8. Sterilization, Antiseptics and Disinfectants Flashcards
What is sterile?
no LIVING microorganisms are present - which is why we cannot be sterile
What is asepsis?
no PATHOGENIC organisms present - we can be surgically clean
What are the 4 categories that all things within an operating room fall into?
- Sterile - Absence of all living microorganisms including spores and pathogenic products
- Aseptic - Absence of pathogenic microorg. that cause infection
Ex. portion of a living creature can be surgically clean - Clean - Object or surface disinfected and not knowingly exposed to any pathogens, achieved by chemical disinfectant and scrubbing motion (mechanical)
- Contaminated - an object, animate or intimate, that is known to harbor pathogens - ex floor shoes pus and suspected infections
What is aseptic technique
all steps takent o prevent contam of sx site by infectious agents - properly sterilizing sx equipment, cleaning operating room, scrubbing and draping
risk doubles every house under GA
What are the two sources of microorganisms routes?
Exogenous route: Air, sx supplies, patients skin, sx team
Endogenous route: bacteremia: through the bloodstream
What is the surgical procedure designation of clean, clean-contaminated, contaminated and dirty
Clean: no break in asepsis during sx, the GI, resp and urinary tracts are not entered
Clean-contaminated: a contam area such as genitals, urinary or resp tract has been entered with no spread of contents
Contaminated: no infection present but spillage of viscera contents
Dirty: major break in asepsis. Sx that is infected or contaminated
Define sterilize
complete destruction or removal of all microorganisms and their pathogenic products
define disinfect
destruction or removal of vegetative pathogens but not bacterial endospores. usually referring to an inanimate object
Define disinfect
chemical applied to inanimate objects to destroy or inhibit vegetative pathogens. Chemicals typically too harsh to use on living tissue
define antiseptic
chemical applied to body surface to destroy or inhib vegetative pathogens
What is sterilization, how does it work?
process of destroying all microorgs. AND their pathogenic products (endotoxin and exotoxin)
Does nOT refer to prions (abnormal proteins) and may not destroy all plasmids
Used to maintain asepsis; both o prevent contam and to destroy contams
items then considered sterile
What are the 4 main methods of sterilization
sterilization by heat (moist heat or dry heat)
Chemical sterilization
ultra-filtration
ionizing radiation
What is steam sterilization
sterilization by moist heat
Item subjected to moist heat, at a predetermined temp, pressure, length of time
microbes destroyed by coagulation of protein, damages nucleic acids, destroys spores and prions
What is autoclaving?
placing steam under very high pressure to inc the temp to approx 120C
Pressure does not inc the killing effect but causes more heat to be required for water to boil
typical pressures in an autoclave are 20 psi (pounds per square inch)
What are the components of an autoclave?
airtight door w/ bolting mechanism to hold in pressure
metal chamber for holding materials to be autoclaved
Steam source and steam exhaust
pressure and temp gaugesH
How long does it take for an object to be sterilized w/ an autoclave. What can we use in it?
20m
can use sterilized liquids, wrapped and unwrapped materials
What are some precautions when autoclaving
pack materials loosely
Containers w/ liquids - caps MUSt be loose or bottles explode, cannot fill to top as they’ll boil over, place bottles in tray to catch spills, allow pressure @ end of cycle to release slowly or there is risk of boiling over, overexpansion or explosion
ALWAYS open door a gap (bolts still engaged) allows pressurized steam to escape from chamber as rapid release = sever burns
NEEEVVERR autoclave alcohols, bleach, acids, formalin or anything noxious or flammable
What quality controls is there for autoclaving?
autoclave tape, fusible melting pellet glass, culture tests, chemical indicators, air removal test (prevacuum sterilizers)
What is autoclave tape?
placed on outside of an autoclave pack or container
Tape changes when reached 121C
does not indicate HOW LONG it was exposed to that temp so it should not be used as the only indicator of sterility
What are steam chemical indicator strips?
strips of paper w/ a chemical pellet that melts after reaching a certain temp for a certain amount of time
As pellet melts, a dark dye wicks along the strip of paper. must reach end of strip to be accepted
strips should be placed in center of each individual pack and the center of loaded autoclave to ensure sterility
What are biological indicators?
a commercially prepared vial containing bacillus stearothermophilus spores (killed at 121 C in 12m) placed in center of an autoclave load. After autoclaving, contents of vial are cultured at 56C for up to 3 days to see if there is growth
if growth = autoclave not working, is it temp related or time related?
