moist heat sterilization
TRANSCRIPT
MOIST HEAT STERILIZATION
Principle-Denaturation & coagulation of proteins due to the latent heat present in
steam
Advantages of steam –Latent heat liberated on condensing on a cooler
surface increases the temprature of that surface
What is Moist heat Sterilization?
Types of Moist heat Sterilization
•Pasteurization•Inspissation or Fractional Sterilization
Hot water below boiling point
•Tyndallization or Intermittent Sterilization
Boiling water /steam at atm pr
•AUTOCLAVE Saturated steam
Pasteurization
•63 C for 30 minutes
Holder Method
•72 C for 15-20 seconds
Flash Process
Heat labile fluids may be disinfected
It is the process of thickening
by dehydration
Inspissation
Media such as Lowenstein –Jensen media and Loeffler’s serum are rendered sterile by heating at 80-85 C for half an hour on three consecutive days
Tyndallisation
Principle: The first exposure kills all vegetative bacteria and the spores since they are in a favourable medium will germinate and be killed on subsequent occasions
Though generally adequate this method may fail with spores of certain anaerobes and thermophiles
The Autoclave was invented by Charles Chamberland in 1879
AUTOCLAVE
Definition
Autoclave is a pressurized device designed to heat aqueous solutions above their boiling point at normal atmospheric pressure to achieve sterilization
Reliable sterilization with moist heat requires temperatures above that of boiling water.
These high temperatures are most commonly achieved by steam under pressure in an autoclave. .
Need for autoclaving:
Autoclaving is the preferred method of sterilization unless the material to be sterilized can be damaged by heat
or moisture
Liquid H2O cannot be heated above 100°C in an open vessel
At 100°C boils
H2
O heated in a sealed vessel
Pressure rises
Boiling point of H2
O is raised
Air removal
Downward displacement
Steam pulsing
Vacuum pumps
Superatmospheric
Subatmospheric
Process
Biological indicators are the only process indicators that directly monitor the lethality of a given sterilization process. Spores used to monitor a sterilization process have demonstrated resistance to the sterilizing agent and are more resistant than the bioburden found on medical devices.
Bacillus stearothermophilus Thermophilus aquaticus
Spore Test
If the autoclave does not reach the right temperature
the spores will germinate when incubated and their
metabolism will change the color of a pH –sensitive
chemical.
Any Questions???