Disinfection and Sterilization Sterilization and disinfection Sterilization absolute

Disinfection and Sterilization

Sterilization and disinfection Sterilization absolute absence of all viable microorgnisms, including vegetative form and endospores Disinfection a process which reduces the number of contaminating microbes, particularly those liable to cause infection Bacteriostasis to inhibit the growth of bacteria Antisepsis Asepsis

¨Disinfection is done to eliminate as many microorganisms from an item or from the environment as possible, but does not eliminate spores.

¨Disinfection is used when items cannot or needn’t be sterilized or in situations where no method of sterilization is available

Sterilization ¨Sterilization is the process by which all microorganisms, including spores, are destroyed

METHODS ¨Physical methods of disinfection and sterilization ¨Chemical methods of disinfection and sterilization

Physical methods ¨ Heat disinfection sterilization ¨ Illumination disinfection(radiation sterilization) ¨ Ionization radialization ¨ Microwave disinfection sterilization ¨ Mechanical methods

heat disinfection sterilization ¨ Applied earliest, most reliable, most extensively used ¨ Make use of the heat to destroy the microorganisms’ protein, nucleic acid, cell wall and cell membrane and cause the microorganism’ death

Heat disinfection sterilization ¨ Dry heat and moist heat dry heat----conduct the heat through the air and the conduction is slow moist heat---conduct the heat through the steam and air, and the conduction is fast, the penetration is strong

Heat disinfection sterilization ¨ Dry heat burning method(incineration) hot air drying method ¨ Moist heat boiling water disinfection steam under pressure sterilization steam of low temperature under pressure disinfection flowing steam disinfection

Dry heat ¨ ¨ Burning Hot air drying

burning method(incineration) ¨ Character Simple, fast, thorough ¨ Used for contaminated wastes, Pathologic specimens, dressings and paper with purulent secretions, patients’corpses ¨ Method directly burn or burn in incinerator

Especial points for burning method ¨ Additional use for ---oeses(接种环) used in microorganism laboratory ¨ And used when in dire need(急需) for ---some metal instrments(but sharp knives and scissors are exceptional to avoid blunting them), and kinds of china

¨ Method for metal instruments---cauterize directly on the fire for 20 seconds for china---pour alcohol of 95%~100% concentration into the china and turn the container to make the alcohol distribute evenly on the inside, then light up the alcohol until the fire becomes dead for itself

Hot air drying ¨ Make use of the specially made hot air drying oven to sterilize, the heat power spread and penetration depends on the air convection and medium conduction, and the effect of this method is reliable

¨ Suitable for the articles that do not change in character , do not damage and do not evaporate under high temperature. For example: oil, powder, glass products and metal products, etc. Not suitable for Fiber products, plastics products

¨The needed temperature and time depends on the articles character and the types of the oven

Moist heat ¨*Boiling water ¨* Steam under pressure ¨ Steam of low temperature disinfection ¨ Flowing steam disinfection

Boiling water ¨ One of the earliest used methods of disinfection ¨ Suitable for articles which are moiststable and temperature proof , e. g: metals, china, glass, and latex, etc.

method ¨ Brush and clean the articles, drip them into the water thoroughly, then heat and boil the water. ¨ Timing starts from the boiling , if anything added during the boiling, timing starts from the second boiling

Points for attention ¨ Before use of this method, the articles to be disinfected should be cleaned; the instruments with axes and the containers with covers should be opened before they are placed into water; the canals with cava should be fully filling with water before disinfection

Points for attention ¨ Too many articles being put into the water at the same time are not suitable; the basins and bowls of the same size should not be laid to overlap each other, one should ensure the every sides of the articles to contact with the water

Points for attention ¨ When to put the articles into the water and how long the disinfection process lasts depends on the kinds of the articles: Kinds of articles When to put into the water Glass products Cold water Time for disinfection(mi n) 10~15 Latex products Wrapped with 5~10 gauzes and when the water is boiling Metals and 10~15

Points for attention ¨ Mix Sodium bicarbonate into water to make the concentration 1%~2% , which can cause the boiling point to be 105°C, and can enhance the effect of killing bacteria and have the effect of antirust and removing the dirties

Points for attention ¨ The boiling point of water is influenced by the air pressure, and the higher the elevation above the sea level, the lower the air pressure and the boiling point, so the disinfection time need to be prolonged appropriately. the elevation increases each 300 m, the disinfection time prolongs 2 min accordingly

Points for attention ¨The articles should be taken out in time after being disinfected and then placed them into sterile containers

Steam under pressure ¨ The best effect among the heat disinfection sterilization and applied extensively in clinical settings ¨ Commonly used for the articles which are heat-stable, pressure-proof, and can bear damp, for example: instruments of many kinds, dressings, china, latex, glass and solutions, etc.

