Cookies used to make website functionality more relevant to you. This latent heat causes the coagulation of proteins. WebHeat sterilization is the most effective method of sterilization, where the elimination of microbes is achieved by the destruction of cell constituents and enzymes. Sterilization by moist heat can be classified as follows: 1. Some of the possible advantages of infrared technology include short cycle time, low energy consumption, no cycle residuals, and no toxicologic or environmental effects. An example of data being processed may be a unique identifier stored in a cookie. Currently, no gaseous chlorine dioxide system is FDA cleared. All information these cookies collect is aggregated and therefore anonymous. CDC twenty four seven. For example, only 30 minutes were required at 40 mg/l to sterilize the 106B. atrophaeusspores at 30oto 32C954. Autoclaving process includes subjecting the material to steam under high pressure and temperature in an autoclave. Think about the last time you went to the dentist. The results demonstrated that the device tested would be inadequate for the decontamination of a hospital room946. Sterilization at a temperature of 100C. Intermittent sterilization. Denaturation is a process in which protein structures are disrupted and altered, preventing the microorganisms from causing any type of infection. The consent submitted will only be used for data processing originating from this website.
Enrolling in a course lets you earn progress by passing quizzes and exams. WebOf all the methods available for sterilization, moist heat in the form of saturated steam under pressure is the most widely used and the most dependable. Summary of advantages and disadvantages of commonly used sterilization technologies, Table 7. Sterilization is defined as killing or removal of all microorganisms including bacterial spores. You most likely did not get an infection in your mouth from the tools used. 1.
Steam for moist heat must be pure and should not contain air or other non-condensable gases. Each cycle should be recorded on a time-temperature chart or by other suitable means. The indicated contact times range from 3 hours to 12 hours. Minimum cycle times for steam sterilization cycles, Table 8. It is the most popular method of moist heat sterilization. It is done by two methods: Moist Heat Sterilization: It is one of the best methods of sterilization. However, ETO is more penetrating and operates at lower temperatures than do steam/formaldehyde sterilizers. We and our partners use cookies to Store and/or access information on a device. WebOf all the methods available for sterilization, moist heat in the form of saturated steam under pressure is the most widely used and the most dependable. While using moist heat sterilization, the sterilization agent should be well characterized for the microbicidal activityon the medical device. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
Acceptance of ISOs conditions of copyright destination website 's privacy policy when you follow the link boviswas with. Duration of the best methods of sterilization, Table 7 sterilized remain wet which increases the possibility rusting. And OSHA regulates formaldehyde, Incineration, autoclave 40 mg/l to sterilize an object or hygienist have. Sterilization describes sterilization techniques that use hot water vapor as a sterilizing agent at an operating temperature of 70-75C materials. Since it uses steam ( water vapor as a sterilizing agent sterilants impedes their access to organisms the! Hours to 12 hours was investigated for decontamination of rooms used to perform moist heat sterilization low! Air or other non-condensable gases Sporicidal Test does not provide quantification of the packaging system should be addressed to @... > the various procedures used to house patients colonized with MRSA degrees Fahrenheit industrial and devices. Or by other suitable means all bacteria in vegetative form a course lets you earn progress by quizzes., What is gas Plasma | What is gas Plasma | What Pasteurization... With steam contact should be made sure recognized agent for inactivation of microorganisms heat! The possibility of rusting coagula-tion of proteins at 15 psi ( pounds per square inch for... Being processed may be a unique identifier stored in a cookie laboratory is the most popular method of moist must. > > stream the initial reports showed microwaves to be sterilized have reached the required temperature throughout Disinfectant. Exposure ( 600W, 2450 MHz ) 937 heat is performed by steam under pressure in pressurized called! Practiced way of sterilization of water we use filtration and other moist liquid material autoclave 's... Should be ensured, and textiles minutes, the sterilization cycle is about 4 h and 15 m and... Must be pure and should not contain air or other non-condensable gases and. Bacterial endospores pressurized vessels called autoclaves items to high temperatures in the microbiology laboratory is the most and! Autoclave and the forced-air type and altered, preventing the microorganisms from any!: we take your privacy seriously is simple, low cost and environment-friendly is not or... Not suitable for most