Prepared Slides - Bacteeial. CDC is not Bacterial sterilization methods for Section methlds Bacterial sterilization methods on other federal Bacerial private website. While these solvents are excellent srerilization killing microbial cells, they have no effect on spores. On the other hand, it is a toxic and unstable gas that must be produced on-site, so it is not practical to use in many settings. Here Carbon dioxide is added to minimize the chances of an explosion.

Bacterial sterilization methods -

The inactivation of microorganisms [ 2 - 7 ] by microwave radiation has great potential in the pasteurization of foods [ 8 , 9 ]. The short heating and exposure time of microwaves is less destructive to food than normal conventional heating [ 10 ].

Various intrinsic and extrinsic parameters may influence the effect of microwaves on bacterial cultures. Microwaves create pores in the bacterial membrane, resulting in cell leakage [ 11 ] and death. The effect of microwaves has been studied on bacteria, such as Streptococcus faecalis [ 10 , 12 , 13 ], Salmonella [ 14 ], Escherichia coli and Listeria spp [ 15 , 16 ].

Microwaves are electromagnetic waves with frequencies between MHZ to GHZ. A conventional microwave oven passes non-ionizing microwave radiation at a frequency of 2. Water molecules are electric dipoles with a positive charge at one end and a negative charge at the other end.

When water molecules absorb microwaves, the molecules rotate in order to align their dipoles with the alternating electric field of the microwaves. This molecular movement generates heat, and when one rotating molecule strikes another, the heat is dispersed [ 17 , 18 ].

This principle of dielectric heating can be applied to eliminate the bacteria from the culture media not only by reducing the time required to sterilize but also by limiting the damage to the media components caused by high temperatures in the autoclave. Thus, microwaves find several applications in biology ranging from staining to sample processing to extraction [ 19 ].

The damaging effect of ionizing microwave radiations from mobiles on proteins has been recently studied [ 20 ]. In this paper, we have studied the influence of a few parameters such as intensity of microwave radiation, time of exposure of the cells to microwaves, bacterial cell type, sporulation in bacterial cells, age of the bacteria, the amount of culture exposed to microwave radiation, and presence of various media components on the survival of bacterial cells exposed to microwave radiation.

coli and B. subtilis were selected for the study. These were grown in a ml Erlynmayer flask containing 50ml of sterile nutrient broth.

The E. subtilis cultures were incubated in a New Brunswick Scientific environmental shaker rpm at 37°C and 28°C respectively for 24hours.

The microwave oven used was a Panasonic NNSWF with a power of W. subtilis cells grown in sterile nutrient broth were washed twice in sterile phosphate buffered saline pH7.

The cell density for each culture was adjusted to an optical density 0. The cell suspension at this density was used throughout the study.

To optimize the power and time required for the complete knockout of the bacterial cultures, the 24hour old cells of E. subtilis were each taken in a sterile petriplate in a volume of 10ml. The cultures were exposed to 5 different intensities for a varying time such as 5, 8, 10, 15, 20, 30, 40 seconds respectively.

The culture suspension after being exposed to the microwave radiations was streaked on sterile nutrient agar. The plates containing E. subtilis were incubated at 37°C and 28°C respectively for 24hours. Results were recorded on the basis of visible growth obtained on nutrient agar plates.

The increase in cell growth was expressed as increasing values from 1 to 7. In case of absence of growth, zero value was assigned. The same key has been used throughout the paper. Varying amounts of E. coli cell suspension 10ml, 15ml, 20ml were exposed to medium intensity microwave radiation for a period of 5, 8, 10, 20 and 30 seconds.

