Different Methods Of Sterilization And Disinfection Of Hospital Products

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In this article, we will share detailed information on different methods of sterilization and disinfection of hospital products. And if you are interested in more articles, comment with us below.

Disinfection:

Disinfection is a process of destroying all pathogenic or harmful organisms that cause disease or infection.

Sterilization:

Sterilization is commonly defined as an event that involves the killing of all microorganisms including fungi, bacterial spores, bacteria, germs, viruses ( HIV and Hepatitis).

Antiseptics:

Antiseptics are disinfectants that can be applied to the skin, to minimize the number of pathogens.

Germicide (Bactericidal Agents):

Bactericidal agents are used for destroying bacteria and their growth by preventing their multiplication process.

Decontamination:

The event that provides an area free from harmful substances like microorganism, a radioactive substance, harmful chemicals, etc.

 

Methods Of  Sterilization And Disinfection Of Hospital Products:

Sterilization and disinfection involve various parameters and procedures, these procedures are categorized into different types based on the agents applied.

The different agents used are as follows:

Physical Agents:

1. Heat:

The mechanism of killing through heat is because of oxidative damage, denaturation of protein, and the effect of toxicity of elevated electrolyte levels.

The main principle of heat sterilization is that sterilization duration is inversely proportional to temperature.

* Dry Heat:

• Flaming: In this method, the sterilizing material is held in a bunsen burner flame until they become red hot. Infective materials should be disinfected before flaming. Materials sterilized using the flaming method are the tips of forceps, searing spatulas, and inoculation loops.

• Incineration: In this method, the materials are completely destroyed. Animal carcasses, bodies, contaminated cloth, plastics (polythene and PVC), and pathological materials are destroyed using incineration.

• Hot-Air Oven: Most commonly used method is the hot-air oven. The materials to be sterilized are heated at the temperature of 160 for one hour(170 degrees for 18 minutes, 180 degrees for 7.5 minutes, and 190 degrees for 1.5 minutes). The materials sterilized using a hot-air oven are scalpels, some drug products, glasswares, all-glass syringes, forceps, swabs, etc.

* Moist Heat:

• Pasteurization: In this method, all non-sporing pathogens of the milk are destroyed at a temperature of 63 degrees for 30 minutes ( 72 degrees for 15-20 seconds) then followed by cooling at 13 degrees or below. The non-sporing pathogens killed by using pasteurization are salmonellae, mycobacteria, and brucellae.

• Inspissation: In this method, some of the cultural media such as Loeffler's serum and L-J media are made sterile by rising temperature to 80-85 degrees for 30 minutes on three sequential days in the container called inspissator. The pathogens killed by this process are spores of Clostridium botulinum, non-sporing bacterias like Enterococcus and Staphylococcus aureus, and some viruses ( poliovirus and hepatitis B  virus).

• Boiling: In this method, boiling of materials at 90-100 degrees destroys vegetative bacterias, but sporing bacterias are destroyed at prolonged intervals of boiling.

• Intermittent Sterilization Or Tyndallisation: Tyndallisation works on the principle that a single exposure of pathogens kills all the vegetative forms of the bacteria leaving spores, spores which generate into vegetative forms are killed in successive heatings. Temperature is 100 for 20 minutes.

• Autoclave: Autoclave works on the principle that water will boil when its vapor pressure is equal to the surrounding atmospheric pressure. The temperature at which the materials are sterilized is 121 degrees for 15 minutes ( 126 degrees for 10 minutes and 134 degrees for 3 minutes. The materials sterilized in the autoclave are laboratory wares, gowns, pharmaceuticals products cultural media, instruments, dressings, etc.

2. Radiation:

• Nonionizing Radiation: In this method, electromagnetic waves with wavelengths higher than visible light are used. To sterilize the prepacked objects like catheters and syringes uses infrared rays and to sterilize operation theatres, laboratories, etc.