Used as quality assurance for the machine. Run periodically
What is flash sterilization
used when an item is req immediately
once autoclave reaches 120C the load is timed for 3 m
After, autoclave is shut off, set on rapid exhaust and drying cycle is skipped
after sterilization, allow packs to cool slowly
When are two chemical methods of sterilization
liquid - glutaraldehyde
Gas - ethylene oxide, plasma sterilization
What is ethylene oxide?
flammable, explosive, toxic
penetrates paper and plastic packaging w/o melting it - wrapped in plastic packaging, sealed
Temp vs time - 3-4 hrs @ room temp, humidity must be controlled
Quarantine in well-ventilated area for a min of 24 hrs, time can be reduced to 4 hrs in an aerator
What is plasma sterilization - hydrogen peroxide?
safer for enviro and personnel than ethylene oxide
not safe for linen, wood/paper, endoscopes, certain plastics, liquids
this method cannot penetrate walls of instruments so lumen will remain contaminated
What is aldehyde chemial sterilization?
formaldehyde and glutaraldehyde
toxic and irritating, antimicrobial
What is cold sterilization?
soaking instruments in disinfecting solutions (chlorhexidine or glutaraldehyde), used only for minor procedures or equipment that cannot tolerate other sterilization methods
must be rinsed thoroughly w/ sterile water under aseptic conditions (sterile gloves) soak at least 20 m, to be disinfected. 10 hours to be sterilized. completely immersed
How do antiseptics and disinfectants work?
- damaging the cell membranes
- Interfering w/ or damaging proteins
- Damaging DNA and/or RNA
- the strength of a disinfectant (how well it works) is measured by a value called the phenol coefficient or co-efficient of disinfectant
the higher this # the better its ability to kill microbes
What are enveloped viriuses?
steal a piece of host cell membrane went hey leave infected host cell - this envelope surrounds the virus particle
if this “envelope” is disrupted, the virus is destroyed
What are non-enveloped viruses?
do not have any phospholipids (usually smaller pieces of genetic material in protein capsule) > resistant to chemicals that damage cell membrane
include: K9 parvovirus, foot and mouth dz, feline calici virus and more
What limits the ability to kill spores and certain viruses?
chemicals work by destroying cell membranes are limited bc spores do not have cell membranes and viruses can be broadly categorized as enveloped and nonenveloped viruses
What makes an ideal disinfectant?
has a good coefficient of disinfection - good killing action @ low conc
Broad spectrum - vegetative bacteria and fungi; bacteria; endospores and fungal spores; enveloped and non-enveloped viruses
Stable - can be stored for long periods of time w/o losing effectiveness, can store @ room temp, in presence of light and air
Homogeneous - uniform in composition; every application acts the same
Soluble - in water > more effective to use (can spread, wipe, immerse)
non-toxic to animals and people
non-corrosive, non-bleaching, non staining, not flammable
works at room temp
high penetrance of biofilms and fat - phenol is very effective w/ fat; bleach is not
Detergent ability - both cleans and disinfects; ability to clean will help t penetrate fats, grime, biofilms
is not neutralized by organic material that may be present, ease of use, affordable and readily available, deodorizing
What is ethanol?
most commonly used at 70% v/v dilution
kills all vegetative cells, including mycobacterium
Does not destroy spores, kills some (not all) viruses
dissolves lipids, denatures proteins, does not damage nucleic acids
There must be contact time, so apply alcohol and allow to evaporate on own
has decreased efficacy at higher temps due to faster evaporation
ethanol is NOT effective at 95-100% due to rapid evaporation
What is the advatages of ethanol?
cuts thru fat and lipids, inepensive, readily available
can use on skin, on inanimate surfaces, for soakin > both a disinfectant and an antiseptic
comes in a hand gel format that includes surgical-strength hand cleaners (must follow manufacturer’s directions for surgical asepsis
What is the disadvantages of ethanol?
