What is an Autoclave?
Autoclaves are used in sterilization. The advantage of using an autoclave is that it can reach temperatures higher than boiling water alone, so it can kill not only bacteria but also bacterial spores, which tend to be resistant. Autoclaves are used in laboratories to assure items such as glassware and surgical equipment are sterile. Have a question? Get an answer from a Medical Professional now!
Autoclaves are built around the principal that the boiling point of water increases when it is under pressure. At 15 pounds of pressure per square inch, the boiling point of water increases from 100 degrees Celsius to 121 degrees Celsius. At this temperature, all life forms are killed within 15 minutes.
Autoclaves are filled with water and work by creating steam within an enclosed environment, which builds up pressure. The air within the autoclave is gradually replaced with steam, which can reach higher temperatures than the air. High-temperature steam can surround and infiltrate the items, even reaching within the crevices in stainless steel instruments. This process kills all bacteria, viruses and bacterial spores.
Autoclaving allows materials to be sterilized within a relatively short time frame without the use of reagents. It also allows objects such as surgical and dental equipment to be reused. Therefore, autoclaving is an environmentally friendly option.
To assure the autoclave has sterilized the objects within it, it is important to note the maximum temperature and how long it was held there. There are also indicators that can be purchased and placed on the items in the autoclaves, which will change color when they have been held at the appropriate temperature for a certain length of time.
Medical equipment needs to be sterilized to prevent the spread of infection before it can be used. An autoclave is a device that sterilizes medical equipment. Autoclaves are also used by tattoo and piercing artists to sterilize needles. The autoclave developed as an extension of the research done with pasteurization processes.
History of Sterilization
Between 460 and 377 B.C. Hippocrates cleaned surgical instruments by pouring boiling water over them.
Between 1729 and 1799 Italian biologist Lazzaro Spallanzani discovered that bacteria died after being heated in sealed glass flasks for 30 minutes.
On April 20, 1862 Louis Pasteur conducted the first series of tests in which liquids where heated in pressurized containers to sterilize them. This became known as pasteurization and is still used to preserve milk, juice and other foodstuffs.
A rudimentary autoclave was first created in 1879 by French microbiologist Charles Chamberlain. He worked with the famed Louis Pasteur on his research into sterilization and pasteurization.
In its most basic form the autoclave is a pressure cooker. Water is heated in a pressurized environment to create steam. Using pressure makes it possible to heat to higher temperatures with less energy. Autoclaves are usually made of steel and have various configurations for removing air prior to pressurization. Downward displacement autoclaves use gravity to remove air. Steam pulsing autoclaves use pulses of steam along with pressurizing and depressurizing to reach optimum pressure. Vacuum pump autoclaves suck air out for pressurization. Superatmospheric autoclaves are a combination of steam pulsing and vacuum pump techniques.
How Does an Autoclave Work?
An autoclave sterilizes items by heating them with steam to a very high temperature. Some common temperatures at which autoclaves operate are: 115 degrees C/10 p.s.i., 121 degrees C/15 p.s.i., and 132 degrees C/27 p.s.i. (p.s.i.=pounds per square inch). The temperature, pressure and time of operation depend on the degree of sterilization needed.
What Does an Autoclave Kill?
An autoclave using standard settings can kill most bacteria, spores, viruses and fungi. However, most prions are not killed by an autoclave using standard settings and some organisms can survive at temperatures above 120 degrees C. Most doctor’s offices, tattoo parlors, dentist offices and other places where instruments might come in contact with contaminants have a small autoclave on site for disinfection.
Hospitals use larger autoclaves that look similar to industrial dishwashers to sterilize many items at once.
Heat kills microorganisms by causing vital proteins to coagulate. The proteins stick together causing fatal damage to the microorganism. An autoclave cooks microorganisms in the same way a pressure cooker cooks food, but at a higher temperature. Autoclaves use steam instead of dry heat because steam can more effectively transmit heat to the microorganisms.