Sterilization By Autoclaving
By Dewi Susanti
Autoclaving is one of the commonly used methods of sterilization in the medical world. An autoclave is the machine that does this form of sterilization. The procedure kills all forms of microorganisms by utilization of steam and high pressure. For the procedure to be effective the materials to be autoclaved should be completely saturated with steam.
How autoclaving works
It employs the use of pressurized gas. For this matter steam. When water is heated to form steam and steam is exposed to high pressure, then the temperature of steam increases. It is able to attain a temperature of 121oC. This occurs in a closed system. The temperature achieved is adequate for complete sterilization of all medical equipment and wastes. No pathogen is able to survive this high temperatures. Even bacterial spores are destroyed in the process.
Preparing substances for the process
Liquids that require sterilization are put in large containers that are not closed or loosely capped. This is to allow steam to penetrate entirely in the liquids for the process to be effective. Other materials are placed in autoclaving bags. If the autoclave is overloaded it will take more time for complete steam saturation of the contents, which means that it will take long for the items to be sterilized effectively.
How to test if sterilization has occurred
Two most commonly used methods is the use of indicator tapes and the use of bacterial endospores in a vial. This test materials must be put at the center of the item(s) been sterilized. After the procedure is over the tape will change color to indicate that effective sterilization has taken place. On the other side the endospores in the vial are inoculated onto a sterile media and they are observed for growth. If any growth occurs in a sterile media, then it is an indication that sterilization was not achieved in the process.
Items that are commonly autoclaved.
Used bacterial media that contains pathogens have to be sterilized before they are disposed in the sewers. The is an important step in the control of infectious diseases. Media that is used for culture is also sterilized to render it free of any microorganisms. Medical equipment like those used in the theater can also be sterilized by this method. Same applies to glassware that is used in the microbiology lab. Any item that is sterilized using an autoclave has to be able to withstand the high temperatures.
Safety for autoclave technicians
Because the autoclave uses steam under high pressure it can pose a potential risk to the user if not properly used. It is important to ensure that laboratory technicians are well trained on how to use the machine to avoid laboratory accidents. The technician should be clothed in protective clothing like heat proof gloves and lab coats.
Finally for effective autoclaving ensure that the right procedures are followed. Do not be in a hurry to open the autoclave after the sterilization process wait for around 10-15 minutes for it to cool, then open the lid slowly as you allow steam to escape.