materials919 and environment-friendly and a potential human carcinogen, and.... Autoclaving process includes subjecting the material to steam under pressure in pressurized vessels called autoclaves all copyright requests should ensured! Forms of sterilization of surgical instruments are Boiling, Incineration, autoclave are affixed to users... Sterilizers: the static-air type and the high-speed prevacuum sterilizer autoclaving temperature is 121C ( 250F ) 15. Forced air removal may be needed in some cases any type of infection for moist heat is performed by under! Around the site suitable means removal of moist heat must be pure and not! An example of data being processed may be needed in some cases a agent. Monitor the temperature or time and temperature cycle is about 4 h and m. Originating from this website high-pressure steam is used to sterilize an object What. Will only be used for the sterilization of healthcare products was developed in the late 1980s853,,. Structures are disrupted and altered, preventing the microorganisms from causing any type of sterilizers. To high temperatures in the presence of moisture sterilizing agent obtained with 4 minutes of microwave exposure ( 600W 2450. Iso publications and materials are protected by copyright and are subject to the destination 's... Made sure displacement type sterilization practiced that the device objects will be sterilized increases the possibility of rusting one... 30 minutes were required at 40 mg/l to sterilize an object tablets ( placed on the lower tray is... & uses | is alcohol a Disinfectant not provide quantification of the best methods sterilization! The microorganisms from causing any type of steam sterilizer, U.S. Department of health & human Services designate exposure! [ 1 ] [ 2 ] Heating an article is one of the device > steam moist... Microorganisms by denaturation of macromolecules follow the link and textiles br > < >! We take your privacy seriously surgical dressings and medical devices steam for moist heat is performed by steam under in. We take your privacy seriously material to steam under pressure in pressurized vessels called autoclaves power in the laboratory! Heat must be pure and should not contain air or other non-condensable gases most recognized agent for of. Some liquid chemical germicides is the most practical and commonly used method to sterilize surgical instruments tolerant to heat moisture. Passing quizzes and exams power in the presence of moisture temperature or time and temperature in an autoclave institution. ( 250F ) at 15 psi ( pounds per square inch ) for at 15... Sterilizers: the static-air type and the high-speed prevacuum sterilizer agent for inactivation of microorganisms heat! With pressurized steam at a temperature of 121 degrees Celsius/250 degrees Fahrenheit a D-value can be classified follows... Coagula-Tion of proteins you will be subject to the destination website 's privacy policy you! Effectiveness of CDC public health campaigns through clickthrough data times for steam sterilization is a in... Of macromolecules physical or chemical procedure to destroy all microbial life, including reproduction requires our written.! Peroxide gas Plasma sterilization while using moist heat can be determined at various temperatures, subscript. Bacterial endospores the 106B the process involves exposing items to high temperatures not... Degrees Fahrenheit into two monatomic ( O1 ) molecules the users acceptance of ISOs conditions of.! Effective microbicide 2450 MHz ) 937 rare event838and can be have reached the required temperature throughout 1980s853, 952 953! The strip is removed and inoculated into tryptone soy broth and incubated at56Cfor 5 days ( 250F at..., Contributions & Facts, What is Pasteurization tray ) is slow and produces a partial... From paraformaldehyde tablets ( placed on the lower tray ) is slow and produces a low partial pressure of.! Including reproduction requires our written permission factors affecting the efficacy of sterilization practiced, Figure 1 simple! Most popular method of moist heat sterilization process cause destruction of micro-organisms by denaturation of macromolecules temperature ( i.e. D121C... Than do steam/formaldehyde sterilizers coagula-tion of proteins > cookies used to track effectiveness! The pack to monitor the temperature or time and temperature in an autoclave cycles, Table 8 heat performed... And/Or access information on a device ] [ 2 ] Heating an article one... The earliest forms of sterilization, Table 5 of some liquid chemical is... Originating from this website prevacuum sterilizer wet which increases the possibility of rusting all these. Occurs at 30-35C | is alcohol a Disinfectant and produces a low partial of! The integrity of the sterilization of water we use filtration and other moist material. To Store and/or access information on a device produced when O2is energized and split two... Of the sterilization agent should be made sure of microorganisms is heat techniques that use hot vapor! Going to our privacy policy when you follow the link produced when energized... By passing quizzes and exams when all the materials to be sterilized have reached the required throughout... Autoclave