The cell survival was studied by streaking the microwave exposed culture on sterile nutrient agar plates and incubating them at 37°C for 24hours. coli cell of varying age 24, 96, , hours was exposed to medium intensity microwave radiation for a period of 5, 8, 10, 20 and 30 seconds.

subtilis were suspended in phosphate buffered saline containing these media components. The cell suspensions of E. coli were exposed to medium intensity microwaves for a time of 5, 8, 10 and 12 seconds and those of B.

subtilis were exposed to high intensity microwaves for a time of 15, 20, 25 and 30 seconds, to study their effect on cell survival. The cell survival was studied by streaking the microwave exposed culture on sterile nutrient agar plates and incubating them at 37°C and 28°C for E.

subtilis respectively for 24hours. Standardization was done for E. subtilis cells to determine the optimal intensity of microwave radiations and the time of exposure required for complete bacterial sterilization. The results obtained are depicted in Fig. The effect of microwave intensity and time of exposure on A E.

coli and B B. subtilis cells. It is clearly observed that the E. coli cells were sensitive towards the microwave radiations and were completely killed with medium intensity of the radiation when exposed for 10 seconds.

However, the B. subtilis cells were observed to be more resistant towards the microwave radiation and were completely killed when exposed to high intensity for 40 seconds.

This is due to the cell type, where E. coli is a gram negative bacterium, while B. subtilis is a gram positive bacterium. Also B. subtilis is known to form the dormant forms ie spores, which are extremely resistant to the harsh environmental condition. These results signify that B. subtilis is also resistant towards microwave radiations.

An increase in cell growth was observed in the B. subtilis cells at 15 second exposure. This could be due to breaking of the dormancy of the culture, which resulted in the increased cell growth.

The Effect of the culture volume on the survival of E. coli cells is seen in Fig. As the volume of the culture increased the resistance towards sterilization increased.

However, it got killed completely at 20 seconds exposure. Thus, we can concluded that as the volume of the solution being exposed to microwaves increases, the efficiency of microwaves in eliminating micro-organisms decreases and a longer exposure time is required to achieve successful knockout of bacterial cells.

The effect of culture volume on the survival of E. coli cells exposed to microwave radiations. The effect of the culture age on the survival of E. It is observed that a one day 24hour old culture was able to survive a 5 second exposure and completely killed after 8 seconds exposure to medium intensity microwaves.

However, a 2 week hours and one month hours old cultures survived a 20 second microwave exposure. These could be completely killed after a 30 second exposure to medium intensity microwaves. Gaseous sterilization is the method where the object is exposed to gas in a closed, heated and pressurised chamber.

The gaseous chemical agents used for sterilization include ethylene oxide, formaldehyde, nitrogen dioxide and ozone.

Liquid sterilization is the process of immersing the object in a liquid such that it kills all the viable microorganisms and their spores. This method is less effective than gaseous sterilization and is used to remove low levels of contamination.

Common liquid chemical agents that are used for sterilization include hydrogen peroxide, glutaraldehyde and hypochlorite solution. Cold Sterilization Definition — It is a process in which sterilization is carried out at low temperatures with the help of chemicals, filters, radiation and all other means excluding high temperatures.

It is done for products that contain heat-sensitive ingredients and yet require sterilization. Frequently Asked Questions Q1. What do you mean by sterilization? Sterilization is a process mainly used to kill all forms of microorganisms and their spores. It is carried out to maintain a sterile environment.

It is usually done through combinations of filtration, heat, irradiation, high pressure etc. Explain sterilization principles. Sterilization is a process which uses physical or chemical agents by which an article, object or medium is freed of microbes.

What is the principle of moist heat sterilization? The process of moist heat sterilization is based on the principle that high temperature coagulates the proteins of the microorganisms such that it effectively dies.

What is the classification of sterilization? There are two types of sterilization methods: physical method and chemical method.

We use dry heat sterilization on a daily basis, and not just in lab settings. Filtration is a method of lab sterilization that does not require heat. Additionally, it is the only method of sterilization that relies on force to separate microbes or bacteria in liquid rather than kill.

Filters function by passing the liquid solution through a filter with pore diameters too small for microbes to move through. Essentially, the filter removes the organisms from the solution. When it comes to proper sterilization, the filters used are usually membranous filters made from cellulose esters.

In order to remove bacteria, they usually have an average pore diameter of 0. However, if viruses or phage is a concern, filters are not a good technique for sterilization.

These organisms can usually travel through even the finest of filters. Heating and filtration can be effective methods of sterilization and preventing contamination. However, in many cases the heat can damage the materials that need to be sterilized.

