Introduction:
Sterilization is described as the absence of microbes from an abject. Surgical instruments which come in contact with cut skin, internal organs, bloodstream, and other sterile body parts need to be sterilized. Microbiological substances such as contaminated items also require sterilization before disposal.
What Is Sterilization?
Sterilization is the process of removing or killing all forms of microbes. Different chemicals and physical processes, such as heat, pressure, irradiation, etc., help carry out this process.
Sterilization is used in the medical field for cleaning instruments, gloves, and other types of equipment coming in contact with blood and tissues. There are various ways of achieving sterilization. For example, an autoclave uses high pressure, dry heat, certain chemicals such as glutaraldehyde or formaldehyde, and radiation.
For sterilization to be effective, the appropriate amount of time, contact, temperature, and pressure are needed. Apart from these, the effectiveness of sterilization also depends on the following factors:
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The kind of microorganism present. Certain microbes are difficult to sterilize as compared to others.
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The number of microorganisms present. Killing one or a few microbes is easier than killing many.
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The kind of organic substance that protects or shields microorganisms. For example, the remaining blood or tissue on improperly cleaned instruments works as a protective layer against the microorganisms during sterilization.
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The number of crevices on the instruments lodging the microorganisms. These cracks or rough surfaces become a hub of microorganisms, thus requiring thorough cleaning.
What Are the Different Types of Sterilization?
Physical Sterilization Methods:
Heat sterilization is one of the effective sterilization methods where the microbes are removed by killing their cellular components and enzymes. It is carried out by the following methods:
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Dry Heat Sterilization - This method is carried out on equipment that is sensitive to moisture. Dry heat causes the breakdown of the proteins, thereby killing the microbes.
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Moist Heat Sterilization - Moist heat sterilization is carried out in an autoclave, which produces steam under pressure. This sterilization is also known as steam sterilization. This coagulates the protein present in the microbes, thus killing them eventually.
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Filtration - In this sterilization process, filters with small pores are used to filter the liquid from the bigger particles and microbes.
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Irradiation - Irradiation uses radiation to get rid of microbes.
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Sound Waves Sterilization - Sound waves ranging from 20 to 40 kilohertz are passed across the fluid for sterilization.
Chemical Sterilization Methods:
Chemical sterilization is used to sterilize plastic instruments and biological specimens. It is of two types:
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Gas Sterilization - In this method of sterilization, gas is used in a closed, pressurized chamber that is heated. The chemical used in gas sterilization is ethylene oxide, formaldehyde, nitrogen dioxide, and ozone.
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Liquid Sterilization - In liquid sterilization, the object is immersed in a liquid that kills the microbes. However, liquid sterilization is less effective than gas sterilization. Commonly used liquid sterilization agents are glutaraldehyde, hydrogen peroxide, and hypochlorite.
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Cold Sterilization - This sterilization is carried out at lower temperatures. Cold sterilization uses chemicals, radiation, and filters. It is carried out for heat-sensitive objects requiring sterilization.
What Is the Principle of Heat Sterilization?
High-pressure steam is used to sterilize instruments in an autoclave or oven. High-pressure hot air sterilization is quite effective but difficult to perform. Therefore, it is mostly used to sterilize equipment and instruments in hospitals. Dry-heat sterilizers can be used in humid climates but require an uninterrupted supply of energy. Dry heat sterilization requiring higher temperatures can be used on metal and glass equipment. Dry heat sterilization is an effective means to sterilize surgical instruments. It is used in a convection oven. The oven has an insulated stainless steel chamber and perforated shelves that allow the circulation of hot air. Dry heat sterilization is carried out by thermal conduction. In this, the heat is first absorbed by the outer surface of the organism, which then passes inside it. The microorganisms die due to protein destruction. Dry heat sterilization has a longer duration as compared to steam sterilization. In steam sterilization, the moisture increases the penetration of heat within the microorganism, thus killing them in no time.
What Is the Principle of Steam Sterilization?
Steam is very effective in sterilizing surgical equipment. Saturated steam carries thermal energy, which is quite effective than hot, dry air. Steam under pressure carries thermal energy swiftly as compared to dry, hot air. The outer protective layer in a microorganism can be easily softened with steam leading to coagulation of the proteins in them, thus killing the microorganisms. Containers with oily materials may act as a protective environment for the microbes, thus hampering sterilization.
What Is the Principle of Chemical Sterilization?
Chemical sterilization is an alternate method of sterilization when heat sterilization cannot be performed. If the object is such that high heat would damage them or is not available, then chemical sterilization comes into play. Glutaraldehyde and formaldehyde are common chemical disinfectants. In chemical sterilization, the object is soaked for ten hours in two to four percent of glutaraldehyde solution or one day in eight percent of formaldehyde. The objects sterilized with glutaraldehyde and formaldehyde can get stained, so it is better to wash them with sterile water. Glutaraldehyde and formaldehyde are expensive chemical disinfectants. Formaldehyde has been found to have a carcinogenic property and irritates the skin, eyes, and respiratory tract. While using these sterilizing agents, it is better to wear protective eyeglasses and gloves to avoid contact with the skin, reduce the time of contact, and use them in well-ventilated areas. The sterilized equipment should be kept wrapped in sterilized containers.
What Is the Principle of Gas Sterilization?
In gas sterilization, formaldehyde gas is used for sterilization purposes. Formaldehyde gas has been used to fumigate rooms. Ethylene oxide is used to sterilize instruments that cannot be sterilized with heat and moisture. Ethylene oxide sterilization needs different equipment for its use, thus, making it a difficult choice for sterilization.
Conclusion:
Sterilization is the process by which the object is made free from microbes. There are several types of sterilization techniques, like dry heat, steam, gas, liquid, radiation, etc. Failure to sterilize can lead to serious consequences like severe infections and even death. Thus proper sterilization along with appropriate monitoring should be done.
