Autoclave quality control:
An autoclave is a device for sterilizing materials and equipment in the laboratory by high pressure steam at a temperature of 121 degrees Celsius for 15 or 20 minutes. This time depends on the type of material and the contents of the autoclave. This device was invented by Charles Chamberland in 1879. Although the autoclave is the best tool for sterilization, we must acknowledge that the prolongation of the heating stage causes a decrease in the quality of nutrients in the complex culture environment. It contains sugar, minerals and metals, and as a result, it damages the cultivation environment.
Therefore, in the sterilization cycle, we should use a shorter time and a higher temperature so that in addition to causing less damage to the culture environment, it is also more lethal for the organism.
The main steps of sterilization:
Sterilization preparation: Loading
including packaging of equipment with chemical indicator.
If we use a tube with a lid, the lid should be loose or covered with aluminum paper.
Autoclave setting: Setting
For example, for liquids and waste and infectious waste and.
Sterilization step: Sterilize
Step of leaving the sterilized items from the autoclave: Unloading
We can open the autoclave door when the pressure is zero and do not stand while opening the door and use heat resistant gloves.
Quality control using chemical strip and biological indicator:
A: Chemical control: Control is performed using TST class 6 chemical strips that control the three factors of time, steam and temperature. Depending on the type of tape purchased, the way to change the color is different.
For example, the yellow color of the tape becomes purple. which indicates the proper operation of the autoclave.
The autoclave must be controlled in every operation using the TST chemical strip and recorded in the form number M-5-75.
B: Sterility-Record label: In addition to measuring sterility, it is possible to record the date of sterilization, the name of the sterilizer and the name of the culture medium on this label.
He used this label in every work series
C: Biological control: Biological control is done using Stearo thermophilus spores, which is done in the following way.
1- Placement step: We place the spore test in the blind spot of the autoclave (usually near the drain pipe). After the complete autoclave cycle, we wait 10 to 15 minutes for the test to cool down.
Safety tip:
After the sterilization process, the liquid inside the test is hot and under pressure, so not observing the necessary cooling time may cause the glass ampoule to burst.
2- Activation: after cooling the test, we break the glass ampoule by pressing the plastic wall.
3- Cultivation: After performing the above steps, the spore is placed at a temperature of 57 degrees Celsius for 48 hours to be checked for culture. We check the tests every 12 to 24 hours. After 48 hours, no color change indicates that the sterilization cycle is sufficient.
How to interpret:
Sterility = lack of growth = blue/purple (primary color)
Non-sterile = growth = yellow color
It takes 48 hours for cultivation. The speed of color change indicates the speed of reproduction
How to remove spores:
All positive tests are discarded after autoclaving for 30 minutes.
Note: Spores that do not have an expiration date should not be used.
Note: Sterilization process control
⋆ It is mandatory in every race
Jabak Tehran
@jabaktehran
This post is written by Sadegh_s6