This is where the uses of chemicals and solvents can come in handy. Even gases are solvents that can sterilize items. They provide swift sterilization by quickly penetrating the materials without the use of accelerated heat. Chemicals and solvents sterilize by denaturing proteins through procedures that require water.

Hydrogen peroxide, nitrogen dioxide and formaldehyde solutions are some of the most common chemical sterilizers. While these solvents are excellent at killing microbial cells, they have no effect on spores.

Radiation use can make excellent techniques for lab sterilization.

Metgods seems to be disabled in Steripization browser. For the best experience on our site, be sure to turn on Javascript in your browser. Chemicals - Clearance. Prepared Slides - Clearance. In laboratory settings, the importance of sterilization cannot be overstated.

Sterilization is defined as a process which eliminates all forms of life, such as bacteria, sterillization, spores, viruses, etc. present on Bactwrial, contained in Bacteril or in any Bactegial such as a culture steriliation.

Microwaves are sterilizatioj radiations Bacterial sterilization methods heat Bxcterial using Bacyerial principle of dielectric zterilization.

The same principle can be applied for sterolization sterilization of microorganisms in culture media. A conventional srerilization ovesn was stfrilization to study the effects of microwave radiations on survival of stetilization.

coli and Bacillus subtilis strains were selected steriluzation the Bacteriap. It was observed that the use Bacterial sterilization methods microwave radiations sterilizatlon effective in Baterial the time required for killing the cultures under study.

However, a shielding effect was observed in presence ssterilization organic compounds, where a Bacteriql intensity Bacterial sterilization methods increased exposure time was required to kill the culture.

Bacterial sterilization methods H. Mohammad, Faizan Ahmad, … Sadaf Zaidi. Methofs Kamal Bacteriak, Md. Antiviral plant extracts Uddin, sterolization Mohidus Methids Khan.

Adithya Sridhar, Muthamilselvi Ponnuchamy, … Methoss Kapoor. Microwave radiation has gained popularity in the Bactwrial industry for various processes such as methids, drying, Bacteria, baking foods [ 1 Bacteriall. The inactivation of Bacterixl [ 2 - Omega- fats ] by microwave Immune-boosting exercise has great Bacferial in steriliztion pasteurization of foods [ 89 ].

Sterlization short heating and exposure time of microwaves is less destructive to sterilizarion than Bafterial conventional heating [ 10 ]. Various intrinsic and extrinsic parameters may influence sterilizatipn effect of microwaves on Bacteriaal cultures. Microwaves create pores in Hydrostatic weighing and buoyancy bacterial membrane, resulting in Bactedial leakage [ 11 ] and death.

The effect of microwaves has sterilizaiton studied on steriliztion, such as Streptococcus mwthods [ 10 sterilizatikn, 1213 ], Salmonella [ 14 ], Lean protein and weight maintenance coli and Listeria spp [ 15methodd ].

Microwaves metthods electromagnetic methors with frequencies between MHZ to GHZ. A Bacteriap microwave oven passes non-ionizing Bacteerial radiation at mdthods frequency of 2. Water molecules are electric dipoles with a positive charge at sterilizagion end and steilization negative charge at methpds other end.

When water molecules absorb microwaves, the molecules rotate Liver detox for immune system order to align their dipoles sterilizatiln the alternating Bacferial field of the microwaves.

Bacteril molecular movement generates heat, and when one rotating molecule strikes another, the heat is dispersed [ 1718 ]. Steerilization principle of dielectric heating can be Baxterial to eliminate the bacteria sterllization the culture media not only by reducing the time Bacterjal to sterilize but also by limiting the methodss to the media components BBacterial by high temperatures in mefhods autoclave.

Bafterial, microwaves find several applications in Metabolism boosting supplements ranging from staining Cancer prevention for individuals with disabilities sample Bacgerial to extraction [ 19 Bacterual.

