Question

Sterilization Techniques Write about the procedure/test in general. What is the purpose? How many sterilization techniques did you observe? How does it help the Medical Microbiologists inside the labs?

Answer 1

• Sterilization: It is the process in which life or other biological agents are killed, removed, eliminated or deactivated.

• There are mainly five techniques of Sterilization which are as follows:

1. Wet Heat (Autoclaving)
2. Dry Heat (flaming or baking)
3. Filtration (by using filters, e.g. membrane filters and scintered glass funnels)
4. Use of Solvents (e.g. ethanol and isopropanol)
5. Radiation (e.g. electromagnetic radiations which are UV, X-rays and gamma rays)

• Sterilization details in brief:

1. Wet Heat/Moist heat Sterilization: It involves use of hot air with full of water vapor which causes destruction of micro-organisms by denaturation of proteins.

This technique can be use by two ways:

1. Tyndalization: It uses three successive steam treatments over the course of three days
2. High pressure/autoclave/pressure cooker: In this samples are placed in steam chamber and then it is closed and heated so that steam forces air out of the vents. Then pressure is applied till the temperature reaches 121 degree Celsius which is maintained for 15-30 minutes. Mainly use for sterilization of heat resistant tools and materials in microbiology labs.

2. Dry Heat/flaming:

Dry heat sterilization uses high temperatures for longer period of time which has no or minimal moisture involved.

Example is Hot air oven which has heating coils at the bottom and provides hot air.

Flaming involves exposing of objects to direct flame/fire.

Dry heat sterilization is use for glassware, oils, powders and metal instruments.

3. Filtration:

Filtration includes separation of organisms based upon size. In sterilization mostly membrane filtration is used.

Membrane filtration traps contaminants larger than the pore size on the surface of the membrane.

Used for liquid and gases sterilization.

4. Use of solvents for sterilization:

In this, different solvents (ethanol or isopropanol) are used by diluting them with water which causes rupturing by osmosis.

This technique is used for quick sterilization of lab equipment and surfaces.

5. Radiation:

There are two types of radiation used for sterilization, ionizing radiation and non-ionizing radiation.

Ionizing radiation is the use of short wavelength, high-intensity radiation to destroy microorganisms. Example is gamma or X-rays that react with DNA resulting in a damaged cell. Used for sterilization of equipment.

Non-ionizing radiation uses longer wavelength and lower energy. This can only be used for sterilizing surfaces. Example is ultraviolet light.

• Purpose of sterilization:

As mentioned above sterilization reduced microorganisms and potential pathogens. Thus, avoids transmission of all living microorganisms.

• Use of Sterilization in lab:

1. Medical microbiology involves study of microorganisms and their role in causing the disease.
2. During working medical microbiologist uses various medical tools/devices which requires sterilization to avoid buildup of microorganisms and various other diseases. It will also help in avoiding spread of diseases.