Steam under pressure according to different way and degree of venting the cold air, this method can be divided into two types ¨Steam under pressure venting from the underneath(下排气式 压力蒸气灭菌) ¨Forevacuum steam under pressure (预真空压力蒸气灭菌 )

Steam under pressure venting from the underneath(下排气式压力蒸气灭 菌) ¨ course: make use of the principle of Gravity displacement to let the heat steam in the autoclave down to drive the cold air out from the vents on the underneath of the autoclave until the saturated heat steam replace the cold air completely. When the saturated heat steam becomes the vapour, it will release latent heat, and it is just the latent heat that can sterilize articles. ¨ Latent heat means the heat energy which 1 g steam of 100ºc releases when it becomes 1 g water of 100ºc.

Steam under pressure venting from the underneath(下排气式压 力蒸气灭菌) ¨When pressure is 102. 97~137. 30 kpa, the temperature in the autoclave can reach 121~126ºc, 15~30 minutes is enough for sterilization

Forevacuum steam under pressure (预真空压力蒸气灭菌) ¨ Course: make use of machine to vacuumize the autoclave and make negative pressure of 2. 0~2. 7 kpa in it, then the steam can rapidly penetrate and reach the inner of the articles to sterilize. ¨ When the pressure is 205. 8 kpa, the temperature can reach 132ºc, 5~10 minutes are enough for sterilization

Points for attention ¨ The articles to be sterilized must be cleaned and dried before put into the autoclave ¨ The sizes of the packages should not be too big. Or the packages should not be too tight, the cubage of the packages is appropriate for 30 cm. X 30 cm ¨ If the containers are with bores, the bores should be opened when necessary in order to let the steam in

Points for attention ¨ The packages should be placed appropriately, there should be spaces among the packages, and the kinds of cloth should be placed onto the kinds of metal and china ¨ The cold air in the sterilizer should be let out as far as possible ¨ The articles being sterilized are not taken out for use until they are dry ¨ Monitoring the sterilization effect periodically

Steam of low temperature disinfection ¨ Steam of 73 °C ~80 °C in the vacuumized sterilizer in advance , time for 10~15 min Can kill most of pathogenic microorganisms ¨ Mainly used for articles which are not heatstable, for example: endoscope, plastics and rubber products

Flowing steam disinfection ¨ Steam of 100 °C under normal pressure, time for 15~30 min(timing starts from the steam appearing) ¨ Commonly used for the tableware, bedpans and urinals

Heat disinfection sterilization ¨Dry heat burning method(incineration) hot air drying method ¨Moist heat boiling water disinfection steam under pressure sterilization steam of low temperature under pressure disinfection flowing steam disinfection

Illumination disinfection(radiation sterilization) ¨ Make use of the ¨ Insolation under ultraviolet rays to the sun photolyze and ¨ Ultraviolet lamp denaturalize the disinfection bacteria’s protein ¨ Ozone lamp and lead the bacteria’s death

Insolation under the sun ¨The sun rays has the effects of heat, drying and ultraviolet, so they can kill bacteria in a certain degree —they can make the protein of the bacteria photolyze and denaturalize and cause the bacteria dead

Insolation under the sun ¨Commonly used for mattress, carpet, clothes, books. ¨Method: insolate the articles directly under the sun for 6 hours, and turn over the articles periodically to make each side of the articles exposure to the sun

Ultraviolet lamp disinfection ¨C wave, wavelength: 200~275 nm, the most effective: 250~270 nm ¨Ultraviolet rays can kill bacillus, virus fungus, bacterial vegetative form, spores.

Points for attention ¨ Because of its weak penetration power and low radiant energy, this method is mainly used for air and articles disinfection ¨ The proper temperature is 20°C ~40 °C, and the proper humidity is 40%~60% for the lamp to disinfect ¨ The lamp need to be changed when it has been used more than 1000 hours

Points for attention ¨ Timing starts from after the lamp is bright for 5~7 min ¨ There is 3~4 min interval between two times of lamp’ turning on ¨ After the lamp turned out , one should open the windows to ventilate ¨ The effects should be monitored periodically ¨ Keep the lamp clean, use the alcohol cotton swab to wipe lightly in order to remove the dirties and dust

Points for attention ¨ The ultraviolet rays can irritate the skin and the eyes, and the generated ozone during the irradiation is harmful to the body, so one should go out of the room being disinfected when the lamp is on, and one should wear the protection dress and the goggles.

