The principle on which instrument shown in the photograph below cause sterilization is?
A. Steam under pressure.
B. Dry heat
C. Convection current in water molecules.
Ans:B. Dry heat.
The instrument shown in the picture above represents hot air oven.
Hot air ovens .
- It is the process of killing all microorganisms (bacterial, viral, and fungal) with the use of either physical or chemical agents.
1. Sterilization by heat:
Sterilization by Moist Heat
- Moist heat acts by denaturation and coagulation of protein, breakage of DNA strands, and loss of functional integrity of cell membrane.
- Sterilization at 100°C:Boiling/Steaming.
- Single exposure/Tydallization(Fractional Sterilization).
- Sterilization above 100°C: Autoclaving.
Sterilization by Dry Heat
- Mechanisms. (1) Protein denaturation, (2) Oxidative damage, (3) Toxic effect of elevated electrolyte (in absence of water).
- Dry heat at 160°C (holding temperature for one hour is required to kill the most resistant spores). The articles remain dry.
- Red heat,/Flaming/Sterilization by Hot Air
- Hot Air Oven (Sterilizer). It Is one of the most common method used for sterilization.
- Glass wares, swab sticks, all-glass syringes, powder and oily substances are sterilized in hot air oven. For sterilization, a temperature of 160°C is maintained (holding) for one hour. Spores are killed at this temperature. It leads to sterilization.
2. Chemical Sterilization:Ethylene Oxide,Nitrogen
- Dioxide,Ozone,Glutaraldehyde,Formaldehyde,Hydrogen peroxide,Peracetic acid.
3. Radiation Sterilization:Ionizing and non-ionising Radiation