Sterilization and Disinfection Flashcards
What is disinfection? Sterilization?
DISINFECTION = reduction or destruction of most pathogenic microorganisms on inanimate objects
STERILIZATION = elimination of all microbes on an inanimate object
What is a disinfectant? Antiseptic? Sterility?
DISINFECTANT = chemical agent that reduces microbial load on inanimate objects
ANTISEPTIC = chemical agent that reduce microbial load/inhibit growth of microbes on living/animate objects
STERILITY = absence of all forms of microbial life on inanimate objects
Which words should be paired together?
- antiseptic
- disinfectant
- animate object
- inanimate object
antiseptic —> animate object
disinfectant —> inanimate object
What are some things considered low-level contamination areas in a hospital? High-level contamination areas?
LOW-LEVEL: reception desks, offices, walls, doors
HIGH-LEVL: kennels/housing, exam tables, operating tables/floors
What is the point of cleaning before disinfecting?
clears soiled objects so that the disinfectant can reach any microorganisms
(cleaning doesn’t deactivate microbes)
What 4 things should be thought about when selecting a disinfectant?
- What level of disinfection is required?
- Is it compatible to the item you want disinfected?
- Is it user friendly?
- Is it cost effective?
What are the 3 levels of sterility and disinfection? What equipment needs this kind of cleanliness?
- CRITICAL: equipment or implants entering the body, sterile tissue, cavity, or bloodstream that must be STERILE; surgical instruments, implants, suture material, and catheters
- SEMICRITICAL: equipment that comes in contact with skin or mucous membranes without penetrating body or cavity that must be cleaned and disinfected, along with terminal sterilization later; colonoscopes, endoscopes, endotracheal tubes, anesthetic equipment, vaginoscope
- NONCRITICAL: equipment that comes in contact with intact skin or mucous membranes but is not directly associated with surgery and should be disinfected but doesn’t require particular handling between patients and terminally cleaned later; laryngoscope, stethoscope, ultrasound probe, BP cuffs, ECG leads, pulse oximeters, exam tables
What are the 4 most common disinfectants and antiseptics used in veterinary medicine? How do they work against bacteria, fungi, viruses, and spores?
ISOPROPYL ALCOHOL (IPA): kills bacteria, fungi, and viruses, spores are resistant
POVIDONE-IODINE (PVI): kills bacteria (fast), fungi, viruses, and spores
CHLOROHEXIDINE GLUCONATE (CHG): kills bacteria (fast), works poorly against fungi and viruses, spores are resistant
ALCOHOL-BASED SOLUTIONS: tend to work across the board
Disinfectants and Antiseptics:
Is isopropyl alcohol a disinfectant or antiseptic? What activity does it have? How is its residual activity?
disinfectant and antiseptic
bactericidal/bacteriostatic at lower concentrations, kills many fungi and viruses
minimal - it does not last long and evaporates quickly
How does IPA compare to PVI and CHG? When is it most helpful?
less effective than both
removing excess lipids on the skin prior to surgery
Is povidone-iodine a disinfectant or antiseptic? What activity does it have? What is its residual activity?
disinfectant and antiseptic
bactericidal, fungicidal, effective against viruses, sporicidal with 15 mins of contact
minimal
What part of veterinary medicine uses a lot of PVI? What tends to lower its effectiveness?
large animal medicine
in the presence of organic material (when used on dirty patients)
What are the different concentrations of PVI used?
0.1-1% solution for wound management
5% scrub/solution for eye care
10% scrub/solution for surgical prep
Is cholorhexidine gluconate a disinfectant or antiseptic? What activity does it have? What is its residual activity like?
antiseptic
bactericidal (G+ > G-), minimal against viruses and fungi, not sporocidal
lasts longer due to keratin binding and is not inactivated by organic debris, alcohol, or soaps
What concentrations of CHG are used?
0.05% solution for wound management
4% scrub/solution for surgical prep
Are alcohol-based solutions disinfectants or antiseptics? How does it activity compare to the other solutions? How does its residual activity compare?
antiseptics
superior antimicrobial activity than PVI, CHG, or IPA alone
more than alcohol alone
How are alcohol-based solutions applied to the patient? What are 3 common types and their concentrations?
one-step, scrubless application; then dry
- ChloraPrep: 2% CHG, 70% IPA
- ACTIPREP: 83% ethanol, zinc pyrithione
- DuraPrep: PVI, 74% IPA
What is the absolute state of sterilization?
nothing is almost or “sort of” sterile, it either is or isn’t
You can _____ without _______, but you can’t…..
clean; sterilization
sterilize without thorough cleaning
How is steam sterilization done?
within a cylindrical machine, saturated steam destroys microorganisms by coagulation and cellular protein denaturation
What are the 5 pros to steam sterilization? 3 cons?
PROS: cheap; non-toxic, safe, and simple; effective; can be used for wrapped and unwrapped items; quick turnaround time
CONS: not suitable for heat sensitive items; potential for injury if not maintained properly; requires care and maintenance
What is gravity displacement sterilization?
type of steam sterilization reliant on the heaviness of steam compared to air, which pushes steam from the outer chamber into the inner one
Microbial death in steam sterilization is dependent on what 3 things?