Points for attention ¨Air disinfection: one 30 w lamp at each 10 m 2, the effective distance: within 2 m The disinfection time: 30~60 min;

Points for attention ¨Articles disinfection: lay open or hang up the articles to make their surfaces directly exposed to the ultraviolet light when disinfecting ¨The disinfection time: 20~30 min

Ozone lamp ¨ This method can be used to kill bacterial vegetative form, virus, spores, fungus and destroy botulin(肉毒杆菌 毒素) ¨ Mainly used to air disinfection, hospital dirt water disinfection and articles surfaces disinfection

Points for attention ¨ Because ozone is poisonous to human body, persons must leave when the air disinfection is ongoing, and go into the room again after another 20~30 min when the disinfection is over ¨ The temperature , the humidity, PH, and organic substances can influence ozone’s effects of disinfection

The contents required to be studied by oneself ¨Ionization radialization ¨Microwave disinfection sterilization ¨Mechanical methods

Chemical Disinfection Sterilization ¨ If heat disinfection sterilization is not suitable to use for some objects, chemical disinfectin sterilization can be considered, for example: the disinfection of skins, mucous membranes, excretions and surrounding environments optical instruments, keen metals and some plastics

Chemical Disinfection Sterilization ¨The chemicals used for disinfection are called as disinfectants. The effects of some disinfectants are enough strong to sterilize, these disinfectants are also called as sterilants.

The effects types of disinfectants Effects level Disinfectants examples High level Ethylene oxide, peracetic acid , kinds of aldehyde Kinds of alcohol, kinds of iodine, chloric disinfectants Chlorhexidine, phenolic disinfectants Normal level Low level

Chemical disinfectants use principles ¨ Select the proper disinfectants according to the types of the objects to be disinfected and the characters of the microorganisms to be killed ¨ Strictly control the effective concentration of the disinfectants and the disinfection time , the use methods ¨ The disinfectants should be changed periodically, the disinfectants which vaporize easily should be covered and examine and regulate its concentration

Chemical disinfectants use principles ¨ The objects must be cleaned and dried beforehand ¨ There should not be the gauzes, cotton and so on in the disinfectant solutions, for these kinds of objects can absorb the disinfectants so that the effect of the disinfectants can be weakened. ¨ The objects after being disinfected must be rinsed with physiological saline(生理盐水) before use to protect body tissues from the disinfectants’ irritating

use methods of chemical disinfectants ¨Immersion: Firstly, clean the articles to be disinfected, secondly, dry the articles, then, immerse the articles into the disinfectant solution. Attention to open the axes or the covers of the articles and fill the tubes fully with the disinfectant solution. Immersion time and the concentration of the solution should be according to the provision.

use methods of chemical disinfectants ¨Rubbing: Which is the method to use the chemical disinfectants to rub the surfaces of the contaminated articles or the method to disinfect the skin. e. g: using iodophor of 0. 5%~1. 0% to disinfect skin; using chloric disinfectants to rub the walls and the floors.

use methods of chemical disinfectants ¨Nebulization The method is that using a nebulizer spray the chemical disinfectants evenly on the surfaces of articles or the air. The method is commonly used for the disinfection of floors, walls, and environment, etc. Attention to wet the articles’ surfaces well when one spray.

use methods of chemical disinfectants ¨Fumigation The method means creating air to disinfect through heating a disinfectant or add oxidants into it. The method is commonly used for disinfection of space, e. g: the space of operation rooms, dressing rooms and wards. And in the closed containers this method can also be used to disinfect the contaminated articles. The formaldehyde gas and ethylene oxide gas are commonly used

The commonly use chemical disinfecants ¨ Alcohol（酒精） ¨ Iodine tincture（碘酊） ¨ Iodophor（碘伏） ¨ Hibitane(chlorhexidine)（洗必泰） ¨ Peracetic acid（过氧乙酸） ¨ Ethylene oxide（环氧乙烷） ¨ Formalin（福尔马林） ¨ Glutaraldehyde(戊二醛)