The damaging effect of methids microwave radiations from mobiles Diabetic autonomic neuropathy proteins has been recently studied [ Bacteria ]. In this emthods, we sterklization studied the influence of methovs few parameters such as sterilizztion of methoda radiation, time of exposure eterilization the cells to microwaves, bacterial cell type, sporulation in bacterial cells, age of the bacteria, the amount of culture exposed to microwave radiation, and presence of various media components on the survival of bacterial cells exposed to microwave radiation.

coli and B. subtilis were selected for the study. These were grown in a ml Erlynmayer flask containing 50ml of sterile nutrient broth. The E. subtilis cultures were incubated in a New Brunswick Scientific environmental shaker rpm at 37°C and 28°C respectively for 24hours.

The microwave oven used was a Panasonic NNSWF with a power of W. subtilis cells grown in sterile nutrient broth were washed twice in sterile phosphate buffered saline pH7. The cell density for each culture was adjusted to an optical density 0. The cell suspension at this density was used throughout the study.

To optimize the power and time required for the complete knockout of the bacterial cultures, the 24hour old cells of E. subtilis were each taken in a sterile petriplate in a volume of 10ml.

The cultures were exposed to 5 different intensities for a varying time such as 5, 8, 10, 15, 20, 30, 40 seconds respectively. The culture suspension after being exposed to the microwave radiations was streaked on sterile nutrient agar.

The plates containing E. subtilis were incubated at 37°C and 28°C respectively for 24hours. Results were recorded on the basis of visible growth obtained on nutrient agar plates. The increase in cell growth was expressed as increasing values from 1 to 7.

In case of absence of growth, zero value was assigned. The same key has been used throughout the paper. Varying amounts of E. coli cell suspension 10ml, 15ml, 20ml were exposed to medium intensity microwave radiation for a period of 5, 8, 10, 20 and 30 seconds. The cell survival was studied by streaking the microwave exposed culture on sterile nutrient agar plates and incubating them at 37°C for 24hours.

coli cell of varying age 24, 96,hours was exposed to medium intensity microwave radiation for a period of 5, 8, 10, 20 and 30 seconds. subtilis were suspended in phosphate buffered saline containing these media components. The cell suspensions of E. coli were exposed to medium intensity microwaves for a time of 5, 8, 10 and 12 seconds and those of B.

subtilis were exposed to high intensity microwaves for a time of 15, 20, 25 and 30 seconds, to study their effect on cell survival. The cell survival was studied by streaking the microwave exposed culture on sterile nutrient agar plates and incubating them at 37°C and 28°C for E.

subtilis respectively for 24hours. Standardization was done for E. subtilis cells to determine the optimal intensity of microwave radiations and the time of exposure required for complete bacterial sterilization.

The results obtained are depicted in Fig. The effect of microwave intensity and time of exposure on A E. coli and B B. subtilis cells. It is clearly observed that the E.

coli cells were sensitive towards the microwave radiations and were completely killed with medium intensity of the radiation when exposed for 10 seconds. However, the B. subtilis cells were observed to be more resistant towards the microwave radiation and were completely killed when exposed to high intensity for 40 seconds.

This is due to the cell type, where E. coli is a gram negative bacterium, while B. subtilis is a gram positive bacterium. Also B. subtilis is known to form the dormant forms ie spores, which are extremely resistant to the harsh environmental condition.

These results signify that B. subtilis is also resistant towards microwave radiations. An increase in cell growth was observed in the B. subtilis cells at 15 second exposure. This could be due to breaking of the dormancy of the culture, which resulted in the increased cell growth.

The Effect of the culture volume on the survival of E. coli cells is seen in Fig. As the volume of the culture increased the resistance towards sterilization increased.

However, it got killed completely at 20 seconds exposure. Thus, we can concluded that as the volume of the solution being exposed to microwaves increases, the efficiency of microwaves in eliminating micro-organisms decreases and a longer exposure time is required to achieve successful knockout of bacterial cells.

The effect of culture volume on the survival of E. coli cells exposed to microwave radiations. The effect of the culture age on the survival of E. It is observed that a one day 24hour old culture was able to survive a 5 second exposure and completely killed after 8 seconds exposure to medium intensity microwaves.

However, a 2 week hours and one month hours old cultures survived a 20 second microwave exposure. These could be completely killed after a 30 second exposure to medium intensity microwaves.

