Topic 14-Physical Agents in Sterilization

Moist heat sterilization

is one of the most effective methods of sterilization where the steam under pressure acts as a bacterial agents

160C for 1 hour

temperature and time that kills all spores

120 C-130 C for 1 and ½ hours

temperature and time which kills all vegetative bacteria

Flaming Incineration

Types of burning

Boiling, steam, fractional sterilization, pasteurization

Types of moist heat sterilization

pasteurization

extends shelf life via heat inactivation of enzymes that spoil food

Sterilization

Is any process, physical or chemical, that destroys all forms of life, is used specially to destroy microorganisms, spores, and viruses.

Fractional Sterilization

Is heating done at interval so that spores that develop into vegetative bacteria and be destroyed

Sterilization

Is the removal or destruction of all living organisms

Sterilization by moist heat Sterilization by dry heat

Physical Methods of sterilization

Gamma rays Electron accelerators

2 types of commonly used for sterilization

sterilant

A sterilizing agent is called a

Fractional Sterilization

Also known as tyndallization

every 1000ft above sea level

Boiling time should be prolonged for 5 minutes

121C (250 F) and 132 (270 F)

Common steam sterilizing temperatures

170 C for 30 minutes, 160 C for 60 minutes, and 150 C for 150 minutes

Commonly used temperatures and time that hot air ovens need to sterilize materials are

completely immersed in boiling water for proper penetration

For surgical instruments, needles, and syringes, they must be

oxidation

How are microbes killed by moist heat?

exposure to free-flowing steam at 100 deg Celsius for 30 minutes on each 3 successive days, with incubation periods between the steaming

In the years before the development of the autoclave, liquids and other objects were sterilized by

Filtration

It is capable of preventing the passage of both viable and nonviable particles and can thus be used for both the clarification and sterilization of liquids and gases

Hot Air

It uses the principle of conduction in which the heat is first absorbed by the outer surface and is then passed into the inner layer

Sterilization by Dry Heat

Laboratory equipment like Petri dishes and pipettes are challenging to sterilize by moist heat due to the penetration problem Is used when moist heat cannot be used

Scrubbing Filtration Sedimentation

Mechanical Methods Of sterilization

steam, 121-134 C

Moist heat sterilization usually involves the use of ___ at temperatures in the range of ____

coagulation of proteins

Moisture in steam causes the _____ which causes irreversible loss of function and activity of microbes

Drying Sunlight (UV rays)

Natural methods of removing microorganisms

Natural methods of removing microorganisms Ultraviolet Light/lamp Ionizing Radiation Lasers/Ultrasonics

Other Physical Means

62 degrees celsius for 30 minutes

Pasteurization Temperature:

Fractional Sterilization

This is used in materials that cannot withstand the temperature of the autoclave

Sterilization by Dry Heat

This method denatures and lyses proteins of many microorganisms

Ultraviolet Light/lamp

To prevent airborne spread of organisms especially at public places, nurseries,or operating rooms For sterilizing instruments Disadvantage: too long exposure, may damage skin

dry saturated steam and entrained water

The ideal steam for sterilization is

filtrate

The liquid which has passed through the filter is called the

sludge

The particles that settle at the bottom of a water treatment is called

Incineration

The scraps are heated till they become ash which is then disposed of later

Higher pressure

also facilitates rapid penetration of heat into deeper parts of the material

autoclaves

are machines that use pressurized steam to kill infectious agents and denature proteins

pyrogens

bacterial endotoxins from gram (-) bacteria. Which are difficult to eliminate with other techniques.

Fractional Sterilization

by repeated exposure to flowing steam at such intervals as would permit bacterial or other spores present to pass into the non resistant negative stage between exposures

oil and powder

cannot be sterilized by moist heat since moisture cannot penetrate the deeper layers of these materials

hot air oven

consists of an insulated chamber that contains a fan, thermocouples, temperature sensors, shelves and door locking controls

Sterilization

denotes the use of either physical or chemical agents to eliminate all viable microorganisms from a material or a given area

removes rather than destroys

filtration is unique because it

Pasteurization

greatly reduces the risk of food poisoning and extends shelf life by days or weeks

Free flowing steam

has the same sterilizing action as boiling

Addition of 2% solution of Na2CO3 (sodium carbonate) in boiling water

hastens the destruction of spores and prevents rusting of surgical instruments

incinerator

incineration is done in a device called an

Higher pressure

increases the boiling point of water and thus helps achieve a higher temperature for sterilization

Lasers/Ultrasonics

is a cavitation process where bubbles are agitated through high-frequency sound waves to penetrate the surface of medical instruments including holes and recesses.

autoclave

is a device that works on the principle of moist heat sterilization through generation of steam under pressure

Hot Air

is a method of dry heat sterilization which allows the sterilization of objects that cannot be sterilized by moist heat

Flaming

is a type of dry sterilization that involves exposure of metallic objects to flame for some time where the flame burns and other dust present in the instrument.

Sterilization

is the complete destruction of all microorganisms by a suitable chemical agent or by heat, either wet steam under pressure at 120 C (250 F) or more for at least 15 minutes, or dry heat at 160 to 180 C (320 to 360) for three hours

Heating

is the most common method of sterilization

Steam under pressure

is the most powerful heat sterilizing agent

pasteurization

is the process by which heat is applied to food and beverages to kill pathogens and extend shelf life Typically, the heat is below the boiling point of water (100 C or 212F)

Sterilization by Dry Heat

is the process of removing microorganisms by applying moisture free heat which is appropriate for moisture-sensitive substances Is based on the principle of conduction; that is the heat is absorbed by the outer surface of an item and then passed onward to the next layer

Filtration

is the process of separating suspended solid matter from a liquid, by causing the latter to pass through the pores of some substance, called a filter

Incineration

is the process of sterilization along with a significant reduction in the volume of the wastes. It is usually conducted during the final disposal of the hospital or other residues.

Boiling

most commonly employed, inexpensive and most practical method Temperature: 1000 deg Celsius for 30 mins Kills vegetative forms of pathogenic bacteria, fungi, and viruses

Steam

the basic principle is accomplished in an autoclave, is to expose item to direct steam contact at the required temperature and pressure for the specified time

Flaming

the instrument is dipped in alcohol or spirit before burning it in a gas flame.

Sedimentation

the process by which suspended particles settle at the bottom

Ionizing Radiation

used in spacecraft sterilization Alternative to the autoclave for sterilizing plastic petri dish and other heat sensitive materials

Scrubbing

usually done with soap and water, detergent, and etc