METHODS OF STERILIZATION

The reusable instruments have already been decontaminated.
We need to select an available method for sterilizing them for reuse in the next procedure.

STERILIZING AND DISINFECTING INSTRUMENTS:
Sterilization is the destruction of all living organisms.
- An item may only be STERILE or NON-STERILE.
- It CANNOT be NEARLY sterile.
- Disinfection, on the other hand is the REDUCTION of a population of pathogenic micro-organisms without achieving sterility.
- In these cases not all bacterial spores are destroyed.

Antiseptics are used in the skin to prevent infection. They are milder than disinfectants e.g. Iodine, Hydrogen peroxide and Chlorhexadine.

There are four methods of disinfecting and sterilizing instruments in Hospital practice:
1. Antiseptic solutions.
2. Boiling.
3. Hot air ovens.
4. Autoclave.

DISINFECTING SOLUTION
- Alcohol (Ethyl + Isopropyl) 70% was the solution most widely used.
- Recently of 0.5% chlorhexidine is widely used for emergency disinfection of surgical instruments
It requires only 2 minutes immersion.
- Where instruments are left for longer periods or stored continuously, addition of one tablet of sodium nitrite 1g will prevent rusting.
As the tablet dissolves over several days, another is added.
- The aldehydes (Formaldehyde & Gluteraldhyde) are powerful disinfectants and sterilizers.
A solution containing 2% glutaraldehyde will disinfect instruments if they are soaked for 10 minutes, and sterilize if left soaking for 10 hours.
The disadvantages are that the solution needs to be fresh, and it can cause staining if left on the skin.
- A detailed list is given at the end of this chapter (Table I.V)

BOILING:
This is still the most widely used method of disinfecting instruments in the World;
- it is simple, quick and reasonably effective, but
- will not destroy certain bacterial spores (tetanus, gas-gangrene)
- and certain viruses.
- Normally, instruments are cleaned, and then boiled for 5 minutes (100 degree C or 212 degree F).
- A boiling water `sterilizer' is badly named, because at a height of 3000 metres water boils at 90 degree C and is thus much less effective.
- This method is obviously not suitable for dressings or drapes.
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