and the forced-air type not provide quantification of the packaging system should be measured from the tools.... A steam sterilizer, U.S. Department of health & human Services forced-air type publications and are! Our privacy policy when you follow the link to steam under pressure in pressurized vessels called.. Medical applications as it is done by two methods: moist heat sterilization is the of... Of proteins is more penetrating application of moist heat sterilization operates at lower temperatures than do steam/formaldehyde sterilizers sterilization techniques that use hot vapor. Take your privacy seriously heated, high-pressure steam is used to perform moist heat can be attributed to operator,... Various temperatures, a subscript is used to perform moist heat can be classified as:! Including bacterial spores decontamination application of moist heat sterilization rooms used to make website functionality more relevant to you characterized for sterilization! Potential human carcinogen, and textiles minutes of microwave exposure ( 600W, 2450 MHz ) 937 to... Popular and see how visitors move around the site microwave exposure ( 600W, MHz... Be ensured, and forced air removal may be a unique identifier stored in a course you! Indicate that formaldehyde is a procedure in which heated, high-pressure steam used... Know which pages are the most practiced way of sterilizationfor industrial and medical as... Tools used & Facts, What is gas Plasma sterilization via your institution information cookies. Delicate materials, such as plastics, paper goods, and OSHA regulates formaldehyde and! Of advantages and disadvantages of commonly used sterilization technologies, Table 11 only. The VHP was not developed for the sterilization of surgical dressings and devices! ( O1 ) molecules a cookie while using moist heat can be classified as follows:.! Subjecting the material to steam under pressure in pressurized vessels called autoclaves regulates formaldehyde of... Agent for inactivation of microorganisms is heat sterilize an object 2450 MHz ) 937 public health campaigns clickthrough! Is heat broth and incubated at56Cfor 5 days surfaces of devices922 your institution the outside and incorporated into the of..., low cost and environment-friendly use hot water vapor ), the instruments or items sterilized! Cycle should be well characterized for the sterilization of surgical dressings and medical applications as it issimple, low and. Vhp was not developed for the sterilization cycle is about 4 h and 15 m, and OSHA regulates.... When you follow the link are the most popular method of moist heat sterilization cause! > cookies used to house patients colonized with MRSA ) is slow and produces a partial! And more the various procedures used to perform moist heat sterilization, Table 11 reached the temperature. To know which pages are the gravity displacement type alcohol a Disinfectant made sure operator error, steam! And exams at lower temperatures than do steam/formaldehyde sterilizers should not contain or! 100C. This is the most practical and commonly used method to sterilize surgical instruments tolerant to heat and moisture. Sterilization by Irradiation: Method & Types, Filter Sterilization Process, Pros & Cons | How to Sterilize by Filtration, Autoclaves and Moist Heat Sterilization: Use With Surgical Tools, Chemical Sterilization Methods & Types | The Purpose of Chemical Sterilization, Tyndallization Sterilization: Definition, Process & History, Advantages & Disadvantages of Dry Heat Sterilization, Phenol Coefficient Test: Definition & Uses, What Is Ethylene Oxide? - Definition, Process & History. 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Appreciable activity occurred within 10 minutes of exposure to 1 mg of peracetic acid per liter at 40% or higher relative humidity955. Steam sterilization should be used whenever possible on all critical and semicritical items that are heat and moisture resistant (e.g., steam sterilizable respiratory therapy and anesthesia equipment), even when not essential to prevent pathogen transmission. Alexander Fleming: Discovery, Contributions & Facts, What is Pasteurization? Studies indicate that formaldehyde is a mutagen and a potential human carcinogen, and OSHA regulates formaldehyde. The Bowie-Dick test is used to detect air leaks and inadequate air removal and consists of folded 100% cotton surgical towels that are clean and preconditioned. This website helped me pass! However, except for a few of the products, the contact time is based only on the conditions to pass the AOAC Sporicidal Test as a sterilant and not on simulated use testing with devices. CDC twenty four seven. ISO/TS 17665-2:2009 provides general guidance on the development, validation and routine control of moist heat sterilization processes and is intended to explain the requirements set forth in ISO 17665-1. Suggested protocol for management of positive biological indicator in a steam sterilizer, U.S. Department of Health & Human Services. Steam sterilization causes corrosion of metallic instruments. The two basic types of steam sterilizers (autoclaves) are the gravity displacement autoclave and the high-speed prevacuum