- exposure time (10-30 mins)
- temperature (250-275 degrees F)
- pressure (15-18 PSI)
What is a prevacuum steam sterilizer best used for? How long are objects kept inside?
allows for the sterilization of harder-to-reach spaces and porous items through a vacuum mechanism; gowns and towels
3-4 mins at 270-275 degrees F
When are flash steam sterilizers used? How does it work? How does the type of item affect time it should be sterilized?
in emergencies when no alternative is available due to a higher contamination rate
gravity displacement sterilization using a metal tray
metal, nonporous items (without a lumen) - 3 mins
metal, porous items, rubber, plastic, power tools - 10 mins
(all at 270-275 degrees F)
What 4 situations tend to lead to a failure in steam sterilization?
- inappropriate packing or loading
- poor steam quality, leading to wet packs
- vacuum failure
- inadequate temperature
What gas is used in chemical sterilization? How does this process work?
ethylene oxide (EtO)
gas diffuses over packs and disrupts the metabolism of microbes
What are 2 pros to chemical sterilization? 3 cons?
PROS: sterilizes heat-sensitive equipment; sterilizes moisture-sensitive equipment
CONS: expensive; lengthy cycle allowing for aeration; hazardous (toxic, flammable gas)
The efficacy of chemical sterilization is dependent on what 4 characteristics?
- gas concentration
- temperature
- humidity
- exposure time
What compound is used in plasma sterilization? How does this work?
hydrogen peroxide (H2O2)
UV photons cause the production of free radicals, killing microorganisms by oxidation
What are the 3 pros to using plasma sterilization? 3 cons?
PROS: sterilizes heat and moisture intolerant items; quick turnaround time (low temp = no aeration); no harmful emissions
CONS: gas cannot penetrate linen, gauze, wood, endoscopes, plastics, liquids or powders; specific synthetic packaging needed; chamber tends to be smaller
What is the number one option for sterilization of heat and moisture intolerant items?
plasma sterilization
What wavelengths are used in ionizing radiation? Why is this type of sterilization only recommended for one-use items?
gamma
uses radiation, so you do not want equipment to become radioactive and injure another patient
What are 4 pros to ionizing radiation sterilization? 3 cons?
PROS: high penetrating power; rapid; low temperature useful for heat-sensitive equipment; flexibility
CONS: highly expensive, so it is mostly used commercially; dangerous; can cause breakdown of packing material or product
What are 4 pros to peracetic acid sterilization? 3 cons?
PROS: sterilizes heat-intolerant items; rapid sterilization cycle; low temperature; safer
CONS: only applicable for immersible instruments; expensive; no sterile storage (items must be immediately used)
What 3 chemicals are typically used in cold sterilization? These chemicals can typically be irritants. How can irritation be avoided when the instruments are used on patients?
- glutaraldehyde, 2%
- ortho-phthalaldehyde (OPA)
- hydrogen peroxide, 7.5%
instruments must be rinsed with sterile water and dried with sterile towels
Why is cold sterilization a good alternative? What does its effect depend on?
it is noncorrosive
contact (immersion) time
- disinfection = 10 mins
- sterilization = 10 hrs
Methods of Sterilization:
What is found in sterilization packs? How do we decide what a pack is wrapped with?
all components needed for surgery in one sterile pack (gown + towel, instruments + gauze, misc.)
method of sterilization (must be able to be penetrated)
Different packs:
When are paper bags best to use as a wrapping material? 2 pros? 3 cons?
when what’s getting sterilized is small, light, and not sharp
PROS: cheap; easily obtained
CONS: easily perforated when wet; items cannot be visualized; heavy items can break through
What are the 2 types of cloth material used for wrapping?
- linen - cotton blend (muslin, linen)
- synthetic
Describe the laminated sleeves/packs/pouches used as wrapping material? What are 4 pros? 2 cons?
combination of transparent, heat-stable plastic film laminated over treated paper
PROS: cheap and easily obtained; pre-cut sizes or rolls in various widths; several small items can fit; instruments can be identified
CONS: easily perforated when wet; heavy and pointed items can break through paper portion
What containers can be used and wrapped as a surgery pack? What are 2 major perks?
aluminum and stainless steel
- can be flash sterilized
- can store a wide variety of surgical instruments
What is the typical procedure to cleaning and sonicating instruments prior to wrapping for sterilization?
- pre-clean rinse
- instrument soak
- clean (manually; ultrasonic)
- post-clean rinse (milk)
- instrument drying while wide open
What are the 6 steps to preparing a surgical pack after cleaning them off?
- place and organize instruments
- add drape and gauze
- add sterile indicator
- wrap (2x)
- secure with autoclave tape
- sign and initial
What is the purpose of sterilization indicators? What are the 2 types?
monitor effectiveness of the sterilization process
- CHEMICAL INDICATORS: chemical change occurs in response to heat, pressure, and/or humidity, but NOT exposure time —> DOES NOT confirm sterility
- BIOLOGICAL INDICATORS: uses bacteria maintained in a broth or strip as an indication of sterility —> ONLY means of ensuring sterilization
What are 2 possible purposes of huck towels?
- use to dry hands
- used as a drape
When wrapping a pouch, in what direction should the instruments face?
in a way that the handles will face the veterinarian