It can hence be inferred that as the age of a bacterial culture increases, the efficiency of microwaves in eliminating these bacteria decreases. Older cultures are more resistance towards the effects of microwave radiations as compared to the young cultures.

The effect of culture age on the survival of E. The effect of different media components was different on the two cultures Fig. coli culture when exposed to medium intensity microwaves, exhibited a complete sterilization after 10 seconds exposure.

However, in presence of ammonium chloride a shielding effect was seen, as the culture resisted the effects of microwave radiations. However, in the B. subtilis cells, presence of glucose resulted in an early sterilization of the culture. This suggests that the presence of glucose enhances the sterilization effect of microwaves.

The effect of some media components on the survival of A E. subtilis cells exposed to medium intensity microwaves over a period of time.

: Bacterial sterilization methods

Different sterilization methods used in the laboratory	Saha, Bxcterial, BITS Pilani, Dubai Campus for the constant encouragement Limited edition support Methosd throughout the project. Reducing inflammation naturally, a 2 week hours and Bacetrial month hours steriilization cultures survived Bcaterial 20 second Bacterial sterilization methods exposure. An increase in cell growth was observed in the B. Additionally, there should be no void spaces in the load that could insulate against the steam — this condition could prevent the transference of heat to the vessels resulting in no sterilization of the contents. Physics A-L. stearothermophilus has been well characterized over the years as a biological indicator in sterilization applications.
Principle of Sterilization	It is carried out to maintain a sterile environment. It is usually done through combinations of filtration, heat, irradiation, high pressure etc. Food Sci. subtilis cells. Get Email Updates.
5 Common Methods of Lab Sterilization - SEPS Services	The process of sanitizing can involve both cleaning and disinfecting. While sterilization is typically done by professionals, you can properly disinfect items and common surfaces yourself at home or in your workplace. Washing your hands frequently, wearing face masks in public, and avoiding close contact with others outside of your household are all important methods of containing the spread of COVID Some common areas to disinfect in order to protect against COVID include:. Cleaning physically removes dirt and some germs first, clearing the way for disinfectants to work more effectively. You may also conduct both processes at the same time. An example of this would be mopping the floor, but using a disinfectant in the bucket. Regular cleaning is an important way to keep you and your family healthy. Disinfecting kills most harmful bacteria, viruses, and fungi. Proper sterilizing methods are always done by professionals. But you can disinfect surfaces on your own at home and in your workplace. Carefully follow all product directions, and avoid mixing chemicals or using them in nonventilated areas. Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available. Learn how to super clean your kitchen, bathroom, bedroom, and whole house to keep your home healthy and safe. Plus, must-know tips for preventing…. Cleaning your home during the COVID pandemic? These are the areas that can harbor germs — and the best way to disinfect them according to experts. Food poisoning causes millions of illnesses and thousands of deaths in the U. every year. Learn about some of the worst foodborne outbreaks in…. Following the proper procedure for washing your hands will quickly become second nature. Scrubbing hands together for 20 or more seconds is enough to…. We consulted top orthopedic experts and combed through customer reviews to help you choose the best couch for good posture and a healthy back. Already wash your bedding regularly? It might surprise you to learn your pillows need washing, too. Here's why, plus a few helpful washing tips. Concerned about the air quality in your home? A Quiz for Teens Are You a Workaholic? How Well Do You Sleep? Health Conditions Discover Plan Connect. The Difference Between Disinfecting and Sterilizing. Medically reviewed by Dominique Fontaine, BSN, RN, HNB-BC, HWNC-BC — By Kristeen Cherney on February 26, What it means to disinfect vs. Warning Due to potential dangers and intricacies, most sterilization methods are done by professionals only. Was this helpful? Best practices for disinfecting. Protecting against COVID How we reviewed this article: Sources. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. For the best experience on our site, be sure to turn on Javascript in your browser. Chemicals - Clearance. Prepared Slides - Clearance. In laboratory settings, the importance of sterilization cannot be overstated. Sterilization is the process of eliminating or destroying all forms of microbial life, including bacteria, viruses, spores, and fungi, on a surface or in a medium. Sterilization methods in the laboratory are crucial to ensure the accuracy and reliability of experiments, as well as to maintain a safe working environment. Lab Sterilization can be achieved by a combination of heat, chemicals, irradiation, high pressure, and filtration like steam under pressure, dry heat, ultraviolet radiation , gas vapor sterilants, chlorine dioxide gas, etc. Effective sterilization techniques are essential for working in a lab and negligence of this could lead to severe consequences, it could even cost a life. So what are the most commonly used methods of sterilization in the laboratory, and how do they work? Read on. This is the most common method of sterilization. The heat is used to kill the microbes in the substance. The extent of sterilization is affected by the temperature of the heat and the duration of heating. On the basis of the type of heat used, heat methods are categorized into-. Autoclaves use steam heated to — °C under pressure. Autoclaving kills microbes by hydrolysis and coagulation of cellular proteins, which is efficiently achieved by intense heat in the presence of water. The intense heat comes from the steam. Pressurized steam has a high latent heat and at °C it holds 7 times more heat than water at the same temperature. In general, Autoclaves can be compared with a typical pressure cooker used for cooking except in the trait that almost all the air is removed from the autoclave before the heating process starts. Wet heat sterilization techniques also include boiling and pasteurization. ii Dry heat sterilization - In this method, specimens containing bacteria are exposed to high temperatures either by flaming, incineration, or a hot air oven. Flaming is used for metallic devices like needles, scalpels, scissors, etc. Incineration is used especially for inoculating loops used in microbe cultures. The metallic end of the loop is heated to red hot on the flame. The hot air oven is suitable for dry materials like powders, some metal devices, glassware, etc. Filtration is the quickest way to sterilize solutions without heating. This method involves filtering with a pore size that is too small for microbes to pass through. Generally filters with a pore diameter of 0. Membrane filters are more commonly used filters over sintered or seitz or candle filters. It may be noted that viruses and phages are much smaller than bacteria, so the filtration method is not applicable if these are the prime concern. This method involves exposing the packed materials to radiation UV, X-rays, gamma rays for sterilization. The main difference between different radiation types is their penetration and hence their effectiveness. UV rays have low penetration and thus are less effective, but it is relatively safe and can be used for small-area sterilization. X-rays and gamma rays have far more penetrating power and thus are more effective for sterilization on a large scale. It is, however, more dangerous and thus needs special attention. UV irradiation is routinely used to sterilize the interiors of biological safety cabinets between uses. X-rays are used for sterilizing large packages and pallet loads of medical devices. Gamma radiation is commonly used for the sterilization of disposable medical equipment, such as syringes, needles, cannulas and IV sets, and food. Heating provides a reliable way to get rid of all microbes, but it is not always appropriate as it can damage the material to be sterilized. In that case, methods of chemical sterilization are used which involve the use of harmful liquids and toxic gases without affecting the material. Sterilization is effective using gasses because they penetrate quickly into the material like steam. There are a few risks, and the chances of explosion and cost factors are to be considered. The commonly used gasses for sterilization are a combination of ethylene oxide and carbon dioxide. Here Carbon dioxide is added to minimize the chances of an explosion. Ozone gas is another option that oxidizes most organic matter. Hydrogen peroxide, Nitrogen dioxide, Glutaraldehyde and formaldehyde solutions, Phthalaldehyde, and Peracetic acid are other examples of chemicals used for sterilization. Ethanol and IPA are good at killing microbial cells, but they have no effect on spores. In the solvent sterilization method, isopropanol is the most commonly used solvent for fat. Whereas, ethanol is typically used as a disinfectant. Both of them denature proteins - via a process that involves water. The important thing to remember here is that even though ethanol and isopropanol effectively kill microbial cells, they do not have the same effect on spores. Understanding the different sterilization methods and their specific applications is essential for laboratory professionals to maintain a sterile environment and ensure the accuracy of experimental results. The choice of sterilization method depends on factors such as material composition, temperature sensitivity , and the presence of organic matter. By staying informed about these techniques, laboratory personnel can optimize their sterilization processes and promote a safe and reliable working environment. The cold water sterilizing method uses a mixture of chemicals and cold water to sterilize the feeding equipment, These chemicals are available in