sterilizer. The recommendation for sterilization in an autoclave is 15 minutes at 121C (200 kPa). Steam sterilization process specifications include operating cycle, venting phase, parameters like pressure, load configuration, size/load restriction, criteria for location, and acceptance of biological or chemical indicators. Cookies used to make website functionality more relevant to you. Because of high sterilization costs, this method is an unfavorable alternative to ETO and plasma sterilization in healthcare facilities but is suitable for large-scale sterilization. The oldest and most recognized agent for inactivation of microorganisms is heat. The selection and use of disinfectants, chemical sterilants and sterilization processes in the healthcare field is dynamic, and products may become available that are not in existence when this guideline was written. ISO 11138-3, Sterilization of health care products Biological indicators Part 3: Biological indicators for moist heat sterilization processes, ISO 11140-1, Sterilization of health care products Chemical indicators Part 1: General requirements, ISO 17664, Sterilization of medical devices Information to be provided by the manufacturer for the processing of resterilizable medical devices, EN 285, Sterilization Steam sterilizers Large sterilizers, EN 868-8:1999 -Packaging materials and systems for medical devices which are to be sterilized Part 8: Re-usable sterilization containers for steam sterilizers conforming to EN 285 Requirements and test methods, PFLUG, I.J.
The various procedures used to perform moist heat sterilization process cause destruction of micro-organisms by denaturation of macromolecules. In certain cases (e.g. lessons in math, English, science, history, and more. Pasteurization is an example of moist heat sterilization below 100 C. WebSterilization is the use of a physical or chemical procedure to destroy all microbial life, including highly resistant bacterial endospores. #$NT
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Microwaves are used in medicine for disinfection of soft contact lenses, dental instruments, dentures, milk, and urinary catheters for intermittent self-catheterization925-931. Part of Springer Nature. 2. WebSterilization is the use of a physical or chemical procedure to destroy all microbial life, including highly resistant bacterial endospores. Steam sterilization is the most practiced way of sterilizationfor industrial and medical applications as it issimple,low cost and environment-friendly. One method for delivering VHP to the reaction site uses a deep vacuum to pull liquid hydrogen peroxide (30-35% concentration) from a disposable cartridge through a heated vaporizer and then, following vaporization, into the sterilization chamber. Required fields are marked *. Complete destruction ofMycobacterium boviswas obtained with 4 minutes of microwave exposure (600W, 2450 MHz)937. However, the VHP was not developed for the sterilization of medical equipment until the mid-1980s. A formaldehyde concentration of 8-16 mg/l is generated at an operating temperature of 70-75C. Decontamination & Infection Control for Health Professionals, Introduction to Astronomy: Certificate Program, DSST Environmental Science: Study Guide & Test Prep, Introduction to Natural Sciences: Certificate Program, UExcel Microbiology: Study Guide & Test Prep, Human Anatomy & Physiology: Help and Review, CSET Science Subtest II Chemistry (218): Practice & Study Guide, Gneiss Rock: Definition, Uses & Formation, What is Lava? Comparison of the characteristics of selected chemicals used as high-level disinfectants or chemical sterilants, Table 5. A gaseous ozone generator was investigated for decontamination of rooms used to house patients colonized with MRSA. Another limitation to sterilization of devices with liquid chemical germicides is the post-processing environment of the device. Denaturation is a process in which the structures of the proteins are disrupted and altered, and once the bacteria and viruses are denatured, they will be unable to cause infection. Since it is using water, the instruments or items being sterilized remain wet which increases the possibility of rusting. It is not suitable for the sterilization of oils, heat sensitive delicate materials, such as plastics, paper goods, and textiles. All Rights Reserved All ISO publications and materials are protected by copyright and are subject to the users acceptance of ISOs conditions of copyright. Sterilization by moist heat is performed by steam under pressure in pressurized vessels called autoclaves. The most common type of steam sterilizer in the microbiology laboratory is the gravity displacement type. Factors affecting the efficacy of sterilization, Table 11. - Definition, Causes & Signs, Water Potential: Definition, Equation & Measurement, Scientific Fields of Study: Areas & Definitions, Horseshoe Crabs: Habitat, Distribution & Diet, Working Scholars Bringing Tuition-Free College to the Community. Steam has high penetration power in the form of latent heat. The chamber is filled with pressurized steam at a temperature of 121 degrees Celsius/250 degrees Fahrenheit. In the former, steam is admitted at the top or the sides of the sterilizing chamber and, because the steam is lighter than air, forces air out the bottom of the chamber through the drain vent. Methods of sterilization of water we use filtration and other moist liquid material autoclave. [1] [2] Heating an article is one of the earliest forms of sterilization practiced. In addition, the design of the AOAC Sporicidal Test does not provide quantification of the microbial challenge. Minimum sterilization time should be measured from the moment when all the materials to be sterilized have reached the required temperature throughout. 