• Ionizing Radiation/ Cold Sterilization: In this method, there is no increase in temperature, hence called cold sterilization. Radiations used are cosmic rays, gamma rays, and X-rays. Commonly gamma rays are used to sterilize swabs, catheters, cardboard, syringes, fabric, oils, greases, etc.

3. Filtration:

• Sintered Glass Filters: These filters are prepared when finely powdered glass particles are fused by heating. These are easy to clean but are expensive and sharp to handle. 

• Asbestos Filters: These filters are single-use disposal materials. The main drawback of this filter is due to its carcinogenic potential, it is the least used. Sterimat and Seitz filters are examples of Asbestos filters.

• Membrane Filters: These filters are commonly prepared using some polymers or cellulose esters. The main application of this filter is to sterilize water, analysis, sterility testing, etc. 

• Candle Filters: These filters use the property of variations in porosity. These filters are used to filter drinking water and filter water for industrial uses, etc. The filters are categorized into two types: Diatomaceous earth filters (Mandler and Berkefeld filters), Unglazed ceramic filters (Doulton and Chambered filter).

4. Ultrasonic and sonic vibrations:

The high-intensity sound waves are used to treat wastewater and kill some bacterial spores. These waves are used to find the distance of pathogens and destroy them.

Chemical Agents:

1. Alcohols: The main mechanism of alcohols is denaturing of bacterial protein making them less harmful when used as an aqueous solution within the range of 60-90 percent in the solvent. Alcohols are highly flammable substances and hence should be stored in cool places and far from infants. When you use alcohol-based stellium on your hands, wait until it gets evapourate and this ensures the killing of pathogens on your hands. The most commonly used alcohols for sterilization are isopropyl and ethyl alcohols. They are used to disinfect hospital pages, stethoscopes, oral and rectal thermometers, scissors, etc.

• Ethyl

• Trichlorobutanol

• Isopropyl

2. Dyes: These are used for wounds and skin antiseptics. They are of two types:

• Acridine Dyes are highly active against gram-positive organisms like Mycobacterium tuberculosis.

• Aniline Dyes are highly active against gram-negative organisms.

3. Gases: These agents are effective against all variety of pathogens including spores and viruses. Few types of gases that are used as a disinfectant are as follows:

• Formaldehyde

• Betapropiolactone

• Ethylene Oxide

4. Aldehydes: These are the alkylating agents that are highly reactive against most of the microorganisms. Glutaraldehyde and formaldehyde are the most commonly used aldehydes for sterilizing purposes.

• Glutaraldehyde: They are used to disinfect medical instruments like dialyzers, respiratory therapy equipment, endoscopes, anesthesia, spirometry tubings, transducers, etc.

• Formaldehyde: They are used for the sterilization of instruments, laboratories, fumigating wards, sick rooms, catheters, etc.

5. Phenolics: These are highly reactive against viruses, tuberculosis, fungus, bacterias, etc.

Hexachlorophene and triclosan are the most commonly used biocides in the phenolics group. Chlorhexidine is a nontoxic skin antiseptic, less effective against gram-negative organisms, and is highly effective against gram-positive organisms.

6. Peroxygens:

• Hydrogen Peroxide: This is the most widely used biocides for antisepsis, sterilization, and disinfection. These are effective against bacterial spores, viruses, yeasts, bacteria, high effective to gram-positive bacteria. They act on DNA, lipids, proteins, and other cell components.

7. Metallic Salts: These salts depending upon their concentration show greater action on pathogens. They act as protein coagulants.

• Mercury Salts are highly toxic to use. 

• Silver Salts have limited use in the aqueous solution.

• Copper Salts act as fungicides.

8. Halogens:

• Chlorine: Hypochlorites are the most commonly applied chlorine disinfectants in solid or liquid form. They show greater action against bacteria, fungi, spores, viruses, and mycobacteria.

• Iodine: Tinctures or iodine solutions are commonly used as antiseptics on tissue or skin. 

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