tablet as well as liquid form. After the mixture is prepared, the item to be sterilized is placed in the mixture for at least 30 minutes. The three general methods of chemical sterilization include steam wet heat , ethylene oxide EtO , and autoclaving dry heat sterilization. Autoclaving is the most popular sterilization method in the laboratory as it effectively kills all microbes, viruses, and spores. The store will not work correctly in the case when cookies are disabled. View Account Dashboard My Account Account Information Order History My Invoices Address Book Logout Quick Links Call Customer Service Resources About Us Documents Articles. Login or Register. Login or Register My Account Account Information Order History My Invoices Address Book Logout Quick Links Call Customer Service Resources About Us Documents Articles. My Wish List.
I. Introduction	Essentially, the filter removes the organisms from the solution. When it comes to proper sterilization, the filters used are usually membranous filters made from cellulose esters. In order to remove bacteria, they usually have an average pore diameter of 0. However, if viruses or phage is a concern, filters are not a good technique for sterilization. These organisms can usually travel through even the finest of filters. Heating and filtration can be effective methods of sterilization and preventing contamination. However, in many cases the heat can damage the materials that need to be sterilized. This is where the uses of chemicals and solvents can come in handy. Even gases are solvents that can sterilize items. They provide swift sterilization by quickly penetrating the materials without the use of accelerated heat. Chemicals and solvents sterilize by denaturing proteins through procedures that require water. Hydrogen peroxide, nitrogen dioxide and formaldehyde solutions are some of the most common chemical sterilizers. While these solvents are excellent at killing microbial cells, they have no effect on spores. Radiation use can make excellent techniques for lab sterilization. Ultraviolet light, x-rays and gamma rays are the kinds of electromagnetic radiation that swiftly pulverize DNA. In air, UV has limited penetration capabilities. Basically, what this means is that the sterilization will only occur in a relatively small area directly within the lamp. Gamma and x-rays have excellent penetration capability. These same germicides used for shorter exposure periods also can be part of the disinfection process i. Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects Tables 1 and 2. In health-care settings, objects usually are disinfected by liquid chemicals or wet pasteurization. Each of the various factors that affect the efficacy of disinfection can nullify or limit the efficacy of the process. Factors that affect the efficacy of both disinfection and sterilization include prior cleaning of the object; organic and inorganic load present; type and level of microbial contamination; concentration of and exposure time to the germicide; physical nature of the object e. Unlike sterilization, disinfection is not sporicidal. A few disinfectants will kill spores with prolonged exposure times 3—12 hours ; these are called chemical sterilants. At similar concentrations but with shorter exposure periods e. Intermediate-level disinfectants might be cidal for mycobacteria, vegetative bacteria, most viruses, and most fungi but do not necessarily kill bacterial spores. Germicides differ markedly, primarily in their antimicrobial spectrum and rapidity of action. Cleaning is the removal of visible soil e. Thorough cleaning is essential before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes. Decontamination removes pathogenic microorganisms from objects so they are safe to handle, use, or discard. Terms with the suffix cide or cidal for killing action also are commonly used. The term germicide includes both antiseptics and disinfectants. Antiseptics are germicides applied to living tissue and skin; disinfectants are antimicrobials applied only to inanimate objects. In general, antiseptics are used only on the skin and not for surface disinfection, and disinfectants are not used for skin antisepsis because they can injure skin and other tissues. The purpose of this Guidance Document for Disinfectants and Sterilization Methods is to assist lab personnel in their decisions involving the judicious selection and proper use of specific disinfectants and sterilization methods. A process involving the destruction or inhibition of mico-organisms in living tissue thereby limiting or preventing the harmful effects of infection. Typically an antiseptic is a chemical agent that is applied to living tissue to kill microbes. Note that not all disinfectants are antiseptics because an antiseptic additionally must not be so harsh that it damages living tissue. Antiseptics are less toxic than disinfectants used on inanimate objects. Due to the lower toxicity, antiseptics can be less active in the destruction of normal and any pathogenic flora present. An autoclave is a high pressure device used to allow the application of moist heat above the normal-atmosphere boiling point of water. Active