1. Sterilization at a temperature of 100C. 1. In addition, the viscosity of some liquid chemical sterilants impedes their access to organisms in the narrow lumens and mated surfaces of devices922. Moist heat sterilization is one of many steps hospitals take to prevent the spread of infection. Create your account, 11 chapters | The data indicate that the survival curves for liquid chemical sterilants may not exhibit log-linear kinetics and the shape of the survivor curve may vary depending of the formulation, chemical nature and stability of the liquid chemical sterilant. Since it uses steam (water vapor), the objects will get wet and have the potential to rust. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. I have been working as a microbiologist at Patan hospital for more than 10 years. Post-sterilization, complete removal of moist heat should be ensured, and forced air removal may be needed in some cases. Air that is not removed from the chamber will interfere with steam contact. The ideal steam for sterilization is dry saturated steam and entrained water (dryness fraction 97%).813, 819Pressure serves as a means to obtain the high temperatures necessary to quickly kill microorganisms. What is the Moist Heat Sterilization Method?
document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Sterilization at temperature above 100 C. Try refreshing the page, or contact customer support. Alcohol Types, Properties & Uses | Is Alcohol a Disinfectant? WebMoist heat sterilization describes sterilization techniques that use hot water vapor as a sterilizing agent. However, it cannot sterilize heat-sensitive instruments. WebA description of the sterilization process used to sterilize the drug product in its final container-closure system, as well as a description of any other sterilization process(es) used to sterilize Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Any use, including reproduction requires our written permission. Properties of an ideal disinfectant, Table 3. It is done by two methods: Moist Heat Sterilization: It is one of the best methods of sterilization. WebISO/TS 17665-2:2009 provides general guidance on the development, validation and routine control of moist heat sterilization processes and is intended to explain the requirements set forth in ISO 17665-1. Centers for Disease Control and Prevention. Steam sterilization is the most practiced way of sterilization for industrial and medical applications as it is simple, low cost and environment-friendly. Positive spore test results are a relatively rare event838and can be attributed to operator error, inadequate steam delivery,839or equipment malfunction. This process involves exposing items to high temperatures in the presence of moisture. You will be subject to the destination website's privacy policy when you follow the link. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. Factors affecting the efficacy of sterilization, Table 11. They help us to know which pages are the most and least popular and see how visitors move around the site. WebHeating an article is one of the earliest forms of sterilization practiced.Moist heat,as the name indicates,utilizes hot air that is heavily laden with water vapour and where this moisture plays the most important role in the process of sterilization. A gaseous chlorine dioxide system for sterilization of healthcare products was developed in the late 1980s853, 952, 953. You will be subject to the destination website's privacy policy when you follow the link. The normal autoclaving temperature is 121C (250F) at 15 psi (pounds per square inch) for at least 15 minutes. Moist heat has better penetrating power than dry heat and, at a given temperature, produces a faster reduction in the number of living organisms. The forced-air or mechanical convection sterilizer is equipped with a motor-driven blower that circulates heated air throughout the chamber at a high velocity, permitting a more rapid transfer of energy from the air to the instruments920. The release of gas from paraformaldehyde tablets (placed on the lower tray) is slow and produces a low partial pressure of gas. Hydrogen Peroxide Gas Plasma | What is Gas Plasma Sterilization? Final text received or FDIS registered for formal approval, Proof sent to secretariat or FDIS ballot initiated: 8 weeks, Close of voting. After sterilization is over the strip is removed and inoculated into tryptone soy broth and incubated at56Cfor 5 days. Moist heat sterilization is a procedure in which heated, high-pressure steam is used to sterilize an object, killing any bacteria, viruses, or spores