry before use
Chemical solution required
Heat-sensitive material can get destroyed
T/F - autoclave tapes indicate that items have been sterilized
False - they only indicated that they have been through the autoclave cycle
They do not ensure adequacy of sterilization cycle
What are the best garuntee of sterilization
Biological indicators
How do biological monitors work?
They contain spores that are more resistant than viruses or vegetative forms of bacteria
B. stearothermophilus (autoclaves and chemiclaves)
B. subtilis (dry heat)
What are the two forms of biological monitors
Glass vials containing suspensions of spores plus a pH indicator - if spores germinate and produce acid, we can see a color change
Spore-impregnated strips in glassine envelopes that must be sent to service for checking
T/F - Chemical sterilants can be used instead of heat
False - only use when heat is inappropriate
Ethylene oxide (ETO)
Alkylating agent - irreversibly inactivates nucleic acids and proteins
Used as sterilization of heat and moisture sensitive items
CDC and ADA recognize as acceptable
Will burn tissue
Ethylene oxide sterilization cnditions
Room temperature (25’ C / 75’ F)
10-16 hours
Package in paper or plastic
Ethylene oxide advantages
Does not damage heat or moisture labile materials
Does not leave a residue after adequate aeration
Ethylene oxide disadvantages
Slow Hazardous chemical Items must be clean and dry beforehand Retained in liquids and rubber items for long time Toxic residue if not well aerated
Glutaraldehydes
Glutaraldehyde 2-3.2% solution
Effective against vegetative bacteria, including M. tuberculosis, fungi, viruses, and spores
EPA registered as chemical stimulant
Inactivates proteins
Glutaraldehyde sterilization conditions
Room temperature
10 hours
Immersed in solution
Glutaraldehyde sterilizaiton advantages
Most potent chemical germicide
Active in presence of organic debris
Glutaraldehyde sterilizaiton disadvantages
Long immersion interval rinsing required Severe tissue irritation and toxicity from fumes Allergenic Biologically non-verifiable Cannot package items Corrosive to metals
Quaternary ammonium-alcohol combination disinfectant (CaviWipes)
Combo of alcohol and quaternary ammonium solution
Intermediate level disinfectant for semicritical items
What are the advantages of Quaternary ammonium-alcohol combination disinfectant?
Low odor
Less toxic/irritating than phenolic compounds
Accelerated Hydrogen Peroxide Disinfectants
Combo of 0.5% hydrogen peroxide, chelating agents, and wetting agents
Intermediate level disinfectant
Packaged as wipe or spray
Accelerated Hydrogen Peroxide Disinfectants advantages?
No odor
Non-toxic
Short contact time
Cleans and disinfects
Iodine and Iodophors
Good handwashing antiseptic
Iodinates proteins
Biocidal in 5-10 minutes
Chlorine-containing compounds
Primary antimicrobioal activity by oxidaiton as hypochlorous acid
Rapidly causes unfolding and aggregation of proteins
Chlorine-containing compound advantages
EPA registered High level disinfetant Rapid action Broad spectrum Economical
Chlorine-containing compound disadvantages
Unpleasant, persistent odor (swimming pool)
Irritating to skin, eyes
corrosive
Damages clothes
Degrades plastics and rubber
Chemically unstable - must be made fresh daily
T/F - Gloves are a perfect barrier
False
T/F - Alcohol-based hand rubs are the most efficacious agents for reducing the number of bacteria on teh hands of personnel
True
When is soap and water handwashing indicated?
Visibly soiled hands
Hand hygiene technique with alcohol rub
20-30 seconds
Dispense full pump of hand rub
Rub covering all surfaces until completely dry
Hand hygiene technique with soap and water
Wet hands
Apply soap
Wash all surfaces including thumb and fingertips
Use disposable towels
Dry hands completely before donning gloves
Do not touch contaminated taps or waste cans after washing