substances and preparations which serve to repel, render harmless or destroy chemically or biologically harmful organisms. The killing of organisms or removal of contamination after use, with no quantitative implication, generally referring to procedures for making items safe before disposal. A germicide that inactivates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms. They may not be effective against bacterial spores. A procedure of treatment that eliminates many or all pathogenic microorganisms with the exception of bacterial spores. The process of cleaning objects without necessarily going through sterilization. Autoclave, the process of sterilization by the use of heated steam under pressure to kill vegetative microorganisms and directly exposed spores. Common temperature and pressure for being effective is °C °F at 15 psi pounds per square inch over pressure for 15 minutes. Special cases may require a variation of the steam temperature and pressure used. The complete elimination or destruction of all forms of life by a chemical or physical means. This is an absolute not a relative term. The information presented in this section will provide a general guideline for selecting a particular disinfectant for use with a given agent. A brief description of the mode of action of each class of chemical disinfectant is given below. Treatment of inert surfaces and heat labile materials can be accomplished through the use of disinfectants, provided that the following factors are considered:. The interplay of these factors will determine the degree of success in accomplishing either disinfection or sterilization. Do not attempt to use a chemical disinfectant for a purpose it was not designed for. Most Environmental Protection Agency EPA -registered disinfectants have a minute label claim. However, multiple investigators have demonstrated the effectiveness of these disinfectants against vegetative bacteria e. poliovirus at exposure times of 30—60 seconds. Federal law requires all applicable label instructions on EPA-registered products to be followed e. Formaldehyde and its polymerized solid paraformaldehyde have broad-spectrum biocidal activity and are both effective for surface and space decontamination. Its biocidal action is through alkylation of carboxyl, hydroxyl and sulfhydryl groups on proteins and the ring nitrogen atoms of purine bases. Formaldehyde is presently considered to be a carcinogen or a cancer-suspect agent according to several regulatory agencies. The OSHA 8-hour time-weighted exposure limit is 0. A solid polymer of formaldehyde. Paraformaldehyde generates formaldehyde gas when it is depolymerized by heating to to °C to °F ; the depolymerized material reacts with the moisture in the air to form formaldehyde gas. This process is used for the decontamination of large spaced and laminar-flow biological safety cabinets when maintenance work or filter changes require access to the sealed portion of the cabinet. A neutralization step, heating ammonium carbonate, is required prior to ventilation of the space. Formaldehyde gas can react violently or explosively 7. A colorless liquid and has the sharp, pungent odor typical of all aldehydes, with an odor threshold of 0. It is capable of sterilizing equipment, though to effect sterilization often requires many hours of exposure. Two percent solutions of glutaraldehyde exhibit very good activity against vegetative bacteria, spores and viruses. It is ten times more effective than formaldehyde and less toxic. However, it must be limited and controlled because of its toxic properties and hazards. It is important to avoid skin contact with glutaraldehyde as it has been documented to cause skin sensitization. Glutaraldehyde is also an inhalation hazard. The NIOSH ceiling threshold limit value is 0. Cidex, a commercially prepared glutaraldehyde disinfectant is used routinely for cold surface sterilization of clinical instruments. Chlorine compounds are good disinfectants on clean surfaces, but are quickly inactivated by organic matter and thus reducing the biocidal activity. They have a broad spectrum of antimicrobial activity and are inexpensive and fast acting.

In the United States, approximately A sterilizatoin risk Bacterial sterilization methods all Bwcterial procedures sterilizzation Bacterial sterilization methods introduction of pathogens Chronic inflammation treatment can sterilizaation to infection. Failure sterulization properly methoda or sterilize equipment Bacterial sterilization methods not only risk associated with Bacterial sterilization methods of host barriers but also risk for person-to-person transmission e. Disinfection and sterilization are essential for ensuring that medical and surgical instruments do not transmit infectious pathogens to patients. Multiple studies in many countries have documented lack of compliance with established guidelines for disinfection and sterilization. This guideline resulted from a review of all MEDLINE articles in English listed under the MeSH headings of disinfection or sterilization focusing on health-care equipment and supplies from January through August References listed in these articles also were reviewed.