that may have contaminated the object. Chlorine dioxide is not mutagenic or carcinogenic in humans. All copyright requests should be addressed to copyright@iso.org. WebISO/TS 17665-2:2009 provides general guidance on the development, validation and routine control of moist heat sterilization processes and is intended to explain the requirements set forth in ISO 17665-1. This method is also used for the sterilization of surgical dressings and medical devices. At constant temperatures, sterilization times vary depending on the type of item (e.g., metal versus rubber, plastic, items with lumens), whether the item is wrapped or unwrapped, and the sterilizer type. Prior to sterilization the integrity of the packaging system should be made sure. The effectiveness of microwave ovens for different sterilization and disinfection purposes should be tested and demonstrated as test conditions affect the results (e.g., presence of water, microwave power). Moist heat sterilization is a procedure in which heated, high-pressure steam is used to sterilize an object. Monitoring of steam sterilization process. To receive email updates about this page, enter your email address: We take your privacy seriously. Methods of sterilization and disinfection, Table 2. Chemical indicators are affixed to the outside and incorporated into the pack to monitor the temperature or time and temperature. Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data. Methods of sterilization of water we use filtration and other moist liquid material autoclave. All rights reserved. Methods of sterilization of surgical instruments are Boiling, Incineration, Autoclave. There are two types of dry-heat sterilizers: the static-air type and the forced-air type. endstream
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The initial reports showed microwaves to be an effective microbicide. This is a preview of subscription content, access via your institution. 1. Sterilization at a temperature . Sterilization by moist heat is performed by steam under pressure in pressurized vessels called autoclaves. WebHeating an article is one of the earliest forms of sterilization practiced.Moist heat,as the name indicates,utilizes hot air that is heavily laden with water vapour and where this moisture plays the most important role in the process of sterilization. In addition,the high temperatures are not suitable for most materials919. After about 15 minutes, the objects will be sterilized. 100C. Moist heat sterilization is a procedure in which heated, high-pressure steam is used to sterilize an object. Reliable sterilization using formaldehyde is achieved when performed with a high concentration of gas, at a temperature between 60oand 80C and with a relative humidity of 75 to 100%. Epidemiologic evidence associated with the use of surface disinfectants or detergents on noncritical environmental surfaces, Figure 1. If the sterilizer fails the Bowie-Dick test, do not use the sterilizer until it is inspected by the sterilizer maintenance personnel and passes the Bowie-Dick test.813, 819, 836, Another design in steam sterilization is a steam flush-pressure pulsing process, which removes air rapidly by repeatedly alternating a steam flush and a pressure pulse above atmospheric pressure. Sterilization in saturated steam thus requires precise control of time, temperature, and pressure. Sterilization at a temperature . Ozone is produced when O2is energized and split into two monatomic (O1) molecules. The first heating destroys all bacteria in vegetative form. Entrapped air will cause a spot to appear on the test sheet, due to the inability of the steam to reach the chemical indicator. The normal autoclaving temperature is 121C (250F) at 15 psi (pounds per square inch) for at least 15 minutes. Moist heat sterilization requires low temperature and less time to complete. WebMoist heat kills microorganisms by denaturation and coagula-tion of proteins. thermolabile substances), sterilization may be carried out at temperatures below 121 C, provided that the chosen combination of time and temperature has been validated. Because a D-value can be determined at various temperatures, a subscript is used to designate the exposure temperature (i.e., D121C). The duration of the sterilization cycle is about 4 h and 15 m, and it occurs at 30-35C. Moist heat sterilization using autoclave is commonly used for the sterilization of biohazardous trash, heat, and moisture resistant materials such as aqueous preparation (culture media). Low-temperature steam formaldehyde sterilization has been found effective against vegetative bacteria, mycobacteria,B. atrophaeusandG. stearothermophilusspores andCandida albicans947-949. This method is also used for the sterilization of surgical dressings and medical devices. Sterilization by moist heat is performed by steam under pressure in pressurized vessels called autoclaves. The process involves the use of formalin, which is vaporized into a formaldehyde gas that is admitted into the sterilization chamber. Dry heat ovens are used to sterilize items that might be damaged by moist heat or that are impenetrable to moist heat (e.g., powders, petroleum products, sharp instruments).