13. Disinfection & Sterilisation Flashcards
What agent should be used for high level disinfection with heat sensitive surgical instruments?
Aldehyde
Why is N95 mask called N95?
It prevents 96% of particles of very small (0.3 micron) particles
List out all the disinfection chemicals we use.
- Glutaraldehyde (heat sensitive items)
- Hypochlorites/Chlorine compounds (mainly kills virus)
- Iodine-based/Lodophors (wide range: bacteria, virus, fungi, only sporicidal antiseptic)
- Phenolics (domestic disinfection, but poor virucidal & sporicidal)
- 70% Alcohol (skin disinfection)
- Chlorhexidine (for plaque control)
NOTE: PROF SAY DUNNIT MEMORISE THE CHARACTERISTICS OF ALL THE DISINFECTING AGENTS!! SO IGNORE THE NEXT FEW CARDS
What is Gluraldehyde used for + pros and cons?
Pros:
1. For heat-sensitive items + non-damaging to metals, plastic, rubber
2. Clean semi-critical objects & endoscope
3. Sporicidal but slow activity against mycobacteria (TB), but still works ig
Cons:
1. Irritant to skin, eyes, respiratory tract
What is Hypochlorites/Chlorine compounds used for + pros and cons?
Pros:
1. Mainly kills virus, some bacteria and spores
2. For environmental cleaning: blood spills on floor & instruments
- extra strong (1%, 10000ppm): blood spillage
- strong (2.5%, 2500ppm): lap pipette jars, antiseptic for dirty wounds
- strong (1%, 1000PPM): general environmental use
Cons:
1. Caustic(burn/corrode) to tissues & corrodes metals
(Bleach)
What is Iodine-based/Lodophors used for + pros and cons?
Pros:
1. Kills wide range of bacteria, virus, fungi (fast anti-viral action on clean surface)
2. For surface disinfection & antiseptic
3. Iodine: only antiseptic that is sporicidal
4. Cheap & effective
Cons:
1. Corrodes metals, cause allergy, inactivated by organic matter
What is Phenolics used for + pros and cons?
Pros:
1. For domestic disinfection: washing, cleaning floors
Cons:
2. Poor virucidal & sporicidal, taint food, corrosive
What is 70% Alcohol used for + pros and cons?
Pros:
1. For skin disinfection (antiseptic) => hand rub
2. For surface disinfection, rapid action
Cons:
1. Does not kill spores (does not penetrate organic matter)
2. Evaporates quickly => no residual effect
What is Chlorhexidine used for + pros and cons?
Pros:
1. Plaque control: adsorbs to enamel & salivary pellicle => retain antimicrobial activity
2. Antiseptic: sustained/retentive action on skin => hand sterilisation for surgery
Cons:
1. Limited against virus, does not kill spores & mycobacteria
2. Unpleasant taste, may discolour tooth/gingiva
What happens in the instrument processing area?/Steps for infection control?
- Cleaning & decontamination
- Disinfection: decreases no. of viable microorganisms, except spores & prions
- Sterilisation: completely remove all viable microorganisms, including spores (+ preparation & packaging b4 sterilisation)
- Assessing sterilisation + storage!!
What are the categories of infection control?
- Critical: penetration of tissue by intent/accident => sterilisation (e.g. scalers & blades)
- Semi-critical: contact intact mucous membrane => high lvl disinfection (e.g. mouth mirror, impression tray, handpiece)
- Non-critical: contact intact skin => low-level disinfection/cleaning (e.g. facebow)
IMPT!!!
List the microorganisms in decreasing hardiness.
Spores>TB>normal bacteria>virus
Methods of sterilisation are..
- Heat sterilisation (moist
- Ionising radiation
- Chemical
- Gas plasma
- Glutaraldehyde
Definition of Disinfection:
A process used to reduce the number of viable micro-organisms on a surface or in a load, but which may not necessarily inactivate some microbial agents (e.g. spores & prions)
Spores are a prob in SG, prions not so much
Definition of Sterilisation:
A process which renders a product free from viable micro-organisms. It achieves the complete killing or removal of all types of micro-organisms, including spores. (of tetanus and gas-gangrene bacilli which are resistant to most disinfectants, and spores which are more resistant to heat than non-sporing organisms.)
Temp and pressure of autoclave (MUST MEMORISE SAID PROF)
121*C, 1 atmosphere or 15 pounds pressure (p.s.i), in 15 minutes
How do you monitor and know that your steam autoclave works? (MUST MEMORISE)
Bacillus stearothermophilus spore strips
Storage shd be..
Aseptic!
List the control tests used to assess sterilisation. (MUST MEMORISE HEHE)
- Chemical
- Browne tubes : measures temp-time, heat sensitive dye
- Bowie-dick tape test : ensure air properly removed => ensure steam penetration (zebra line tape) - Physical: leak test, rototherm charts, thermocouple (just make sure the temp hits by looking at dials etc)
- Microbiological: spore strips (Bacillus subtilis, Bacillus stearothermophilus)
What spores are used for the microbiological spore test? (MUST MEMO!!)
Bacillus Subtilis & Bacillus Stearothermophilus
Flash sterilization should not be used for.. (memorise)
Implantable devices
- cuz those will stay in the patient, dangerous if theres any contaminants
