Disinfection Flashcards
Why do we disinfect?
- to get rid of unwanted pathogenic microorganisms
to eliminate or at least reduce exposure risk
- medical waste treatment
- spill cleanup
- minimization of nosocomial infections
- routine surface decontamination
to eliminate contamination risk
- preparation of microbiology media and supplies
- prep of pharmaceutical production supplies and equipment
prep of food- surface sanitization
prep of work are for cleanliness- critical tasks
What are the 5F’s?
food
fingers
flies
feces
fomites
(water, air, vehicles, transported blood and tissues)
sterilization
act or process physical or chemical that destroys or eliminates all forms of life especially microorganisms- highest level
disinfectant
an agent usually chemical that inactivates viruses or kills vegetative microbes but not nescecarily resistant forms such as spores
antiseptic
a substance that prevents or arrests the growth or action of microbes either by inhibiting their activity or by destroying them- living tissue
decontamination
disinfection or sterilization of contaminated articles to make them suitable for use
- minimizing risk of transmission/ contamination
sanitizer
an agent that reduces the number of vegetative bacteria only
- doesn’t kill everything on hands but reduces to safe number
cide
kills- determined by specific testing
bacetricide
= germicide
destroys vegetative bacteria only
sporocide
destroys bacterial spores
fungicide
destroys fungal spores
tuberculocide
destroys M. tuberculosis
virucide
destroys specific viruses
static
prohibits growth may not kill
bacetriostatic
prevents growth of veg bacteria
- but doesnt kill whats on surface
lots of antibiotics have their affect
tuberculostatic
prohibits growth of Mycobacterium tuberculosis
Resistance to disinfectants
What is the mode of action of chlorine
- saponification of fatty acids
- neutralization of amino acids
- chloramination of amino acids
Who was Ignaz Semmelweis
pioneered physician handwashing with calcium hypochlorite
chlorine
- available as liquid powder or table form
- household bleach usually 5-6% Na hypochlorite
- in use dillutions depend on application and amount of organic material present
- leaves stains
working solutions should be prepared fresh within 24 hours and kept in light protected containers
stock liquids lose Cl concentration over time
corrosive; neutralized by organic material
clo2 gas used in mail center against anthrax
What is organic material?
ex- someone bleeding out in the hospital the blood is a mixture of things; microorganisms saliva and can effect how effective disinfectants are
what is chlorine effective against?
veg bacteria
mycobacteria
viruses
fungal spores
some sporicidal activity
How is chlorine reduced by organic material?
more organic material the less effective
would need to increase concentration to reduce the number of bacteria
How does iodine work?
oxidizes amino acids, fatty acids, nucleotide’s etc; causing denaturation
Iodine
available as an aqueous solution, tincture (solution in alcohol) and iodophor (iodine complexed with carrier molecule to increase solubility and provide sustained release of the halogen eg- povidone iodine
What is iodine effective against?
- enveloped (lipid containing) viruses
veg bacteria, fungi
variable activity against mycobacteria, non enveloped viruses and bacterial spores
list some of the disadvantages of iodine
staining treated items corrosiveness and neutralization by organic material
wescodyne povidone- iodine
alcohols
- ethyl alcohol (ethanol, ETOH)
-isopropyl alchohol (isopropanol, IPA) - flammable
What is the most effective concentration of alcohol and why?
70% in water is most effective concentration
b/c needs h20 to enter membranes and h20 isnt as volatile won’t evaporate quickly
what is alcohol effective against? not effective?
effective against: enveloped viruses veg bacteria longer contact time (10mins) required for any activity against fungi and mycobacteria
variable against non enveloped viruses
no activity against bacterial spores
longer contact times difficult to achieve due to loss by evaporation
phenolics
used in combo with detergents
one of 1st disinfectants to be used by surgeons
vesphene LpH are examples
What are phenolics effective against? not effective against?
effective against
- enveloped viruses
- vegetative bacteria
variable activity against fungo and mycobacteria depending on product
limited activity against non enveloped viruses
no activity against bacterial spores
list some of the disadvantages of phenolics
toxicity
neutralization by hard water
puget unpleasant smell
list some of the advantages of phenolics
not easily neutralized by organic material
non corrosive
Quaternary ammonium compounds
quats have innate detergent action but may be inactivated in the presence of some soaps or soap residues
odorless colorless non irritating and deodorizing
roccal germex zephiran coverage plus microchem
What are QACS effective against? not effective against?
effective vs gram + bacteria
limited activity vs enveloped viruses fungi and gram - bacteria
effectiveness reduced by organic material
glutaraldehyde
- 2-4% aqueous solution often with activator
- use requires adequate ventilation
- activated product has limited shelf life
- controversial product because of adverse health effects including mucous membrane irritation contact dermatitis occupational asthma
- cidex taken off the UK market May 2002
formaldehyde
supplied as solid paraformaldehyde (flakes or tablets) or as liquid formalin (37% in water with 100 ml/l of methanol stabilizer
disinfectant use is typically 4%
less susceptible to inactivation by organic material
corrosive caustic irritant carcinogen
can be neutralized with ammonium bicarbonate
What is formaldehyde effective against? not effective against?
broad spectrum of activity against all classes of microorganisms
hydrogen peroxide
available as a concentrated 37% solution in water (6% in-use solutions)
vapor phase hydrogen perioxide is good volume disinfectant 35-37% solution is converted to vapor phase by heat
leave no residue breaks down to water AND O2
incompatible with aluminum copper zinc brass natural rubber and some plastics
What is hydrogen peroxide effective against? not effective against?
veg bacteria
mycobacteria
fungi
viruses and spores
chlorhexidine
available as 2-4% solution of chlorhexidine gluconate (a biguanide) in a detergent base (used undiluted as as concentrated alcohol based solutions requiring dilution prior to use
alcoholic solutions show superior activity to aqueous solutions
generally sued as a antiseptic (skin disinfectant and hand wash)
What is chlorhexidine effective against?
enveloped viruses and veg bacteria
limited activity against fungi mycobacteria non enveloped viruses
no sporicidal activity
the phenol coefficent
highest dilution of the test solution divided by the highest dilution of phenol that gives no growth of bacteria culture under standard conditions
ex:
at 10 minutes a disinfectant exhibited no bacterial growth at a dilution of 1in 500
phenol exhibited no bacterial growth at 10 minutes at 1 in 95
phenol coefficient of the disinfectant is 500+95=5.26 or 5.36 x greater than phenol
factors influencing efficacy
- surface- topography
- whether we decon a stainless steel safety cabinet vs bricks
- the surface can absorb the disinfectant which effects how it works - temp
- somethings that effective at 2.5 celcius might not be at 4 - relative humidity
- how much vapor pressure is present in the air - water hardness
- more minerals in the water could decrease effectiveness of disinfectant - organic load
- ex cough is a mixture of proteins, virus etc - concentration
- if you use something to dilute it wont effectiveley clean area - contact time
- how long its on surface for