will cause cooling when applied to skin
Can be absorbed causing alcohol intoxication - especially in sm anim and pediatrics
Flammable and explosive
damages plastics and rubber
What is isopropyl alcohol
rubbing alcohol - 2-propanol
used at 70% v/v dilution
as effective as ethanol, especially if fortified w/ iodine or another disinfectant
cheaper and more easily obtainable than ethanol
What is quarternary ammonium compounds
commonly used disinfectant; contains ammonia
disrupts cell membranes and denatures proteins
range of activity - broad spectrum against bacteria, effective at destroying enveloped viruses
the older generations are not effective against non-enveloped viruses, some Pseudomonas resistance, mycobacterium, spores
What is the advantages of quarternary ammonium compounds
stable, dissolves easily in water
odorless, does not stain, not corrosive
effective in pus, blood, feces, inexpensive
What is the disadvantages of quaternary ammonium compounds
can cause slight injury to tissue
should never be mixed w/ soaps (will dec efficacy)
decreased activity in hard water
older gens req long contact times (10-20m))
What are oxidizing agents?
- hydrogen peroxid (peroxigard)
- hypoghlorites
- Potassium peroxymonosulfate (virkon)
What is hydrogen peroxide containing compounds
H2O2 are very reactive oxygen molecules that can damage cell membranes, mitochondria and other cell components
activity: broad spectrum, non-enveloped viruses, can destroy spores at very high concentrations
must be used at appropriate concentration - if conc is too low, catalase-prod bacteria may have some resistance
What are the advantages of hydrogen peroxide?
decomposes to water and O, inexpensive, easy to use aqueous solution, can be vaporized and used for “gas sterilization” - objects are placed in chamber and gassed w/ h2o2 compound, good for glass, metals, certain equipment
What are the disadvantages of hydrogen peroxide?
decomposes in the presence of light, metals, oxygen - new formulations are stable for months in storage
What are hypochlorites?
chlorine-containing agents
most common > sodium hypochlorite (bleach)
denatures protein - chlorine combines w/ water to release hypochlorous acid (HOCL), during reaction, any surrounding cysteine residues and S-S bonds are destroyed
Broad spectrum including bacteria,f ungi, spores and all types of viruses
acts within 30m; spores may take hours
What cautions do we need to be aware of when working with hypochlorites?
concentrated solutions w/ rapidly release chlorine gas
never mix w/ acid > will produce toxic chlorine gas
never combine w/ squats > will prod toxic chloramine gas
Caustic effects to skin and MM, especially @ higher conc
What is sodium hypochlorite
concentrated sodium hypochlorite is 20% w/v
household bleach is 5.25% w/v sodium hypochlorite
to use as a disinfectant, use a 10% solution of household bleach
corrosive > must be rinsed afterwards
be careful of fumes when using concentrated sodium hypochlorite - area must be well ventilated
avoid spills
What is potassium peroxymonosulfate
virkon
oxidizing agent w/ detergent action- oxidizes sulfur bonds in proteins and enzymes disrupting function of cell membrane causing rupturing of the cell wall
What is chlorhexidine gluconate?
antiseptic that is related to the quats
mild, low toxicity, rapid acting, poor absorption
Complex organic molecules that dissociates into a positively charged salt - this salt binds to and disrupts negative charges associated w/ bact cell walls, low conc- static, high conc - cidal
broad-spectrum against bact, year and some viruses - no action against spores, antiseptic of choice for MRSA
Available in range 0.05-4% - high conc: tissue damage, delayed wound healing. Intact skin withstands better than wound
1. aqueous formula - no alcohol, safe for eyes and flushing
2. contains alcohol - not safe around eyes and flushing
Can have allergic reactions (topical and systemic) avoid in ears
ex. hibitane
What is iodine?
antiseptic
broadspectrum bactericidal
used @ 2-2.5% sol
as water (aqueous) sol, or “tincture” - 2.0-2.5 iodine in 70% ethanol, more effective bc can cut through lipid
used for cleaning cuts, wounds, surgical prep
apply In single coat t skin and allow to air dry
AVOID eye contact
Do NOT allow to pool under patient on a surgery mat - will cause burns if prolonged contact w/ solu
What are iodophors?
iodine that is loosely bound to a detergent (such as providing) that releases it slowly AND cuts thru organic matter
prolonged effect after applied to skin
not irritating to the skin; but can have mild hypersensitivity and will discolor skin
providine-iodine common in LA (betadine, losan)
surgical scrubs, teat dips
